@article{SchaeferWeibelDonatetal.2012, author = {Sch{\"a}fer, Simon and Weibel, Stephanie and Donat, Ulrike and Zhang, Qian and Aguilar, Richard J. and Chen, Nanhai G. and Szalay, Aladar A.}, title = {Vaccinia virus-mediated intra-tumoral expression of matrix metalloproteinase 9 enhances oncolysis of PC-3 xenograft tumors}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-78220}, year = {2012}, abstract = {Background: Oncolytic viruses, including vaccinia virus (VACV), are a promising alternative to classical mono-cancer treatment methods such as surgery, chemo- or radiotherapy. However, combined therapeutic modalities may be more effective than mono-therapies. In this study, we enhanced the effectiveness of oncolytic virotherapy by matrix metalloproteinase (MMP-9)-mediated degradation of proteins of the tumoral extracellular matrix (ECM), leading to increased viral distribution within the tumors. Methods: For this study, the oncolytic vaccinia virus GLV-1h255, containing the mmp-9 gene, was constructed and used to treat PC-3 tumor-bearing mice, achieving an intra-tumoral over-expression of MMP-9. The intra-tumoral MMP-9 content was quantified by immunohistochemistry in tumor sections. Therapeutic efficacy of GLV-1h255 was evaluated by monitoring tumor growth kinetics and intra-tumoral virus titers. Microenvironmental changes mediated by the intra-tumoral MMP-9 over-expression were investigated by microscopic quantification of the collagen IV content, the blood vessel density (BVD) and the analysis of lymph node metastasis formation. Results: GLV-1h255-treatment of PC-3 tumors led to a significant over-expression of intra-tumoral MMP-9, accompanied by a marked decrease in collagen IV content in infected tumor areas, when compared to GLV-1h68-infected tumor areas. This led to considerably elevated virus titers in GLV-1h255 infected tumors, and to enhanced tumor regression. The analysis of the BVD, as well as the lumbar and renal lymph node volumes, revealed lower BVD and significantly smaller lymph nodes in both GLV-1h68- and GLV-1h255- injected mice compared to those injected with PBS, indicating that MMP-9 over-expression does not alter the metastasis-reducing effect of oncolytic VACV. Conclusions: Taken together, these results indicate that a GLV-1h255-mediated intra-tumoral over-expression of MMP-9 leads to a degradation of collagen IV, facilitating intra-tumoral viral dissemination, and resulting in accelerated tumor regression. We propose that approaches which enhance the oncolytic effect by increasing the intra-tumoral viral load, may be an effective way to improve therapeutic outcome.}, subject = {Biochemie}, language = {en} } @article{KruseShenArnoldetal.1993, author = {Kruse, N. and Shen, B. J. and Arnold, S. and Tony, H. P. and M{\"u}ller, T. and Sebald, Walter}, title = {Two distinct functional sites of human interleukin 4 are identified by variants impaired in either receptor binding or receptor activation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62451}, year = {1993}, abstract = {Interleukin 4 (IL-4) exerts a decisive role in the coord.ination of proteelive immune responses against parasites, particularly helminths. A disregulation of ll.r4 function is possibly involved in the genesis of allergic disease states. The search for important amino acid residues in human ll.r4 by mutational analysis of charged invariant amino acid positions identified two distinct functional sites in the 4-helix-bundle protein. Site 1 was marked by amino acid substitutions of the glutamic acid at position 9 in helix A and arginine at position 88 in helix C. Exchanges at both positions led to IL-4 variants deficient in binding to the extracellular domain of the ll.r4 receptor (IL-4ReJ. In parallel, up to 1000-fold increased concentrations of this type of variant were required to induce T -cell proliferation and B-eeil CD23 expression. Site 2 was marked by amino acid exchanges in helix D at positions 121, 124 and 125 (arginine, tyrosine and serine respectively in the wild-type).ß.A variants affected at site 2 exhibited partial agonist activity during T -cell proliferation; however, they still bound with high affinity to IL-4Rex. [The generation of an IL-4 antagonist by replacing tyrosine 124 with aspartic acid has been described before by Kruse et al. (1992) (EMBO }., 11, 3237-3244)]. These findings indicate that IL-4 functions by bind.ing IL-4Rex via site 1 which is constituted by residues on helices A and C. They further suggest that the association of a second, still undetined receptor protein with site 2 in helix D activates the receptor system and generates a transmembrane signal.}, subject = {Biochemie}, language = {en} } @article{McCarthySchairerSebald1985, author = {McCarthy, J. E. and Schairer, H. U. and Sebald, Walter}, title = {Translational initiation frequency of atp genes from Escherichia coli: identification of an intercistronic sequence that enhances translation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62657}, year = {1985}, abstract = {The c, b and {\"o} subunit genes of the Escherichia coli atp operon were cloned individually in an expression vector between the tac fusion promoter and the galK gene. The relative rates of subunit synthesis directed by the cloned genes were similar in vitro andin vivo and compared favourably with the subunit stoichiometry of the assembled proton-translocating A TP synthase of E. coli in vivo. The rate of synthesis of subunit c was at least six times that of subunit b and 18 times that of subunit {\"o}. Progressive shortening of the long intercistronic sequence lying upstream of the subunit c gene showed that maximal expression of this gene is dependent upon the presence of a sequence stretching > 20 bp upstream of the Shine-Dalgarno site. This sequence thus acts to enhance the rate of translational initiation. The possibility that similar sequences might perform the same function in other operons of E. coli and bacteriophage A is also discussed. Translation of the subunit b cistron is partially coupled to translation of the preceding subunit c cistron. In conclusion, the expression of all the atp operon genes could be adjusted to accommodate the subunit requirements of A TP synthase assembly primarily by means of mechanisms which control the efficiency of translational initiation and re-initiation at the respective cistron start codons.}, subject = {Biochemie}, language = {en} } @article{HoppeSebald1986, author = {Hoppe, J. and Sebald, Walter}, title = {Topological studies suggest that the pathway of the protons through F\(_0\) is provided by amino acid residues accessible from the lipid phase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62602}, year = {1986}, abstract = {The structure of the F0 part of ATP synthases from E. coli and Neurospora crassa was analyzed by hydrophobic surface labeling with [125I]TID. In the E. co/i F0 all three subunits were freely accessible to the reagent, suggesting that these subunits are independently integrated in the membrane. Labeted amino acid residues were identified by Edman degradation of the dicyclohexylcarbodiimide binding (DCCD) proteins from E. coli and Neurospora crassa. The very similar patterns obtained with the two homologaus proteins suggested the existence of tightly packed cx-helices. The oligomeric structure of the DCCD binding protein appeared to be very rigid since little, if any, change in the labeling patternwas observed upon addition of oligomycin or DCCD to membranes from Neurospora crassa. When membrancs were pretrcated with DCCD prior to the reaction with [125I]TID an additionally labeled amino acid appeared at the position of Glu·65 which binds DCCD covalently, indicating the Jocation of this inhibitor on the outside of the oligomer. It is suggested that proton conduction occurs at the surface of the oligomer of the DCCD binding protein. Possibly this oligomer rotates against the subunit a or b and thus enables proton translocation. Conserved residues in subunit a, probably located in the Iipid bilayer, might participate in the pro· ton translocation mechanism.}, subject = {Biochemie}, language = {en} } @article{SchairerHoppeSebaldetal.1982, author = {Schairer, H. U. and Hoppe, J. and Sebald, Walter and Friedl, P.}, title = {Topological and functional aspects of the proton conductor, F\(_0\), of the Escherichia coli ATP-synthase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62721}, year = {1982}, abstract = {The isolated H\(^+\) conductor, F\(_0\) , of the Escherichia co1i ATP-synthase consists of three subunits, a, b, and c. H\(^+\) -permeable liposomes can be reconstit~ted with F\(_0\) and lipids; addition of F\(_1\)-ATPase reconstitutes a functional ATP-synthase. Mutants with altered or misslng F\(_0\) subunits are defective in H\(^+\) conduction. Thus, all three subunits are necessary for the expression of H\(^+\) conduction. The subunits a and b contain binding sites for F\(_1\)• Computer calculations, cross-links, membrane-permeating photo-reactive labels, and proteases were used to develop tentative structural models for the individual F\(_0\) subunits.}, subject = {Biochemie}, language = {en} } @article{FlueggeFischerGrossetal.1989, author = {Fl{\"u}gge, U. I. and Fischer, K. and Gross, A. and Sebald, Walter and Lottspeich, F. and Eckerskorn, C.}, title = {The triose phosphate-3-phosphoglycerate-phosphate translocator from spinach chloroplasts: nucleotide sequence of a full-length cDNA clone and import of the in vitro synthesized precursor protein into chloroplasts}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62559}, year = {1989}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{HoppeFriedlSchaireretal.1983, author = {Hoppe, J. and Friedl, P. and Schairer, H. U. and Sebald, Walter and Meyenburg, K. von and Jorgensen, B. B.}, title = {The topology of the proton translocating F\(_0\) component of the ATP synthase from E. coli K12: studies with proteases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62718}, year = {1983}, abstract = {The accessibility of the three F\(_0\) subunits a, b and c from the Escherichia coli Kll A TP synthase to various proteases was studied in F\(_1\)-depleted inverted membrane vesicles. Subunit b was very sensitive to all applied proteases. Chymotrypsin produced a defined fragment of mol. wt. 1S 000 which remained tightly bound to the membrane. The cleavage site was located at the C-terminal region of subunit b. Larger amounts of proteases were necessary to attack subunit a (mol. wt. 30 000). There was no detectable deavage of subunit c. It is suggested that the major hydrophilic part of subunit b extends from the membrane into the cytoplasm and is in contact with the F\(_1\) sector. The F\(_1\) sector was found to afford some protection against proteolysis oftheb subunit in vitro andin vivo. Protease digestion bad no influence on the electro-impelled H\(^+\) conduction via F\(_0\) bot ATP-dependent H\(^+\) translocation could not be reconstituted upon binding of F\(_1\)• A possible role for subunit b as a linker between catalytic events on the F\(_1\) component and the proton pathway across the membrane is discussed.}, subject = {Biochemie}, language = {en} } @phdthesis{Fischer2010, author = {Fischer, Andreas}, title = {The Role of Protein-Protein Interactions in the Activation Cycle of RAF Kinases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48139}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Members of the RAF protein kinase family are key regulators of diverse cellular processes. The need for isoform-specific regulation is reflected by the fact that all RAFs not only display a different degree of activity but also perform isoform-specific functions at diverse cellular compartments. Protein-protein-interactions and phosphorylation events are essential for the signal propagation along the Ras-RAF-MEK-ERK cascade. More than 40 interaction partners of RAF kinases have been described so far. Two of the most important regulators of RAF activity, namely Ras and 14-3-3 proteins, are subject of this work. So far, coupling of RAF with its upstream modulator protein Ras has only been investigated using truncated versions of RAF and regardless of the lipidation status of Ras. We quantitatively analyzed the binding properties of full-length B- and C-RAF to farnesylated H-Ras in presence and absence of membrane lipids. While the isolated Ras-binding domain of RAF exhibit a high binding affinity to both, farnesylated and nonfarnesylated H-Ras, the full-length RAF kinases demonstrate crucial differences in their affinity to Ras. In contrast to C-RAF that requires carboxyterminal farnesylated H-Ras for interaction at the plasma membrane, B-RAF also binds to nonfarnesylated H-Ras in the cytosol. For identification of the potential farnesyl binding site we used several fragments of the regulatory domain of C-RAF and found that the binding of farnesylated H-Ras is considerably increased in the presence of the cysteine-rich domain of RAF. In B-RAF a sequence of 98 amino acids at the extreme N terminus enables binding of Ras independent of its farnesylation status. The deletion of this region altered Ras binding as well as kinase properties of B-RAF to resemble C-RAF. Immunofluorescence studies in mammalian cells revealed essential differences between B- and C-RAF regarding the colocalization with Ras. In conclusion, our data suggest that that B-RAF, in contrast to C-RAF, is also accessible for nonfarnesylated Ras in the cytosolic environment due to its prolonged N terminus. Therefore, the activation of B-RAF may take place both at the plasma membrane and in the cytosolic environment. Furthermore, the interaction of RAF isoforms with Ras at different subcellular sites may also be governed by the complex formation with 14-3-3 proteins. 14-3-3 adapter proteins play a crucial role in the activation of RAF kinases, but so far no information about the selectivity of the seven mammalian isoforms concerning RAF association and activation is available. We analyzed the composition of in vivo RAF/14-3-3 complexes isolated from mammalian cells with mass spectrometry and found that B-RAF associates with a greater variety of 14-3-3 proteins than C- and A-RAF. In vitro binding assays with purified proteins supported this observation since B-RAF showed highest affinity to all seven 14-3-3 isoforms, whereas C-RAF exhibited reduced affinity to some and A-RAF did not bind to the 14-3-3 isoforms epsilon, sigma, and tau. To further examine this isoform specificity we addressed the question of whether both homo- and heterodimeric forms of 14-3-3 proteins participate in RAF signaling. By deleting one of the two 14-3-3 isoforms in Saccharomyces cerevisiae we were able to show that homodimeric 14-3-3 proteins are sufficient for functional activation of B- and C-RAF. In this context, the diverging effect of the internal, inhibiting and the activating C-terminal 14-3-3 binding domain in RAF could be demonstrated. Furthermore, we unveil that prohibitin stimulates C-RAF activity by interfering with 14-3-3 at the internal binding site. This region of C-RAF is also target of phosphorylation as part of a negative feedback loop. Using tandem MS we were able to identify so far unknown phosphorylation sites at serines 296 and 301. Phosphorylation of these sites in vivo, mediated by activated ERK, leads to inhibition of C-RAF kinase activity. The relationship of prohibitin interference with 14-3-3 binding and phosphorylation of adjacent sites has to be further elucidated. Taken together, our results provide important new information on the isoform-specific regulation of RAF kinases by differential interaction with Ras and 14-3-3 proteins and shed more light on the complex mechanism of RAF kinase activation.}, subject = {Signaltransduktion}, language = {en} } @article{HoppeSchairerSebald1980, author = {Hoppe, J. and Schairer, H. U. and Sebald, Walter}, title = {The proteolipid of a mutant ATPase from Escherichia coli defective in H\(^+\)-conduction contains a glycine instead of the carbodiimide-reactive aspartyl residue}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62769}, year = {1980}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{HarnischWeissSebald1985, author = {Harnisch, U. and Weiss, H. and Sebald, Walter}, title = {The primary structure of the iron-sulfur subunit of ubiquinol-cytochrome c reductase from Neurospora, determined by cDNA and gene sequencing}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62631}, year = {1985}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{RoemischTropschugSebaldetal.1987, author = {R{\"o}misch, J. and Tropschug, M. and Sebald, Walter and Weiss, H.}, title = {The primary structure of cytochrome c\(_1\) from Neurospora crassa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62578}, year = {1987}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{GesslerGrupeGrzeschiketal.1992, author = {Gessler, Manfred and Grupe, Andrew and Grzeschik, Karl-Heinz and Pongs, Olaf}, title = {The potassium channel gene HK1 maps to human chromosome 11p14.1, close to the FSHB gene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59184}, year = {1992}, abstract = {Transiently activating (A-type) potassium (K) channels are important regulators of action potential and action potential firing frequencies. HK1 designates the firsthuman cDNA that is highly homologous to the rat RCK4 cDNA that codes for an A-type K-channel. The HK1 channel is expressed in heart. By somatic cell hybrid analysis, the HK1 gene has been assigned to human chromosome 11p13-pl4, the WAGR deletion region (Wilms tumor, aniridia, genito-urinary abnormalities and mental retardation). Subsequent pulsed field gel (PFG) analysis and comparison with the well-established PFG map of this region localized the gene to 11p14, 200-600 kb telomeric to the FSHB gene.}, subject = {Biochemie}, language = {en} } @article{ViebrockPerzSebald1982, author = {Viebrock, A. and Perz, A. and Sebald, Walter}, title = {The imported preprotein of the proteolipid subunit of the mitochondrial ATP synthase from Neurospora crassa. Molecular cloning and sequencing of the mRNA}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62742}, year = {1982}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{WeichSebaldSchaireretal.1986, author = {Weich, H. A. and Sebald, Walter and Schairer, H. U. and Hoppe, J.}, title = {The human osteosarcoma cell line U-2 OS expresses a 3.8 kilobase mRNA which codes for the sequence of the PDGF-B chain}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62588}, year = {1986}, abstract = {A cDNA clone of about 2500 basepairswas prepared from the human osteosarcoma cellline U-2 OS by hybridizing with a v-sis probe. Sequence analysis showed that this cDNA contains the coding region for the PDGF-B chain. Here we report that the mitogen secreted by these osteosarcoma cells contains the PDGF-B chain and is probably a homodimer of two B-chains.}, subject = {Biochemie}, language = {en} } @article{GesslerHameisterHenryetal.1990, author = {Gessler, Manfred and Hameister, H. and Henry, I. and Junien, C. and Braun, T. and Arnold, H. H.}, title = {The human MyoD1 (MYF3) gene maps on the short arm of chromosome 11 but is not associated with the WAGR locus or the region for the Beckwith-Wiedemann syndrome}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59221}, year = {1990}, abstract = {The human gene encoding the myogenic determination factor myf3 (mouse MyoD1) has been mapped to the short arm of chromosome 11. Analysis of several somatic cell hybrids containing various derivatives with deletions or translocations revealed that the human MyoD (MYF3) gene is not associated with the WAGR locus at chromosomal band 11pl3 nor with the loss of the heterozygosity region at 11p15.5 related to the Beckwith-Wiedemann syndrome. Subregional mapping by in situ hybridization with an myf3 specific probe shows that the gene resides at the chromosomal band llp14, possibly at llp14.3.}, subject = {Biochemie}, language = {en} } @article{GesslerKoenigBruns1992, author = {Gessler, Manfred and K{\"o}nig, A. and Bruns, G. A. P.}, title = {The genomic organization and expression of the WT1 gene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59195}, year = {1992}, abstract = {The Wilms tumor gene WTl, a proposed tumor suppressor gene, has been identifled based on its location within a homozygous deletion found in tumor tissue. The gene encodes a putative transcription factor containing a Cys/His zinc finger domain. The critical homozygous deletions, however, are rarely seen, suggesting that in many cases the gene may be inactivated by more subtle alterations. To facilitate the seareh for smaller deletions and point mutations we have established the genomic organization of the WTl gene and have determined the sequence of all 10 exons and flanking intron DNA. The pattern of alternative splicing in two regions has been characterized in detail. These results will form the basis for future studies of mutant alleles at this locus.}, subject = {Biochemie}, language = {en} } @article{SebaldGrafLukins1979, author = {Sebald, Walter and Graf, T. and Lukins, H. B.}, title = {The dicyclohexylcarbodiimide-binding protein of the mitochondrial ATPase complex from Neurospora crassa and Saccharomyces cerevisiae. Identification and isolation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62792}, year = {1979}, abstract = {Incubation of mitochondria from Neuraspara crassa and Saccharomyces cerevisiae with the radioactive ATPase inhibitor [14C]dicyclohexylcarbodiimide results in the irreversible and rather specific labelling of a low-molecular-weight polypeptide. This dicyclohexylcarbodiimide-binding protein is identical with the smallest subunit (Mr 8000) of the mitochondrial ATPase complex, and it occurs as oligomer, probably as hexamer, in the enzyme protein. The dicyclohexylcarbodiimide-binding protein is extracted from whole mitochondria with neutral chloroformjmethanol both in the free and in the inhibitor-modified form. In Neuraspara and yeast, this extraction is highly selective and the protein is obtained in homogeneaus form when the mitochondria have been prewashed with certain organic solvents. The bound dicyclohexylcarbodiimide Iabel is enriched in the purified protein up to 50-fold compared to whole mitochondria. Based on the amino acid analysis, the dicyclohexylcarbodiimide-binding protein from Neurospora and yeast consists of at least 81 and 76 residues, respectively. The content of hydrophobic residues is extremely high. Histidine and tryptophan are absent. The N-terminal ~mino acid is tyrosine in Neuraspara and formylmethionine in yeast.}, subject = {Biochemie}, language = {en} } @article{GrafSebald1978, author = {Graf, T. and Sebald, Walter}, title = {The dicyclohexylcarbodiimide-binding protein of the mitochondrial ATPase complex from beef heart. Isolation and amino acid composition}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62806}, year = {1978}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{MichelWachterSebald1979, author = {Michel, R. and Wachter, E. and Sebald, Walter}, title = {Synthesis of a larger precursor for the proteolipid subunit of the mitochondrial ATPase complex of Neurospora crassa in a cell-free wheat germ system}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62789}, year = {1979}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{SebaldFriedlSchaireretal.1982, author = {Sebald, Walter and Friedl, P. and Schairer, H. U. and Hoppe, J.}, title = {Structure and genetics of the H\(^+\)-conducting F\(_0\) portion of the ATP synthase}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62733}, year = {1982}, abstract = {The ATP synthase occurs in remarkably conserved form in procaryotic and eucaryotic cells. Thus, our present knowledge of ATP synthase is derived from sturlies of the enzyme from different organisms, each affering specific experimental possibilities. In recent tim es, research on the H\(^+\) -conducting F0 part of the ATP synthase has been greatly stimulated by two developments in the Escherichio coli system. Firstly, the purification and reconstitution of the whole ATP synthase as weil as the proton conductor Fa from E. coli have been achieved. These functionally active preparations are well defined in terms of subunit composition, similar to the thermophilic enzyme from PS-3 studied by Kagawa's group.u Secondly, the genetics and the molecular cloning of the genes of all the F\(_0\) subunits from E. coli yielded information on the function of subunit polypeptides and essential amino acid residues. Furthermore, the amino acid sequence of hydrophobic F\(_0\) subunits, which are difficult to analyze by protein-chemical techniques, could be derived from the nucleotide sequence of the genes. These achievements, which shall be briefly summarized in the next part of this communication, provide the framework to study specific aspects of the structure and function of the F\(_0\) subunits.}, subject = {Biochemie}, language = {en} } @phdthesis{Delto2015, author = {Delto, Carolyn Francesca}, title = {Structural and Biochemical Characterization of the GABA(A) Receptor Interacting Protein Muskelin}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115922}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2015}, abstract = {In a study from 2011, the protein muskelin was described as a central coordinator of the retrograde transport of GABA(A) receptors in neurons. As muskelin governs the transport along actin filaments as well as microtubules, it might be the first representative of a novel class of regulators, which coordinate cargo transport across the borders of these two independent systems of transport paths and their associated motorproteins. To establish a basis for understanding the mode of operation of muskelin, the aim of this thesis was an in-depth biochemical and structural characterization of muskelin and its interaction with the GABA(A) receptor. One focus of the work was the analysis of the oligomerization of muskelin. As could be demonstrated, the oligomerization is based on two independent interactions mediated by different domains of the protein: a known interaction of the N-terminal discoidin domain with the C-terminal portion, termed head-to-tail interaction, and a dimerization of the LisH motif in muskelin that was so far neglected in the literature. For the detailed studies of both binding events, the solution of a crystal structure of a fragment of muskelin, comprising the Discoidin domain and the LisH motif, was an important basis. The fragment crystallized as a dimer, with dimerization being mediated solely by the LisH motif. Biochemical analysis corroborated that the LisH motif in muskelin serves as a dimerization element, and, moreover, showed that the C-terminal domain of the protein substantially stabilizes this dimerization. In addition, the crystal structure revealed the molecular composition of the surface of the head in the head-to-tail interaction, namely the discoidin domain. This information enabled to map the amino acids contributing to binding, which showed that the binding site of the head-to-tail interaction coincides with the generic ligand binding site of the discoidin domain. As part of the analyses, residues that are critical for LisH-dimerization and the head-to-tail binding, respectively, were identified, whose mutation specifically interfered with each of the interactions separately. These mutations allowed to investigate the interplay of these interactions during oligomerization. It could be shown that recombinant muskelin assembles into a tetramer to which both interactions, the LisH-dimerization and the head-to-tail binding, contribute independently. When one of the two interactions was disturbed, only a dimer mediated via the respective other interaction could be formed; when both interactions were disturbed, the protein was present as monomer. Furthermore, Frank Heisler in the group of Matthias Kneussel was able to show the drastic impact of an impaired LisH-dimerization on muskelin in cells using these mutations. Disturbing the LisH-dimerization led to a complete redistribution of the originally cytoplasmic muskelin to the nucleus which was accompanied by a severe impairment of its function during GABA(A) receptor transport. Following up on these results in an analysis of muskelin variants, for which alterations of the subcellular localization had been published earlier, the crucial influence of LisH-dimerization to the subcellular localization and thereby the role of muskelin in the cell was confirmed. The biochemical studies of the interaction of muskelin and the alpha1 subunit of the GABA(A) receptor demonstrated a direct binding with an affinity in the low micromolar range, which is mediated primarily by the kelch repeat domain in muskelin. For the binding site on the GABA(A) receptor, it was confirmed that the thirteen most C-terminal residues of the intracellular domain are critical for the binding of muskelin. In accordance with the strong conservation of these residues among the alpha subunits of the GABA(A) receptor, it could be shown that an interaction with muskelin in vitro is also possible for the alpha2 and alpha5 subunits. Based on the comparison of the binding sites between the homologous subunits, tentative conclusions can be drawn about the details of the binding, which may serve as a starting point for follow-up studies. This thesis thereby makes valuable contributions to the understanding of muskelin, in particular the significance of its oligomerization. It furthermore provides an experimental framework for future studies that address related topics, such as the characterization of other muskelin interaction partners, or the questions raised in this work.}, subject = {Oligomerisation}, language = {en} } @article{DummerPosseckertNestleetal.1992, author = {Dummer, R. and Posseckert, G. and Nestle, F. and Witzgall, R. and Burger, M. and Becker, J. C. and Sch{\"a}fer, E. and Wiede, J. and Sebald, Walter and Burg, G.}, title = {Soluble interleukin-2 receptors inhibit interleukin 2-dependent proliferation and cytotoxicity: explanation for diminished natural killer cell activity in cutaneous T-cell lymphomas in vivo?}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62473}, year = {1992}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{KruseLehrnbecherSebald1991, author = {Kruse, N. and Lehrnbecher, T. and Sebald, Walter}, title = {Site-directed mutagenesis reveals the importance of disulfide bridges and aromatic residues for structure and proliferative activity of human interleukin-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62505}, year = {1991}, abstract = {Mutant proteins (muteins) of human lnterleukin-4 (llA) were constructed by means of in vitro mutagenesis. The muteins were expressed in E. co/1, submitted to a renaturation and purification protocol and analysed for biological activity. Exchange of the cysteines at either position 46 or 99 which form one of the three disulfide bridges resulted. in a nearly co•mplete loss · of biological actiyity and an unstable protein. The exchange of tyrosine 124 also inactivated the protein, while a mutation of tyrosine 56 left some residual activity. Exchange of the other four cysteines or of · the single tryptophane had smaller etTects.}, subject = {Biochemie}, language = {en} } @phdthesis{Zanucco2011, author = {Zanucco, Emanuele}, title = {Role of oncogenic and wild type B-RAF in mouse lung tumor models}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69603}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Von Wachstumsfaktoren regulierte Signalkaskaden sind Schl{\"u}sselelemente in der Gewebeentwicklung und Geweberegeneration. Eine Deregulation dieser Kaskaden f{\"u}hrt zu Entwicklungsst{\"o}rungen und neoplastischen Krankheiten. F{\"u}r viele humane Krebsformen sind aktivierende Mutationen der Kinasen der RAF Familie verantwortlich. Das erste Projekt dieser Doktorarbeit fokussiert auf der Rolle des B-RAF V600E, welches als eine der am h{\"a}ufigsten vorkommenden Mutantionen in humanen Krebszellen identifiziert worden ist. Um die onkogene Funktion des B-RAF V600E zu untersuchen, haben wir transgene Mauslinien hergestellt, welche das aktivierte Onkogen spezifisch in alveolaren Lungenepithelzellen des Typ II exprimieren. Konstitutive Expression des B-RAF V600E f{\"u}hrte zu einer abnormen alveolaren Epithelzellbildung und zu Emphysem-{\"a}hnlichen L{\"a}sionen. Diese L{\"a}sionen wiesen Zeichen einer Gewebsumstrukturierung auf, oft in Assoziation mit chronischer Inflammation und geringer Inzidenz von Lungentumoren. Die Infiltration der entz{\"u}ndlichen Zellen erfolgte erst nach der Entstehung von Emphysem-{\"a}hnlichen L{\"a}sionen und k{\"o}nnte zur sp{\"a}teren Tumorbildung beigetragen haben. Diese Ergebnisse unterst{\"u}tzen ein Modell, in welchem der kontinuierliche regenerative Prozess eine tumorf{\"o}rdernde Umgebung schafft. Dabei induziert die Aktivit{\"a}t des onkogenen B-RAF eine alveolare St{\"o}rung, welche urs{\"a}chlich verantwortlich ist f{\"u}r den kontinuierlichen regenerativen Prozess. Das zweite Projekt fokussiert auf die Rolle von endogenem (wildtypischen) B-RAF in einem durch onkogenes C-RAF induzierten Maus Lungentumormodell. F{\"u}r unsere Untersuchungen haben wir eine Mauslinie geschaffen, in welcher B-RAF in den C-RAF Lungentumoren konditionell eliminiert werden kann. Eine konditionelle Eliminierung des B-RAF hat die Entstehung von Lungentumoren nicht blockiert, aber zu reduziertem Tumorwachstum gef{\"u}hrt. Dieses reduzierte Tumorwachstum konnte auf eine reduzierte Zellproliferation zur{\"u}ckgef{\"u}hrt werden. Außerdem konnten wir durch die B-RAF Elimination eine Reduktion der Intensit{\"a}t der mitogenen Signalkaskade beobachten. Insgesamt deuten die Ergebnisse darauf hin, dass das onkogene Potential von C-RAF in vivo unabh{\"a}ngig von B-RAF ist und eine Kooperation von B-RAF und C-RAF jedoch f{\"u}r die vollst{\"a}ndige Aktivierung der mitogenen Signalkaskade wichtig ist.}, subject = {Lungenkrebs}, language = {en} } @article{vanHeyningenBickmoreSeawrightetal.1990, author = {van Heyningen, V. and Bickmore, W. A. and Seawright, A. and Fletcher, J. M. and Maule, J. and Fekete, G. and Gessler, Manfred and Bruns, G. A. and Huerre-Jeanpierre, C. and Junien, C.}, title = {Role for the Wilms tumor gene in genital development?}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59238}, year = {1990}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{TonyLehrnbecherMerzetal.1991, author = {Tony, H. P. and Lehrnbecher, T. and Merz, H. and Sebald, Werner and Wilhelm, M.}, title = {Regulation of IL-4 responsiveness in lymphoma B cells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62520}, year = {1991}, abstract = {The responsiveness to IL-4 with and without costimulation with anti-IgM antibodies or phorbolester was studied in 35 cases of low grade non-Hodgkin Iymphoma by analyzing enhancement of CD23 and HLA dass li expression. The predominant phenotype responds directly to IL-4. Separate differentiation states can be distinguished according to coordinate or differential upregulation of CD23 and HLA dass II molecules by IL-4 alone, and differences in responsiveness to anti-IgM antibodies. A particular subgroup of B-lymphoma cells defines a separate stage of B-eeil differentiation. They fail to express high affinity binding sites for IL-4 and accordingly do not respond to IL-4- mediated signals. Cross-linking membrane lgM receptors or direct activation of protein kinase C via phorbolester induces IL-4 receptor expression and subsequent IL-4 reactivity.}, subject = {Biochemie}, language = {en} } @article{DemchukMuellerOschkinatetal.1994, author = {Demchuk, E. and Mueller, T. and Oschkinat, H. and Sebald, Walter and Wade, R. C.}, title = {Receptor binding properties of four-helix-bundle growth factors deduced from electrostatic analysis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62424}, year = {1994}, abstract = {Hormones of the hematopoietin class mediate signal transduction by binding to specific transmembrane receptors. Structural data show that the human growth hormone (hGH) forms a complex with a homodimeric receptor and that hGH is a member of a class of hematopoietins possessing an antiparallel 4-a-helix bundle fold. Mutagenesis experiments suggest that electrostatic interactions may have an important influence on hormonereceptor recognition. In order to examine the specificity of hormone-receptor complexation, an analysis was made of the electrostatic potentials of hGH, interleukin-2 (IL-2), interleukin-4 (IL-4), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and the hGH and IL-4 receptors. The binding surfaces of hGH and its receptor, and of IL-4 and its receptor, show complementary electrostatic potentials. The potentials of the hGH and its receptor display approximately 2-fold rotational symmetry because the receptor subunits are identical. In contrast, the potentials of GM-CSF and IL-2 Iack such symmetry, consistent with their known high affinity for hetero-oligomeric receptors. Analysis of the electrostatic potentials supports a recently proposed hetero-oligomeric model for a high-affinity IL-4 receptor and suggests a possible new receptor binding mode for G-CSF; it also provides valuable information for guiding structural and mutagenesis studies of signal-transducing proteins and their receptors.}, subject = {Biochemie}, language = {en} } @article{NeupertSebaldSchwabetal.1969, author = {Neupert, W. and Sebald, Walter and Schwab, A. J. and Pfaller, A. and B{\"u}cher, T.}, title = {Puromycin sensitivity of ribosomal label after incorporation of \(^{14}\)C-labelled amino acids into isolated mitochondria from Neurospora crassa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62899}, year = {1969}, abstract = {Radioactive amino acids were incorporated into isolated mitochondria from Neurospora crassa. Then the mitochondrial ribosomes were isolated and submitted to density gradient centrifugation. A preferential labelling of polysomes was observed. However, when the mitochondrial suspension was treated with puromycin after amino acid incorporation, no radioactivity could be detected in either the monosomes or the polysomes. The conclusion is drawn that isolated mitochondria under these conditions do not incorporate significant amounts of amino acids into proteins of their ribosomes.}, subject = {Biochemie}, language = {en} } @article{WeissSebald1978, author = {Weiss, H. and Sebald, Walter}, title = {Purification of cytochrome oxidase from Neurospora crassa and other sources}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-82082}, year = {1978}, abstract = {A chromatographic procedure 1 is described by means of which cytochrome oxidase has been purified from a variety of organisms including the fungus N eurospora crassa,2,3 the unicellular alga Po/ytoma mirum, 4 the insect Locusta migratoria ,5 the frog Xenopus muel/eri,4 and the mammal Rattus norwegicus. 4 This procedure can be used to equal effect for large-scale preparations, starting from grams of mitochondrial protein, or for small-scale preparations starting from milligrams. The cytochrome oxidase preparations from the different organisms are enzymically active. They show similar subunit compositions.}, subject = {Biochemie}, language = {en} } @article{SebaldMachleidtOtto1973, author = {Sebald, Walter and Machleidt, W. and Otto, J.}, title = {Products of mitochondrial protein synthesis in Neurospora crassa. Determination of equimolar amounts of three products in cytochrome oxidase on the basis of amino-acid analysis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62827}, year = {1973}, abstract = {Cytochrome oxidase isolated from N eurospora crassa was resolved into seven protein eomponents by eleetrophoresis in polyaerylamide gels eontaining sodium dodeeylsulfate. The apparent molecular weights were determined tobe 41000, 28500, 21000, 16000, 14000, 11500 and 10000 for the eomponents 1, 2, 3, 4, 5, 6, and 7, respectively. The components 1, 2 and 3 are synthesized on mitochondrial ribosomes as shown by the incorporation of radioactive amino aeids in the presenee of cyeloheximide. Amino-acidanalysis of the isolated components 1, 2 and 3 revealed a high content of apolar amino acids and a low eontent of basic amino aeids compared to an average amino-aeid eomposition of components 4-7. Components 1, 2 and 3 eontribute 27.9°/0, 18°/0 and 14.2°/0 to the whole eytoehrome oxidase protein. This was calculated from the contributions of the single eomponents to the totalleueine eontent of the enzyme and the leueine eontents (nmol leueine per mg protein) of the single eomponents as determined by amino-aeid analysis. Equimolar relations of the components 1, 2 and 3 are found by dividing the amounts of protein by their apparent molecular weights. A stoichiometry of 1:1:1 results assuming a minimal molecular weight of 150000 for the whole cytochrome oxidase protein. On the basis of the heme a content a molecular weight of about 70000 per heme group was determined, using an absorption coeffieient L1e605 (redueed minus oxidized) of 12 mM-1 cm-1• It is concluded that the smallest structural unit of eytochrome oxidase contains two heme groups.}, subject = {Biochemie}, language = {en} } @article{SchmidtWachterSebaldetal.1984, author = {Schmidt, B. and Wachter, E. and Sebald, Walter and Neupert, W.}, title = {Processing peptidase of Neurospora mitochondria. Two-step cleavage of imported ATPase subunit 9}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62674}, year = {1984}, abstract = {Subunit 9 (dicyclohexylcarbod{\"u}mide binding protein, 'proteolipid') of the mitochondrial F 1F0-ATPase is a nuclearly coded protein in Neurospora crassa. lt is synthesized on free cytoplasmic ribosomes as a larger precursor with an NH2-terminal peptide extension. The peptide extension is cleaved ofT after transport of the protein into the mitochondria. A processing activity referred to as processing peptidase that cleaves the precursor to subunit 9 and other mitochondrial proteins is described and characterized using a cell-free system. Precursor synthesized in vitro was incubated with extracts of mitochondria. Processing peptidase required Mn2 + for its activity. Localization studies suggested that it is a soluble component of the mitochondrial matrix. The precursor was cleaved in two sequential steps via an intermediate-sized polypeptide. The intermediate form in the processing of subunit 9 was also seen in vivo and upon import of the precursor into isolated mitochondria in vitro. The two dcavage sites in the precursor molecule were determined. The data indicate that: {a) the correct NH2-terminus of the mature protein was generated, (b) the NH2-terminal amino acid of the intermediate-sized polypeptide is isoleueine in position -31. The cleavage sites show similarity ofprimary structure. It is concluded that processing peptidase removes the peptide extension from the precursor to subunit 9 (and probably other precursors) after translocation of these polypeptides (or the NHrterminal part of these polypeptides) into the matrix space of mitochondria.}, subject = {Biochemie}, language = {en} } @article{SebaldNeupertWeiss1979, author = {Sebald, Walter and Neupert, W. and Weiss, H.}, title = {Preparation of Neurospora crassa mitochondria}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-82070}, year = {1979}, abstract = {The fungus Neurospora crassa represents a eukaryotic cell with high biosynthetic activities. Cell mass doubles in 2-4 hr during expone ntial growth , even in simple salt media with sucrose as the sole carbon source. The microorgani sm forms a mycelium of long hyphae durlng vegetative growth . The mitochondria can be isolated under relatively gentle condi tions since a few breaks in the threadlike hyphae are sufficient to cause the outflow of the organelles. This article describes two methods for the physical disruption of the hyphae : (I) The cell s are opened in a grind mill between two rotating corundum di sks. This is a continuous and fast procedure and allows large- and small-scale preparations of mitochondria. (2) Hyphae are ground with sand in a mortar and pestle. This procedure can be applied to microscale preparations of mitochondria starting with minute amounts of cells. Other procedures for the isolation of Neurospora mitochondria after the physical di sruption or the enzymatic degradation of the cell wall have been described elsewhere}, subject = {Biochemie}, language = {en} } @article{HenryHooversBarichardetal.1993, author = {Henry, Isabelle and Hoovers, Jan and Barichard, Fernande and Berth{\´e}as, Marie-Francoise and Puech, Anne and Prieur, Fabienne and Gessler, Manfred and Bruns, Gail and Mannens, Marcel and Junien, Claudine}, title = {Pericentric intrachromosomal insertion responsible for recurrence of del(11)(p13p14) in a family}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59157}, year = {1993}, abstract = {The combined use of qualitative and quantitative analysis of I I p I 3 polymorphic markers tagether with chromosomal in situ suppression hybridization (CISS) with biotin labeled probes mapping to I I p allowed us to characterize a complex rearrangement segregating in a family. We detected a pericentric intrachromosomal insertion responsible (or recurrence of del( I I )(p 13p 14) in the family: an insertion of band I I p 13-p 14 carrying the genes for predisposition to Wilms' tumor, WT I, and for aniridia, AN2, into the long arm of chromosome I I in II q 13-q 1<4. Asymptomatic balanced carriers were observed over three generations. Classical cytogenetics had failed to detect this anomaly in the balanced carriers, who were first considered to be somatic mosaics for del( II )(p 13). Two of these women gave birth to children carrying a deleted chromosome II. most likely resulting from the loss of the I I p 13 band inserted in I I q. Although in both cases the deletion encompassed exactly the same maternally inherited markers, there was a wide Variation in clinical expression. One child, with the karyotype 46,XY,del(ll)(pllpl4), presented the full-blown WAGR syndrome with anlridia, mental retardation, Wilms' tumor, and pseudohermaphroditism, but also had proteinuria and glomerular sclerosis reminiscent of Drash syndrome. In contrast, the other one, a girl with the karyotype 46,XX,del( I I )(p I 3), only had aniridia. Although a specific set of mutational sites has been observed in Drash patients, these findings suggest that the loss of one copy of the WTI gene can result in similar genital and kidney abnormalities.}, subject = {Biochemie}, language = {en} } @article{ArendsSebald1984, author = {Arends, H. and Sebald, Walter}, title = {Nucleotide sequence of the cloned mRNA and gene of the ADP/ATP carrier from Neurospora crassa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62684}, year = {1984}, abstract = {A cDNA complementary to the mRNA of the ADPIATP carrier from Neurospora crassa was identified among ordered cDNA clones by hybridizing total polyadenylated RNA to pools of 96 cDNA recombinant plasmids and subsequent cellfree translation of hybridization-selected mRNA. Further carrier cDNAs were found by colony fdter hybridization at a frequency of 0.2-0.3\%. The gene of the carrier was cloned and isolated on a 4.6-kbp EcoRl fragment of total Neurospora DNA, and the start of the mRNA was determined by Sl nuclease mapping. From the nucleotide sequence of the cDNA and the genomic DNA, the primary structure of the gene, of the mRNA and of the ADP I ATP carrier protein could be deduced. The gene occurs in a single copy in the genome and related genes are absent. It contains two short introns, and a pyrimidine-rieb promoter region. The mRNA has a 46-bp 5 1 end and a 219-bp 3 1 end. There is an open reading frame coding for the 313 amino acid residues of the Neurospora carrier protein. The amino acid sequence is homologous in 148 positions with the established primary structure of the beef heart carrier.}, subject = {Biochemie}, language = {en} } @article{GabelliniSebald1986, author = {Gabellini, N. and Sebald, Walter}, title = {Nucleotide sequence and transcription of the fbc operon from Rhodopseudomonas sphaeroides. Evaluation of the deduced amino acid sequences of the FeS protein, cytochrome b and cytochrome c\(_1\)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62615}, year = {1986}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{ReuschArnoldHeusseretal.1994, author = {Reusch, P. and Arnold, S. and Heusser, C. and Wagner, K. and Weston, B. and Sebald, Walter}, title = {Neutralizing monoclonal antibodies define two different functional sites in human interleukin-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62418}, year = {1994}, abstract = {Human interleukin-4 (IL-4) is a small four-helix-bundle protein which is essential for organizing defense reactions against macroparasites, in particular helminths. Human IL-4 also appears to exert a pathophysiological role during various IgE-mediated allergic diseases. Seven different monoclonal antibodies neutralizing the activity of human IL-4 were studied in order to identify functionally important epitopes. A collection of 41 purified IL-4 variants was used to analyse how defined amino acid replacements affect binding affinity for each individual mAb. Specific amino acid positions could be assigned to four different epitopes. mAbs recognizing epitopes on helix A and/or C interfered with IL-4 receptor binding and thus inhibited IL-4 function. However, other mAbs also inhibiting IL-4 function recognized an epitope on helix D of IL-4 and did not inhibit IL-4 binding to the receptor protein. One mAb, recognizing N-terminal and C-terminal residues, partially competed for binding to the receptor. The results of these mAb epitope analyses confirm and extend previous data on the functional consequences of the amino acid replacements which showed that amino acid residues in helices A and C of IL-4 provide a binding site for the cloned IL-4 receptor and that a signalling site in helix D interacts with a further receptor protein.}, subject = {Biochemie}, language = {en} } @article{WeigelMeyerSebald1989, author = {Weigel, U. and Meyer, M. and Sebald, Walter}, title = {Mutant proteins of human interleukin 2. Renaturation yield, proliferative activity and receptor binding}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62543}, year = {1989}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{GesslerBruns1988, author = {Gessler, Manfred and Bruns, Gail A. P.}, title = {Molecular mapping and cloning of the breakpoints of a chromosome 11p14.1-p13 deletion associated with the AGR syndrome}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59264}, year = {1988}, abstract = {Chromosome 11p13 is frequently rearranged in individuals with the WAGR syndrome (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) or parts of this syndrome. To map the cytogenetic aberrations molecularly, we screened DNA from cell Unes with known WAGR-related chromosome abnormalities for rearrangements with pulsed fleld gel (PFG) analysis using probes deleted from one chromosome 11 homolog of a WAGR patient. The first alteration was detected in a cell line from an individual with aniridia, genitourinary anomalies, mental retardation, and a deletion described as 11p14.1-p13. We have located one breakpoint close to probe HU11-164B and we have cloned both breakpoint sites as well as the junctional fragment. The breakpoints subdivide current intervals on the genetic map, and the probes for both sides will serve as important additional markers for a long-range restriction map of this region. Further characterization and sequencing of the breakpoints may yield insight into the mechanisms by which these deletions occur.}, subject = {Biochemie}, language = {en} } @phdthesis{Kober2012, author = {Kober, Franz-Xaver Wilhelm}, title = {Molecular insights into the protein disulfide isomerase family}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72144}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2012}, abstract = {Upon synthesis, nascent polypeptide chains are subject to major rearrangements of their side chains to obtain an energetically more favorable conformation in a process called folding. About one third of all cellular proteins pass through the secretory pathway and undergo oxidative folding in the endoplasmic reticulum (ER). During oxidative folding, the conformational rearrangements are accompanied by the formation of disulfide bonds - covalent bonds between cysteine side chains that form upon oxidation. Protein disulfide isomerase (PDI) assists in the folding of substrates by catalyzing the oxidation of pairs of cysteine residues and the isomerization of disulfide bonds as well as by acting as chaperones. In addition to PDI itself, a family of related ER-resident proteins has formed. All PDI family members share the thioredoxin fold in at least one of their domains and exhibit a subset of the PDI activities. Despite many studies, the role of most PDI family members remains unclear. The project presented in this thesis was aimed to establish tools for the biochemical characterization of single members of the PDI family and their role in the folding process. A combination of fluorescence based assays was developed to selectively study single functions of PDI family members and relate their properties of either catalysis of oxidation or catalysis of isomerization or chaperone activity to the rest of the protein family. A binding assay using isothermal titration calorimetry (ITC) was established to complement the activity assays. Using ITC we could show for the first time that members of the PDI family can distinguish between folded and unfolded proteins selectively binding the latter. The unique information provided by this method also revealed a two-site binding of unfolded proteins by PDI itself. In addition to the functional characterization, experiments were conducted to further investigate the oligomeric state of PDI. We could show that the equilibrium between structurally different states of PDI is heavily influenced by the redox state of the protein and its environment. This new data could help to further our understanding of the interplay between oxidases like PDI and their regenerative enzymes like Ero1, which may be governed by structural changes in response to the change in redox status. Another structural approach was the screening of all investigated PDI family members for suitable crystallization conditions. As a result of this screening we could obtain protein crystals of human ERp27 and were able to solve the structure of this protein with X-ray crystallography. The structure gives insight into the mechanisms of substrate binding domains within the PDI family and helps to understand the interaction of ERp27 with the redox active ERp57. In collaboration with the group of Heike Hermanns we could further show the physiological importance of this interaction under oxidative stress. In conclusion, the project presented in this thesis provides novel tools for an extensive analysis of the activities of single PDI family members as well as a useful set of methods to characterize novel oxidoreductases and chaperones. The initial results obtained with the our novel methods are very promising. At the same time, the structural approach of this project could successfully solve the structure of a PDI family member and give information about the interplay within the PDI family.}, subject = {Biochemie}, language = {en} } @article{KleenePfannerPfalleretal.1987, author = {Kleene, R. and Pfanner, N. and Pfaller, R. and Link, T. A. and Sebald, Walter and Neupert, W. and Tropschug, M.}, title = {Mitochondrial porin of Neurospora crassa: cDNA cloning, in vitro expression and import into mitochondria}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62566}, year = {1987}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{TzagoloffMacinoSebald1979, author = {Tzagoloff, A. and Macino, G. and Sebald, Walter}, title = {Mitochondrial genes and translation products}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47408}, year = {1979}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{SebaldWild1979, author = {Sebald, Walter and Wild, G.}, title = {Mitochondrial ATPase complex from Neurospora crassa}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-82065}, year = {1979}, abstract = {The A TPase eomplex has been isolated from mitoehondria of N eurospora crassa by immunologieal teehniques. The protein ean be obtained rapidly and qua ntitatively in high purity by miero- or large-seale immunopreeipitation. Immunopreeipitation has been applied to labeled and doubly labeled mitoehondrial proteins in order to investigate the number and moleeular weights of subunit polypeptides , the site of synthesis of subunit polypeptides, and the dieycIohexyIcarbodiimide-binding protein . The A TPase complex obtained by large-seale immunopreeipitation has been used as starting ma terial for the isolation of hydrophobie polypeptides.}, subject = {Biochemie}, language = {en} } @article{HoppeGattiWeberetal.1986, author = {Hoppe, J. and Gatti, D. and Weber, H. and Sebald, Walter}, title = {Labeling of individual amino acid residues in the membrane-embedded F\(_0\) part of the F\(_1\) F\(_0\) ATP synthase from Neurospora crassa. Influence of oligomycin and dicyclohexylcarbodiimide}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62598}, year = {1986}, abstract = {Three F0 subunits and the F\(_1\) subunit P of the ATP synthase from Neurospora crassa were labeled with the lipophilic photoactivatable reagent 3-(trifluoromethyl)-3-(m-[\(^{125}\)I]iodophenyl)diazirine ([\(^{125}\)I]TID). In the proteolipid subunit which was the most heavily labeled polypeptide labeling was confmed to five residues at the NH2-terminus and five residues at the C-terminus ofthe protein. Labeling occurred at similar positions compared with the homologaus protein (subunit c) in the ATP synthase from Escherichia coli, indicating a similar structure of the proteolipid subunits in their respective organisms. The inhibitors oligomycin and dicyclohexylcarbodiimide did not change the pattern of accessible surface residues in the proteolipid, suggesting that neither inhibitor induces gross conformational changes. However, in the presence of oligomycin, the extent oflabeling in some residues was reduced. Apparently, these residues provide part of the binding site for the inhibitor. After reaction with dicyclohexylcarbodiimide an additional labeled amino acid was found at position 65 corresponding to the invariant carbod{\"u}mide-binding glutamic acid. These results and previous observations indicate that the carboxyl side chain of Glu-65 is located at the protein-lipid interphase. The idea is discussed that proton translocation occurs at the interphase between different types if F\(_0\) subunits. Dicyclohexylcarbodiimide or oligomycin might disturb this essential interaction between the F\(_0\) subunits.}, subject = {Biochemie}, language = {en} } @article{LindenmaierDittmarHauseretal.1985, author = {Lindenmaier, W. and Dittmar, K. E. and Hauser, H. and Necker, A. and Sebald, Walter}, title = {Isolation of a functional human interleukin 2 gene from a cosmid library by recombination in vivo}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62662}, year = {1985}, abstract = {A method has been developed that allows the isolation of genomic clones from a cosmid library by homologaus recombination in vivo. This method was used to isolate a human genomic interleukin 2 (IL2) gene. The genomic cosmid library was packaged in vivo into A. phage particles. A recombination-proficient host strain carrying IL2 cDNA sequences in a non-homologaus plasmid vector was infected by the packaged cosmid library. After in vivo packaging and reinfection, recombinants carrying the antibiotic resistance genes of both vectors were selected. From a recombinant cosmid clone the chromosomal IL2 genewas restored. After DNA mediated gene transfer into mouse Ltk- cells human IL2 was expressed constitutively.}, subject = {Biochemie}, language = {en} } @article{SebaldNeupertBirkmayer1970, author = {Sebald, Walter and Neupert, W. and Birkmayer, G. D.}, title = {Internal and external contributions to the biogenesis of mitochondrial proteins}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62876}, year = {1970}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} } @article{PreiserSchmartzVanderLindenetal.1991, author = {Preiser, J. C. and Schmartz, D. and Van der Linden, P. and Content, J. and Vanden Bussche, P. and Buurman, W. and Sebald, Werner and Dupont, E. and Pinsky, M. R. and Vincent, J. L.}, title = {Interleukin-6 administration has no acute hemodynamic or hematologic effect in the dog}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62511}, year = {1991}, abstract = {To investigate the possible hemodynamic efl'ects of interleukin-6 (IL-6), a single dose of 15 mcg/kg of recombinant IL-6 isolated from Escherichia coli was injected intravenously in six pentobarbital-anesthetized dogs. After 30 min, saline infusion was performed to maintain the - pulmonary artery balloon-occluded pressure at baseline Ievel. The animals were observed for up to 5 hours. No other hemodynamic alteration was observed than a gradual decline in cardiac output attributed to anesthesia. Hematologic variables, blood glucose, and total serum proteins were also constant. IL-6 levels were markedly elevated in the blood, bot no tumor necrosis factor activity was detected. Thus a primary role for IL-6 in the early cardiovascular alterations associated with septic shock seems unlikely.}, subject = {Biochemie}, language = {en} } @article{LehrnbecherPootOrschescheketal.1994, author = {Lehrnbecher, T. and Poot, M. and Orscheschek, K. and Sebald, Walter and Feller, A. C. and Merz, H.}, title = {Interleukin 7 as interleukin 9 drives phytohemagglutinin-activated T cells through several cell cycles; no synergism between interleukin 7, interleukin 9 and interleukin 4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62438}, year = {1994}, abstract = {The effects of the interlenkins IL-7 and IL-9 on cell cycle progression were investigated by conventional [3H]thymidine incorporation and by the bivariate BrdU/Hoechst technique. 8oth IL· 7 and IL-9 drive phytohemagglutinin-activated T cells through more than one cell cycle, but IL-7 wasmorepotent on cell cycle progression than IL-9. Neither synergistic nor inhibitory effects were seen between various combinations of the lymphokines IL-7, IL-9 and IL-4 compared to each lymphokine alone. When T cells are activated with phytohemagglutinin for 3 days, all or most IL-4 responsive cells respond to IL-7 as weil, whereas only a part of IL-7 responders are IL-4 responders. In contrast, when T cells are activated with phytohemagglutinin for 7 days, the quantitative data of the cell cycle distribution soggest that the population of IL-7 responders is at least an overlapping, if not a real subset of the population of the IL-4 responders.}, subject = {Biochemie}, language = {en} } @article{LehrnbecherMerzSebaldetal.1991, author = {Lehrnbecher, T. and Merz, H. and Sebald, Walter and Poot, M.}, title = {Interleukin 4 drives phytohemagglutinin-activated T cells through several cell cycles: no synergism between interleukin 2 and interleukin 4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62491}, year = {1991}, abstract = {Cell kinetic studies of T cells stimulated with the interleukin 2 (11-2), D-4, or both lymphokines were performed with conventional [3H] thymidine incorporation and with the bivariate BrdU/Hoechst technique. 11-2 and 11-4 are able to drive phytohemagglutininactivated T cells through more than one cell cycle. Neither synergistic nor inhibitory efl'ect on T -cell proliferationwas seen for the stimulation with both 11-2 and 11-4 as compared with the effect ofll-2 alone. The quantitative data ofthe cell cycle distribution ofphytohemagglutininactivated T cells suggestthat the population ofll-4-responsive cells is at least an overlapping population, if not a real subset of the ·population of the 11-2-responsive cells.}, subject = {Biochemie}, language = {en} } @article{SebaldWeissJackl1972, author = {Sebald, Walter and Weiss, H. and Jackl, G.}, title = {Inhibition of the assembly of cytochrome oxidase in Neurospora crassa by chloramphenicol}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62852}, year = {1972}, abstract = {Cytochrome oxidasewas prepared from Neurospora crassa by chromatography on oleyl polymethacrylic acid resin and separated into seven polypeptides by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate. Incorporation oflabelled amino acids into the single polypeptideswas investigated after a pulse labelling in the absence and presence of chloramphenicol, and afterwashing out the inhibitor. Chloramphenicol (4 mg/ml) inhibited amino acid incorporation into all polypeptides 90-95\%• while labeHing of the whole membrane protein was inhibited only 30\%• Mter washing out the inhibitor and further growth of the cells. the four smaller polypeptides were highly labelled, whereas the other polypeptides showed only a. small increase in radioactivity. It is concluded that the four small-sized polypeptides of cytochrome oxidase are synthesized but not integrated into the functional enzyme under the action of chloramphenicol.}, subject = {Biochemie}, language = {en} } @article{SebaldHofstoetterHackeretal.1969, author = {Sebald, Walter and Hofst{\"o}tter, T. and Hacker, D. and B{\"u}cher, T.}, title = {Incorporation of amino acids into mitochondrial protein of the flight muscle of Locusta migratoria in vitro and in vivo in the presence of cycloheximide}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62919}, year = {1969}, abstract = {No abstract available}, subject = {Biochemie}, language = {en} }