TY  - JOUR
A1  - Siegl, Christine
A1  - Prusty, Bhupesh K.
A1  - Karunakaran, Karthika
A1  - Wischhusen, Jörg
A1  - Rudel, Thomas
T1  - Tumor Suppressor p53 Alters Host Cell Metabolism to Limit Chlamydia trachomatis Infection
JF  - Cell Reports
N2  - Obligate intracellular bacteria depend entirely on nutrients from the host cell for their reproduction. Here, we show that obligate intracellular Chlamydia downregulate the central tumor suppressor p53 in human cells. This reduction of p53 levels is mediated by the PI3K-Akt signaling pathway, activation of HDM2, and subsequent proteasomal degradation of p53. The stabilization of p53 in human cells severely impaired chlamydial development and caused the loss of infectious particle formation. DNA-damage-induced p53 interfered with chlamydial development through downregulation of the pentose phosphate pathway (PPP). Increased expression of the PPP key enzyme glucose-6-phosphate dehydrogenase rescued the inhibition of chlamydial growth induced by DNA damage or stabilized p53. Thus, downregulation of p53 is a key event in the chlamydial life cycle that reprograms the host cell to create a metabolic environment supportive of chlamydial growth.
KW  - chlamydia trachomatis
KW  - tumor
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-118200
SN  - 2211-1247
VL  - 9
IS  - 3
ER  - 
TY  - JOUR
A1  - Haake, Markus
A1  - Haack, Beatrice
A1  - Schäfer, Tina
A1  - Harter, Patrick N.
A1  - Mattavelli, Greta
A1  - Eiring, Patrick
A1  - Vashist, Neha
A1  - Wedekink, Florian
A1  - Genssler, Sabrina
A1  - Fischer, Birgitt
A1  - Dahlhoff, Julia
A1  - Mokhtari, Fatemeh
A1  - Kuzkina, Anastasia
A1  - Welters, Marij J. P.
A1  - Benz, Tamara M.
A1  - Sorger, Lena
A1  - Thiemann, Vincent
A1  - Almanzar, Giovanni
A1  - Selle, Martina
A1  - Thein, Klara
A1  - Späth, Jacob
A1  - Gonzalez, Maria Cecilia
A1  - Reitinger, Carmen
A1  - Ipsen-Escobedo, Andrea
A1  - Wistuba-Hamprecht, Kilian
A1  - Eichler, Kristin
A1  - Filipski, Katharina
A1  - Zeiner, Pia S.
A1  - Beschorner, Rudi
A1  - Goedemans, Renske
A1  - Gogolla, Falk Hagen
A1  - Hackl, Hubert
A1  - Rooswinkel, Rogier W.
A1  - Thiem, Alexander
A1  - Romer Roche, Paula
A1  - Joshi, Hemant
A1  - Pühringer, Dirk
A1  - Wöckel, Achim
A1  - Diessner, Joachim E.
A1  - Rüdiger, Manfred
A1  - Leo, Eugen
A1  - Cheng, Phil F.
A1  - Levesque, Mitchell P.
A1  - Goebeler, Matthias
A1  - Sauer, Markus
A1  - Nimmerjahn, Falk
A1  - Schuberth-Wagner, Christine
A1  - Felten, Stefanie von
A1  - Mittelbronn, Michel
A1  - Mehling, Matthias
A1  - Beilhack, Andreas
A1  - van der Burg, Sjoerd H.
A1  - Riedel, Angela
A1  - Weide, Benjamin
A1  - Dummer, Reinhard
A1  - Wischhusen, Jörg
T1  - Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment
JF  - Nature Communications
N2  - Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don’t respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/β2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development.
KW  - cancer microenvironment
KW  - immunotherapy
KW  - T cells
KW  - tumour immunology
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-357333
VL  - 14
ER  - 
TY  - THES
A1  - Brändlein, Stephanie
T1  - Tumorimmunität: Spezifität, Genetik und Funktion natürlicher IgM-Antikörper
T1  - Tumorimmunity: Specificity, Genetics and Function of natural IgM antibodies
N2  - Die Entstehung maligner Zellen durch irreversible genetische Veränderungen ist ein allgegenwärtiger Prozess im menschlichen Organismus. Allein die spontane Mutationsrate genügt um in einem Organismus permanent transformierte Zellen entstehen zu lassen, welche den Körper in kürzester Zeit überschwemmen würden. Auch wenn bestimmte genetische Schäden frühzeitig durch Reparaturmechanismen beseitigt werden und sich nicht jede transformierte Zelle in einem Tumor manifestiert, so ist die eigentliche Frage nicht, warum Krebs entsteht, sondern warum er bei der hohen Mutationsrate so selten auftritt. Verantwortlich für die frühe Erkennung und Beseitigung transformierter Zellen ist das körpereigene Immunsystem, das in der Lage ist die meisten aberranten Zellen zu entfernen, sodass der manifeste Tumor die Ausnahme und nicht die Regel ist. Der menschliche Organismus verfügt über ein angeborenes und ein erworbenes Immunsystem. Bis heute ist nicht eindeutig geklärt, ob maligne Zellen mit ihren veränderten Oberflächenstrukturen erst eine Immunantwort induzieren müssen oder ob, wie bei der Abwehr infektiöser Partikel, die angeborene Immunität für die Beseitigung von Tumorzellen verantwortlich ist. Die in dieser Arbeit verwendete humane Hybridoma Technologie (Immortalisierung menschlicher Lymphozyten und Isolierung monoklonaler Antikörper) bietet die einzigartige Möglichkeit, sowohl aus an Krebs erkrankten Patienten als auch aus gesunden Probanden tumorspezifische Antikörper zu isolieren und durch deren genauere Charakterisierung Einblicke in die humorale Immunität gegen maligne Zellen zu erhalten. In der vorliegenden Arbeit werden fünf humane monoklonale Antikörper beschrieben, die aus verschiedenen Tumorpatienten gewonnen wurden, sowie zwei Antikörper, die aus gesunden Probanden isoliert werden konnten. In allen Fällen erwiesen sich die Antikörper als tumorspezifisch, d.h. sie reagieren nicht mit gesundem Gewebe und sind demnach keine Autoantikörper. Es handelt sich weiterhin in allen Fällen um Antikörper des IgM-Isotyps; es konnten keinen Antikörper anderer Ig-Klassen isoliert werden. Genetische Analysen ergaben, dass alle isolierten Antikörper gering oder gar nicht mutiert waren, was bedeutet, dass sie nicht durch Stimulation affinitätsgereift sind. Zudem konnte demonstriert werden, dass alle Antikörper Apoptose von Tumorzellen induzieren und dass sie an eine Zuckerkette ihrer Antigene binden oder solche Carbohydrate zumindest entscheidend in die Bindung involviert sind. Die Eigenschaften der in dieser Arbeit beschriebenen Antikörper wurden mit anderen bereits etablierten IgM-Antikörpern verglichen. Hierbei stellte sich heraus, dass alle Antikörper, welche sich als tumorspezifisch erwiesen, ähnliche Eigenschaften zeigen. Interessant ist zudem die Beobachtung, dass die Keuzreaktion der Antikörper, also ihre Reaktion mit anderen Tumorgeweben, reziprok mit dem Mutations-grad korreliert ist. Je mehr Mutationen ein Antikörper aufweist, desto eingeschränkter und spezifischer sind demnach seine Reaktionen mit anderen Tumoren. Dies deutet darauf hin, dass auch innerhalb der Keimbahn-kodierten Antikörper durch vereinzelte Mutationen eine höhere Variabilität erzeugt werden kann. Ähnlich wie bei der Affinitätsreifung der erworbenen Immunität scheint sich auch hier die Spezifität mit der Anzahl der Mutationen zu erhöhen. Zusammenfassend weisen die erhaltenen Ergebnisse darauf hin, dass zumindest die humorale Immunität gegen maligne Zellen das Resultat der angeborenen Immunität ist und nicht von Tumorzellen induziert wird. Dies bedeutet zudem, dass Moleküle wie natürliche Antikörper in der Immunität eine viel größere Rolle spielen als bisher angenommen. Ähnliche Ergebnisse wurden bereits bei der Untersuchung der Immunität gegen bakterielle Antigene erzielt, sodass hier vermutet werden kann, dass die gleichen Mechanismen zugrunde liegen wie bei der Abwehr transformierter Zellen. Darüber hinaus wird die Frage beantwortet, warum ein manifester Tumor eine Ausnahme bleibt. Die angeborene, primäre Immunität verfügt über ein existierendes Repertoire an Rezeptoren, welche eine ausreichende Variabilität aufweisen, und muss daher nicht erst über ein komplexes System von Erkennung und Stimulation, wie die adaptierte Immunität, induziert werden. Dieser logistische Vorsprung der natürlichen Immunität garantiert eine permanente Überwachung und eine schnelle Reaktion gegenüber veränderten Zellen und fremden Partikeln.
N2  - The formation of malignant cells through irreversible genetic alterations is a chronic process in a human organism. The spontaneous mutation rate is high enough to let transformed cells arise permanently in an organism and to flood the body with these cells in a short period of time. Although specific genetic damages were eliminated very early by repair mechanisms and not every transformed cell became a manifest tumour, the major question to be answered is not why cancer arises but why it occurs so infrequently despite of the high mutation rate. The immune system is responsible for the early detection and elimination of transformed cells. It is able to remove most of the transformed cells so that tumour formation is the exception but not the rule. The immune system of the human organism consists of an innate and an acquired system. Until the present time it is not explained definitely, whether malignant cells with their altered surface structure have to induce an immune answer or if the innate immunity is responsible for the elimination of tumour cells like for infectious particles. In this dissertation the human hybridoma technology (immortalisation of human lymphocytes and isolation of human monoclonal antibodies) was used to investigate this question. This technique offers the unique possibility to isolate tumour-specific antibodies from cancer patients as well as from healthy persons and to attain additionally insights into the humoral immunity against malignant cells. Five human monoclonal antibodies were described which were isolated from different cancer patients and in addition two antibodies obtained from healthy donors. In all of the cases the antibodies prove to be tumour-specific which means they do not react with healthy tissues and are according to this no auto-antibodies. All of them are IgM antibodies, no tumour-specific IgA or IgG antibody was detectable. Genetic analysis show that all isolated antibodies were only slightly mutated or not mutated at all, which means that they were not affinity-maturated due to antigen stimulation. Furthermore it was possible to demonstrate that all isolated tumour-specific IgM antibodies induce apoptosis in tumour cells. Another result indicates that carbohydrates are involved in the binding of the antibodies to their corresponding antigen. The characteristics of the antibodies were compared with other IgM antibodies which were already established in our lab. Here all antibodies which prove to be tumour-specific show similar characteristics. Interestingly the amount of cross reactivity with other tumour tissues correlates reciprocally with the degree of mutations. The more mutations an antibody displays the more reduced are the reactions with other tumour tissues. This indicates that, similar to the affinity-maturation of adapted immunity, an increase of specificity and most likely also variability of germ-line coded antibodies can be generated by few mutations. Our observations indicate that the humoral immunity against malignant cells is the result of the innate immunity. This means moreover that molecules like natural antibodies play a much more important role in immunity than assumed so far. Similar results were obtained already with analysis of immunity against bacterial antigens. This leads to the assumption that here the same mechanisms are involved like in the defence against transformed cells. Moreover the question could be answered why a manifest tumour remains an exception. The innate, primary immunity has an existing repertoire of receptors which are variable enough so that a complex system of recognition and stimulation like in the acquired immunity does not have to be induced. This logistic advantage of the natural immunity guarantees a permanent control and a fast reaction towards altered cells and foreign particles.
KW  - Tumorimmunologie
KW  - Immunglobulin M
KW  - Tumorimmunität
KW  - natürliche IgM-Antikörper
KW  - Tumorimmunity
KW  - natural IgM antibodies
Y1  - 2003
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-6661
ER  - 
TY  - JOUR
A1  - Kruse, N.
A1  - Shen, B. J.
A1  - Arnold, S.
A1  - Tony, H. P.
A1  - Müller, T.
A1  - Sebald, Walter
T1  - Two distinct functional sites of human interleukin 4 are identified by variants impaired in either receptor binding or receptor activation
N2  - 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.
KW  - Biochemie
KW  - drug design/partial agonists
KW  - receptor signalling
Y1  - 1993
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-62451
ER  - 
TY  - JOUR
A1  - Maschwitz, Ulrich
A1  - Fiala, Brigitte
A1  - Moog, J.
A1  - Saw, L. G.
T1  - Two new myrmecophytic associations from the Malay Peninsula: ants of the genus Cladomyrma as partners of Saraca thaipingensis and Crypteronia griffithii
N2  - In Peninsular Malaysia the trees Saraca thaipingensis (Caesalpiniaceae) and Crypteronia griffithii (Crypteroniaceae) are inhabited by ants. In the vicinity ofGombak, near Kuala Lumpur, the hollow internodes of young Saraca thaipingensis plants are colonized mainly by two Cladomyrma species. In larger trees a Crematogaster sp. is also found. Crypteronia griffithii is inhabited by a third species of Cladomyrma. None of these species is conspecific with any of the three Cladomyrma taxa so far described. The colonies are founded by single mated queens, which have a conspicuous, sphecid wasp-like behaviour when searching for host plants and nest sites. They chew holes into the plant intern odes and hollow them out to provide nest sites. Coccids and pseudococcids are cultivated within the internodes. The homopterans are not carried by queens on their nuptial flights. They apparently find their way by themselves into the cavities or are perhaps carried there by the worker ants. The Cladomyrma ants on Crypteronia are not aggressive, in contrast to those on Saraca thaipingensis. The relationship of Crypteronia with ants seems to be obligatory, whereas Saraca was only partly colonized by Cladomyrma. The interaction of Saraca with Crematogaster sp. is loose and facultative, since the Crematogaster sp. also lives on other tree species. Our studies have now revealed four Cladomyrma spp. which are regularly associated with plants. The genus therefore seems to have an entirely myrmecophytic way of life.
KW  - Myrmecophytism ; Malaysia ; trophobionts ; colony foundation ; Cladomyrma
Y1  - 1991
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32992
ER  - 
TY  - JOUR
A1  - Dörk, Thilo
A1  - Peterlongo, Peter
A1  - Mannermaa, Arto
A1  - Bolla, Manjeet K.
A1  - Wang, Qin
A1  - Dennis, Joe
A1  - Ahearn, Thomas
A1  - Andrulis, Irene L.
A1  - Anton-Culver, Hoda
A1  - Arndt, Volker
A1  - Aronson, Kristan J.
A1  - Augustinsson, Annelie
A1  - Beane Freeman, Laura E.
A1  - Beckmann, Matthias W.
A1  - Beeghly-Fadiel, Alicia
A1  - Behrens, Sabine
A1  - Bermisheva, Marina
A1  - Blomqvist, Carl
A1  - Bogdanova, Natalia V.
A1  - Bojesen, Stig E.
A1  - Brauch, Hiltrud
A1  - Brenner, Hermann
A1  - Burwinkel, Barbara
A1  - Canzian, Federico
A1  - Chan, Tsun L.
A1  - Chang-Claude, Jenny
A1  - Chanock, Stephen J.
A1  - Choi, Ji-Yeob
A1  - Christiansen, Hans
A1  - Clarke, Christine L.
A1  - Couch, Fergus J.
A1  - Czene, Kamila
A1  - Daly, Mary B.
A1  - dos-Santos-Silva, Isabel
A1  - Dwek, Miriam
A1  - Eccles, Diana M.
A1  - Ekici, Arif B.
A1  - Eriksson, Mikael
A1  - Evans, D. Gareth
A1  - Fasching, Peter A.
A1  - Figueroa, Jonine
A1  - Flyger, Henrik
A1  - Fritschi, Lin
A1  - Gabrielson, Marike
A1  - Gago-Dominguez, Manuela
A1  - Gao, Chi
A1  - Gapstur, Susan M.
A1  - García-Closas, Montserrat
A1  - García-Sáenz, José A.
A1  - Gaudet, Mia M.
A1  - Giles, Graham G.
A1  - Goldberg, Mark S.
A1  - Goldgar, David E.
A1  - Guenél, Pascal
A1  - Haeberle, Lothar
A1  - Haimann, Christopher A.
A1  - Håkansson, Niclas
A1  - Hall, Per
A1  - Hamann, Ute
A1  - Hartman, Mikael
A1  - Hauke, Jan
A1  - Hein, Alexander
A1  - Hillemanns, Peter
A1  - Hogervorst, Frans B. L.
A1  - Hooning, Maartje J.
A1  - Hopper, John L.
A1  - Howell, Tony
A1  - Huo, Dezheng
A1  - Ito, Hidemi
A1  - Iwasaki, Motoki
A1  - Jakubowska, Anna
A1  - Janni, Wolfgang
A1  - John, Esther M.
A1  - Jung, Audrey
A1  - Kaaks, Rudolf
A1  - Kang, Daehee
A1  - Kapoor, Pooja Middha
A1  - Khusnutdinova, Elza
A1  - Kim, Sung-Won
A1  - Kitahara, Cari M.
A1  - Koutros, Stella
A1  - Kraft, Peter
A1  - Kristensen, Vessela N.
A1  - Kwong, Ava
A1  - Lambrechts, Diether
A1  - Le Marchand, Loic
A1  - Li, Jingmei
A1  - Lindström, Sara
A1  - Linet, Martha
A1  - Lo, Wing-Yee
A1  - Long, Jirong
A1  - Lophatananon, Artitaya
A1  - Lubiński, Jan
A1  - Manoochehri, Mehdi
A1  - Manoukian, Siranoush
A1  - Margolin, Sara
A1  - Martinez, Elena
A1  - Matsuo, Keitaro
A1  - Mavroudis, Dimitris
A1  - Meindl, Alfons
A1  - Menon, Usha
A1  - Milne, Roger L.
A1  - Mohd Taib, Nur Aishah
A1  - Muir, Kenneth
A1  - Mulligan, Anna Marie
A1  - Neuhausen, Susan L.
A1  - Nevanlinna, Heli
A1  - Neven, Patrick
A1  - Newman, William G.
A1  - Offit, Kenneth
A1  - Olopade, Olufunmilayo I.
A1  - Olshan, Andrew F.
A1  - Olson, Janet E.
A1  - Olsson, Håkan
A1  - Park, Sue K.
A1  - Park-Simon, Tjoung-Won
A1  - Peto, Julian
A1  - Plaseska-Karanfilska, Dijana
A1  - Pohl-Rescigno, Esther
A1  - Presneau, Nadege
A1  - Rack, Brigitte
A1  - Radice, Paolo
A1  - Rashid, Muhammad U.
A1  - Rennert, Gad
A1  - Rennert, Hedy S.
A1  - Romero, Atocha
A1  - Ruebner, Matthias
A1  - Saloustros, Emmanouil
A1  - Schmidt, Marjanka K.
A1  - Schmutzler, Rita K.
A1  - Schneider, Michael O.
A1  - Schoemaker, Minouk J.
A1  - Scott, Christopher
A1  - Shen, Chen-Yang
A1  - Shu, Xiao-Ou
A1  - Simard, Jaques
A1  - Slager, Susan
A1  - Smichkoska, Snezhana
A1  - Southey, Melissa C.
A1  - Spinelli, John J.
A1  - Stone, Jennifer
A1  - Surowy, Harald
A1  - Swerdlow, Anthony J.
A1  - Tamimi, Rulla M.
A1  - Tapper, William J.
A1  - Teo, Soo H.
A1  - Terry, Mary Beth
A1  - Toland, Amanda E.
A1  - Tollenaar, Rob A. E. M.
A1  - Torres, Diana
A1  - Torres-Mejía, Gabriela
A1  - Troester, Melissa A.
A1  - Truong, Thérèse
A1  - Tsugane, Shoichiro
A1  - Untch, Michael
A1  - Vachon, Celine M.
A1  - van den Ouweland, Ans M. W.
A1  - van Veen, Elke M.
A1  - Vijai, Joseph
A1  - Wendt, Camilla
A1  - Wolk, Alicja
A1  - Yu, Jyh-Cherng
A1  - Zheng, Wei
A1  - Ziogas, Argyrios
A1  - Ziv, Elad
A1  - Dunnig, Alison
A1  - Pharaoh, Paul D. P.
A1  - Schindler, Detlev
A1  - Devilee, Peter
A1  - Easton, Douglas F.
T1  - Two truncating variants in FANCC and breast cancer risk
JF  - Scientific Reports
N2  - Fanconi anemia (FA) is a genetically heterogeneous disorder with 22 disease-causing genes reported to date. In some FA genes, monoallelic mutations have been found to be associated with breast cancer risk, while the risk associations of others remain unknown. The gene for FA type C, FANCC, has been proposed as a breast cancer susceptibility gene based on epidemiological and sequencing studies. We used the Oncoarray project to genotype two truncating FANCC variants (p.R185X and p.R548X) in 64,760 breast cancer cases and 49,793 controls of European descent. FANCC mutations were observed in 25 cases (14 with p.R185X, 11 with p.R548X) and 26 controls (18 with p.R185X, 8 with p.R548X). There was no evidence of an association with the risk of breast cancer, neither overall (odds ratio 0.77, 95%CI 0.44–1.33, p = 0.4) nor by histology, hormone receptor status, age or family history. We conclude that the breast cancer risk association of these two FANCC variants, if any, is much smaller than for BRCA1, BRCA2 or PALB2 mutations. If this applies to all truncating variants in FANCC it would suggest there are differences between FA genes in their roles on breast cancer risk and demonstrates the merit of large consortia for clarifying risk associations of rare variants.
KW  - oncology
KW  - risk factors
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-222838
VL  - 9
ER  - 
TY  - JOUR
A1  - Schubert, Jonathan
A1  - Schulze, Andrea
A1  - Prodromou, Chrisostomos
A1  - Neuweiler, Hannes
T1  - Two-colour single-molecule photoinduced electron transfer fluorescence imaging microscopy of chaperone dynamics
JF  - Nature Communications
N2  - Many proteins are molecular machines, whose function is dependent on multiple conformational changes that are initiated and tightly controlled through biochemical stimuli. Their mechanistic understanding calls for spectroscopy that can probe simultaneously such structural coordinates. Here we present two-colour fluorescence microscopy in combination with photoinduced electron transfer (PET) probes as a method that simultaneously detects two structural coordinates in single protein molecules, one colour per coordinate. This contrasts with the commonly applied resonance energy transfer (FRET) technique that requires two colours per coordinate. We demonstrate the technique by directly and simultaneously observing three critical structural changes within the Hsp90 molecular chaperone machinery. Our results reveal synchronicity of conformational motions at remote sites during ATPase-driven closure of the Hsp90 molecular clamp, providing evidence for a cooperativity mechanism in the chaperone’s catalytic cycle. Single-molecule PET fluorescence microscopy opens up avenues in the multi-dimensional exploration of protein dynamics and allosteric mechanisms.
KW  - chaperones
KW  - fluorescence spectroscopy
KW  - molecular conformation
KW  - single-molecule biophysics
KW  - total internal reflection microscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-265754
VL  - 12
ER  - 
TY  - JOUR
A1  - Rat, Charlotte
A1  - Heiby, Julia C.
A1  - Bunz, Jessica P.
A1  - Neuweiler, Hannes
T1  - Two-step self-assembly of a spider silk molecular clamp
JF  - Nature Communications
N2  - Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk.
KW  - Circular dichroism
KW  - Fluorescence spectroscopy
KW  - Biokinetics
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225016
VL  - 9
ER  - 
TY  - JOUR
A1  - Lichter, Katharina
A1  - Paul, Mila Marie
A1  - Pauli, Martin
A1  - Schoch, Susanne
A1  - Kollmannsberger, Philip
A1  - Stigloher, Christian
A1  - Heckmann, Manfred
A1  - Sirén, Anna-Leena
T1  - Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse
JF  - Cell Reports
N2  - Rab3A-interacting molecule (RIM) is crucial for fast Ca\(^{2+}\)-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α\(^{−/−}\) and wild-type mice. In RIM1α\(^{−/−}\), AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0–2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α\(^{−/−}\) is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.
KW  - active zone
KW  - acute brain slices
KW  - CA3
KW  - electron tomography
KW  - high-pressure freezing
KW  - hippocampal mossy fiber bouton
KW  - RIM1α
KW  - SV pool
KW  - synaptic ultrastructure
KW  - presynaptic
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300913
VL  - 40
IS  - 12
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Hansmann, Paul
A1  - Falk, Heinz
A1  - Sitte, Peter
T1  - Ultrastructural localization of DNA in two Cryptomonas species by use of a monoclonal DNA-antibody
N2  - Immunogold cytochemistry - DNA localization - Cryptomonas nucleomorph The distribution and subcellular localization of DNA in the unicellular alga Cryptomonas has been investigated electron-microscopically by indirect immunocytochemistry, using a monoclonal DNA antibody and a gold-Iabeled secondary antibody. This technique proved to be very sensitive and entirely specific. DNA could be demonstrated in four different compartments (nucleus, nucleomorph, plastid, and mitochondrion). Within the plastid, DNA is concentrated in stroma regions that are localized preferentially around the center of the organelle. The mitochondrion contains several isolated DNA-containing regions (nucleoids). Within the nucleus, most of the DNA is localized in the 'condensed' chromatin. DNA was also detectable in small areas of the nucleolus, whereas the interchromatin space of the nucleus appeared almost devoid of DNA. Within the nucleomorph, DNA is distributed inhomogeneously in the matrix. DNA could furthermore be detected in restricted areas of the 'fibrillogranular body' of the nucleomorph, resembling the situation encountered in the nucleol us. The presence of DNA and its characteristic distribution in the nucleomorph provide additional, strong evidence in favour of the interpretation of that organelle as the residual nucleus of a eukaryotic endosymbiont in Cryptomonas.
KW  - Cytologie
Y1  - 1986
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-39746
ER  -