Publications from Division of Molekulare Struktur Biologie (MOSB)http://hdl.handle.net/10033/68332024-03-29T11:14:10Z2024-03-29T11:14:10ZTranscriptional and mutational profiling of an aminoglycoside resistant Pseudomonas aeruginosa small colony variant.Schniederjans, MonikaKoska, MichalHäussler, Susannehttp://hdl.handle.net/10033/6211142019-08-30T11:37:24Z2017-09-05T00:00:00ZTranscriptional and mutational profiling of an aminoglycoside resistant Pseudomonas aeruginosa small colony variant.
Schniederjans, Monika; Koska, Michal; Häussler, Susanne
Pseudomonas aeruginosa is a major causative agent of both acute and chronic infections. Although aminoglycoside antibiotics are very potent drugs to fight such infections, antibiotic failure is steadily increasing mainly due to increasing resistance of the bacteria. Many molecular mechanisms that determine resistance such as acquisition of genes encoding for aminoglycoside-inactivating enzymes or overexpression of efflux pumps have been elucidated. However, there are additional, less-well described mechanisms of aminoglycoside resistance. In this study we have profiled a clinical tobramycin resistant P. aeruginosa strain that exhibited a small colony variant (SCV) phenotype. Both, the resistance and the colony morphology phenotypes were lost upon passaging the isolate under rich medium conditions. Transcriptional and mutational profiling revealed that the SCV harbored activating mutations in the two two-component systems AmgRS and PmrAB. Introduction of these mutations singularly into the type strain PA14 conferred tobramycin and colistin resistance, respectively. However, their combined introduction had an additive effect on the tobramycin resistance phenotype. Activation of the AmgRS system slightly reduced the colony size of the PA14 wild-type, whereas the simultaneous overexpression of gacA, the response regulator of the GacSA two component system, further reduced colony size. In conclusion, we uncovered combinatorial influences of two-component systems on clinically relevant phenotypes, such as resistance and the expression of the SCV phenotype. Our results clearly demonstrate that combined activation of P. aeruginosa two-component systems exhibit pleiotropic effects with unforeseen consequences.
2017-09-05T00:00:00ZHuman lung tissue explants reveal novel interactions during Legionella pneumophila infections.Jäger, JensMarwitz, SebastianTiefenau, JanaRasch, JanineShevchuk, OlgaKugler, ChristianGoldmann, TorstenSteinert, Michaelhttp://hdl.handle.net/10033/6210492019-08-30T11:35:39Z2014-01-01T00:00:00ZHuman lung tissue explants reveal novel interactions during Legionella pneumophila infections.
Jäger, Jens; Marwitz, Sebastian; Tiefenau, Jana; Rasch, Janine; Shevchuk, Olga; Kugler, Christian; Goldmann, Torsten; Steinert, Michael
Histological and clinical investigations describe late stages of Legionnaires' disease but cannot characterize early events of human infection. Cellular or rodent infection models lack the complexity of tissue or have nonhuman backgrounds. Therefore, we developed and applied a novel model for Legionella pneumophila infection comprising living human lung tissue. We stimulated lung explants with L. pneumophila strains and outer membrane vesicles (OMVs) to analyze tissue damage, bacterial replication, and localization as well as the transcriptional response of infected tissue. Interestingly, we found that extracellular adhesion of L. pneumophila to the entire alveolar lining precedes bacterial invasion and replication in recruited macrophages. In contrast, OMVs predominantly bound to alveolar macrophages. Specific damage to septa and epithelia increased over 48 h and was stronger in wild-type-infected and OMV-treated samples than in samples infected with the replication-deficient, type IVB secretion-deficient DotA(-) strain. Transcriptome analysis of lung tissue explants revealed a differential regulation of 2,499 genes after infection. The transcriptional response included the upregulation of uteroglobin and the downregulation of the macrophage receptor with collagenous structure (MARCO). Immunohistochemistry confirmed the downregulation of MARCO at sites of pathogen-induced tissue destruction. Neither host factor has ever been described in the context of L. pneumophila infections. This work demonstrates that the tissue explant model reproduces realistic features of Legionnaires' disease and reveals new functions for bacterial OMVs during infection. Our model allows us to characterize early steps of human infection which otherwise are not feasible for investigations.
2014-01-01T00:00:00ZStructures of two bacterial resistance factors mediating tRNA-dependent aminoacylation of phosphatidylglycerol with lysine or alanine.Hebecker, StefanieKrausze, JoernHasenkampf, TatjanaSchneider, JuliaGroenewold, MaikeReichelt, JoachimJahn, DieterHeinz, Dirk WMoser, Jürgenhttp://hdl.handle.net/10033/5823392019-08-30T11:34:48Z2015-08-25T00:00:00ZStructures of two bacterial resistance factors mediating tRNA-dependent aminoacylation of phosphatidylglycerol with lysine or alanine.
Hebecker, Stefanie; Krausze, Joern; Hasenkampf, Tatjana; Schneider, Julia; Groenewold, Maike; Reichelt, Joachim; Jahn, Dieter; Heinz, Dirk W; Moser, Jürgen
The cytoplasmic membrane is probably the most important physical barrier between microbes and the surrounding habitat. Aminoacylation of the polar head group of the phospholipid phosphatidylglycerol (PG) catalyzed by Ala-tRNA(Ala)-dependent alanyl-phosphatidylglycerol synthase (A-PGS) or by Lys-tRNA(Lys)-dependent lysyl-phosphatidylglycerol synthase (L-PGS) enables bacteria to cope with cationic peptides that are harmful to the integrity of the cell membrane. Accordingly, these synthases also have been designated as multiple peptide resistance factors (MprF). They consist of a separable C-terminal catalytic domain and an N-terminal transmembrane flippase domain. Here we present the X-ray crystallographic structure of the catalytic domain of A-PGS from the opportunistic human pathogen Pseudomonas aeruginosa. In parallel, the structure of the related lysyl-phosphatidylglycerol-specific L-PGS domain from Bacillus licheniformis in complex with the substrate analog L-lysine amide is presented. Both proteins reveal a continuous tunnel that allows the hydrophobic lipid substrate PG and the polar aminoacyl-tRNA substrate to access the catalytic site from opposite directions. Substrate recognition of A-PGS versus L-PGS was investigated using misacylated tRNA variants. The structural work presented here in combination with biochemical experiments using artificial tRNA or artificial lipid substrates reveals the tRNA acceptor stem, the aminoacyl moiety, and the polar head group of PG as the main determinants for substrate recognition. A mutagenesis approach yielded the complementary amino acid determinants of tRNA interaction. These results have broad implications for the design of L-PGS and A-PGS inhibitors that could render microbial pathogens more susceptible to antimicrobial compounds.
2015-08-25T00:00:00ZMetabolic peculiarities of Aspergillus niger disclosed by comparative metabolic genomics.Sun, JibinLu, XinRinas, UrsulaZeng, An Pinghttp://hdl.handle.net/10033/5788812019-08-30T11:33:30Z2007-01-01T00:00:00ZMetabolic peculiarities of Aspergillus niger disclosed by comparative metabolic genomics.
Sun, Jibin; Lu, Xin; Rinas, Ursula; Zeng, An Ping
Aspergillus niger is an important industrial microorganism for the production of both metabolites, such as citric acid, and proteins, such as fungal enzymes or heterologous proteins. Despite its extensive industrial applications, the genetic inventory of this fungus is only partially understood. The recently released genome sequence opens a new horizon for both scientific studies and biotechnological applications.
2007-01-01T00:00:00Z