@phdthesis{Hartmann2010,
  author    = {Hartmann, Thomas},
  title     = {Nitrogen metabolism in Aspergillus fumigatus with emphasis on the oligopeptide transporter (OPT) gene family},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-54027},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {The saprophytic filamentous fungus Aspergillus fumigatus has been gaining importance as an opportunistic human pathogen over the past decades. Advances in modern medicine have created a growing group of patients susceptible to infection with A. fumigatus, often contracting potentially deadly invasive aspergillosis. The virulence of this pathogen appears to be a multifactorial trait, a combination of physiological characteristics that enables the fungus to infect immunocompromised humans. This work concentrates on the nitrogen metabolism of A. fumigatus, which is essential for meeting the nutritional needs inside the human host. Using DNA microarrays, the transcriptional response during growth on three different secondary nitrogen sources was examined, which revealed the metabolic versatility of A. fumigatus, especially when challenged with proteins as the sole source of nitrogen. In-depth transcriptional profiling of the eight-member oligopeptide transporter (OPT) gene family underlined the importance of oligopeptide transport for growth on complex nitrogen sources like BSA or collagen. Heterologous expression of the opt genes in Saccharomyces cerevisiae showed their functionality as oligopeptide transporters, and characterized their substrate specificity. Using a Cre/loxP based genetic tool, a complete deletion of all opt genes in A. fumigatus was achieved. The resultant strain exhibited diminished growth on medium where the oligopeptide GPGG was the sole nitrogen source, but did not show any other in vitro phenotype. The opt deletion strain was not attenuated in virulence in a murine model of pulmonary aspergillosis, suggesting that the OPT gene family is not necessary for successful infection. The connection of oligopeptide transport and extracellular proteolytic activity was investigated by deleting the genes encoding Dpp4 and Dpp5, two dipeptidyl peptidases, or PrtT, the transcriptional regulator of major secreted proteases, in the complete opt deletion background. In contrast to the deletion of dpp4 and dpp5, which did not result in any additional phenotype, the absence of prtT led to a drastic growth defect on porcine lung agar. This suggests a synergistic action of extracellular proteolytic digest of proteins and transport of oligopeptide degradation products into the cell. Finally, this work established the bacterial β-Rec/six site-specific recombination system as a novel genetic tool for targeted gene deletion in A. fumigatus.},
  subject      = {Aspergillus fumigatus},
  language  = {en}
}
@phdthesis{Schielke2010,
  author    = {Schielke, Stephanie},
  title     = {Functional and molecular characterization of FarR - a transcriptional regulator of the MarR family in Neisseria meningitidis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48550},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Neisseria meningitidis is a facultatively pathogenic human commensal and strictly adapted to its niche within the human host, the nasopharynx. Not much is known about the regulatory processes required for adaptation to this environment. Therefore the role of the transcriptional regulator NMB1843, one of the two predicted regulators of the MarR family in the meningococcal genome, was investigated. As this gene displayed a high sequence homology to FarR, the Fatty acid resistance Regulator in N. gonorrhoeae, we designated the meningococcal protein FarR (NmFarR). Homology modeling of this protein revealed a dimeric structure with the characteristic winged helix-turn-helix DNA binding motif of the MarR family. NmFarR is highly conserved among meningococcal strains and expression of farR during exponential growth is controlled post-transcriptionally, being highest in the late exponential phase. By means of electrophoretic mobility shift assays (EMSAs) the direct and specific binding of FarR to the farAB promoter region was shown, comparable to its homologue in gonococci. As FarR is involved in fatty acid resistance in N. gonorrhoeae, susceptibility assays with the medium chain lauric acid (C12:0), the long chain saturated palmitic acid (C16:0) and the long chain unsaturated linoleic acid (C18:2) were performed, testing a wide variety of strains of both species. In contrast to the unusually susceptible gonococci, a high intrinsic fatty acid resistance was detected in almost all meningococcal isolates. The molecular basis for this intrinsic resistance in N. meningitidis was elucidated, showing that both a functional FarAB efflux pump system as well as an intact lipopolysaccharide (LPS) are responsible for palmitic acid resistance. However, even despite circumvention of the intrinsic resistance, FarR could not be connected with fatty acid resistance in meningococci. Instead, FarR was shown to directly and specifically repress expression of the Neisseria adhesin A (nadA), a promising vaccine candidate absent in N. gonorrhoeae. Microarray analyses verified these results and disclosed no further similarly regulated genes, rendering the FarR regulon the smallest regulon in meningococci reported until now. The exact FarR binding site within the nadA promoter region was identified as a 16 bp palindromic repeat and its influence on nadA transcription was proved by reporter gene fusion assays. This repression was also shown to be relevant for infection as farR deficient mutant strains displayed an increased attachment to epithelial cells. Furthermore, farR transcription was attested to be repressed upon contact with active complement components within human serum. Concluding, it is shown that FarR adopted a role in meningococcal host niche adaptation, holding the balance between immune evasion by repressing the highly antigenic nadA and host cell attachment via this same adhesin.},
  subject      = {Transkription <Genetik>},
  language  = {en}
}
@phdthesis{Schammann2010,
  author    = {Schammann, Markus},
  title     = {Die Isoformen der Airway Trypsin-like Protease bei Mensch, Maus und Ratte. Charakterisierung einer neuen Proteasen-Familie und ihre Rolle in der humanen Nebennierentumorgenese},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-53733},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Ausgehend von der bereits bekannten AsP (Adrenal secretory Protease; RAT2) der Ratte, wurde in dieser Arbeit die neue Familie der „Airway Trypsin-like Serinproteasen" mit ihren Isoformen bei Mensch, Maus und Ratte (HAT, MAT und RAT) untersucht. Die codierenden Gene wurden identifiziert. Bei Maus und Ratte existieren zwei Isoformen, eine kurze und eine lange, die das Ergebnis von alternativer Transkription sind. Beim Menschen konnte ein Stopcodon nachgewiesen werden, welches die Bildung einer kurzen Isoform verhindert. Ferner wurden der Aufbau, die Strukturdom{\"a}nen und die Gewebeverteilung der Isoformen charakterisiert. Die Ergebnisse deuten auf ein multifunktionelles Protein hin, welches in viele physiologische Prozesse involviert sein d{\"u}rfte. Die Rolle von AsP sollte {\"u}ber die Steuerung der adrenalen Mitogenese hinausreichen. Die weitverbreitete Expression der ATs in vielen Geweben stellt ihre spezifische Rolle f{\"u}r eine ausschließliche N-POMC-Spaltung und die Bildung von adrenalen Mitogenen in Frage, denn diese Spaltung f{\"a}nde an vielen verschiedenen Stellen statt, welche erkennbar in keiner Beziehung zur Nebennieren-Physiologie stehen. Ein wesentlicher Befund dieser Arbeit ist die Tatsache, dass sich die Ergebnisse bei der Ratte und der dortigen physiologischen Funktion der AsP/ RAT2 in der adrenalen Mitogenese nicht auf den Menschen {\"u}bertragen lassen. Beim Menschen l{\"a}sst sich HAT nicht in der Nebennierenrinde nachweisen, HAT stellt also nicht das humane Gegenst{\"u}ck zur AsP der Ratte dar. Umgekehrt finden sich auch bei den Nagern die langen, HAT-{\"a}hnlichen Isoformen nicht in der Nebenniere. Ferner konnte eine Beteiligung von HAT an der Nebennierentumorgenese anhand der vorliegenden Daten nicht best{\"a}tigt werden. HAT ließ sich in Nebennierenrinden-Tumoren praktisch nicht nachweisen. In Ph{\"a}ochromozytomen fand sich in 4 von 5 Gewebeproben eine HAT-Expression. Die chromaffinen Zellen im Nebennierenmark exprimieren u.a. POMC, so dass HAT hier evtl. doch eine physiologische Rolle einnehmen k{\"o}nnte. {\"U}ber die Funktion der AT-Proteasen an anderen Orten ist bislang nur wenig bekannt, hier sind weitere Untersuchungen notwendig. Zusammenfassend gelang in dieser Arbeit die Charakterisierung einer interessanten, in mehreren Spezies konservierten Proteasenfamilie, die {\"u}ber ein komplexes Expressionsmuster verf{\"u}gt. Im Gegensatz zum Menschen existieren in den Nagern zwei Isoformen, eine kurze und eine lange. Sie gehen durch den Mechanismus der alternativen Transkription aus einem einzigen Gen hervor. Aufgrund der breiten Expression in vielen Geweben d{\"u}rfte die Funktion sehr vielschichtig sein. Eine Rolle in der humanen Nebennierentumorgenese konnte f{\"u}r das humane Homolog nicht nachgewiesen werden.},
  subject      = {Serinproteinasen},
  language  = {de}
}