Department of molecular bacteriology (MOBA)
http://hdl.handle.net/10033/620636
2024-03-29T10:59:06ZCritical Role of Zur and SmtB in Zinc Homeostasis of Mycobacterium smegmatis.
http://hdl.handle.net/10033/623230
Critical Role of Zur and SmtB in Zinc Homeostasis of Mycobacterium smegmatis.
Goethe, Elke; Laarmann, Kristin; Lührs, Janita; Jarek, Michael; Meens, Jochen; Lewin, Astrid; Goethe, Ralph
Zinc homeostasis is crucial for bacterial cells, since imbalances affect viability. However, in mycobacteria, knowledge of zinc metabolism is incomplete. Mycobacterium smegmatis (MSMEG) is an environmental, nonpathogenic Mycobacterium that is widely used as a model organism to study mycobacterial metabolism and pathogenicity. How MSMEG maintains zinc homeostasis is largely unknown. SmtB and Zur are important regulators of bacterial zinc metabolism. In mycobacteria, these regulators are encoded by an operon, whereas in other bacterial species, SmtB and Zur are encoded on separate loci. Here, we show that the smtB-zur operon is consistently present within the genus Mycobacterium but otherwise found only in Nocardia, Saccharothrix, and Corynebacterium diphtheriae By RNA deep sequencing, we determined the Zur and SmtB regulons of MSMEG and compared them with transcriptional responses after zinc starvation or excess. We found an exceptional genomic clustering of genes whose expression was strongly induced by zur deletion and zinc starvation. These genes encoded zinc importers such as ZnuABC and three additional putative zinc transporters, including the porin MspD, as well as alternative ribosomal proteins. In contrast, only a few genes were affected by deletion of smtB and zinc excess. The zinc exporter ZitA was most prominently regulated by SmtB. Moreover, transcriptional analyses in combination with promoter and chromatin immunoprecipitation assays revealed a special regulation of the smtB-zur operon itself: an apparently zinc-independent, constitutive expression of smtB-zur resulted from sensitive coregulation by both SmtB and Zur. Overall, our data revealed yet unknown peculiarities of mycobacterial zinc homeostasis.IMPORTANCE Zinc is crucial for many biological processes, as it is an essential cofactor of enzymes and a structural component of regulatory and DNA binding proteins. Hence, all living cells require zinc to maintain constant intracellular levels. However, in excess, zinc is toxic. Therefore, cellular zinc homeostasis needs to be tightly controlled. In bacteria, this is achieved by transcriptional regulators whose activity is mediated via zinc-dependent conformational changes promoting or preventing their binding to DNA. SmtB and Zur are important antagonistically acting bacterial regulators in mycobacteria. They sense changes in zinc concentrations in the femtomolar range and regulate transcription of genes for zinc acquisition, storage, and export. Here, we analyzed the role of SmtB and Zur in zinc homeostasis in Mycobacterium smegmatis Our results revealed novel insights into the transcriptional processes of zinc homeostasis in mycobacteria and their regulation.
2020-04-21T00:00:00ZPredicting antimicrobial resistance in Pseudomonas aeruginosa with machine learning‐enabled molecular diagnostics
http://hdl.handle.net/10033/623211
Predicting antimicrobial resistance in Pseudomonas aeruginosa with machine learning‐enabled molecular diagnostics
Khaledi, Ariane; Weimann, Aaron; Schniederjans, Monika; Asgari, Ehsaneddin; Kuo, Tzu‐Hao; Oliver, Antonio; Cabot, Gabriel; Kola, Axel; Gastmeier, Petra; Hogardt, Michael; Jonas, Daniel; Mofrad, Mohammad RK; Bremges, Andreas; McHardy, Alice C; Häussler, Susanne
Limited therapy options due to antibiotic resistance underscore
the need for optimization of current diagnostics. In some bacterial
species, antimicrobial resistance can be unambiguously predicted
based on their genome sequence. In this study, we sequenced the
genomes and transcriptomes of 414 drug-resistant clinical Pseudomonas
aeruginosa isolates. By training machine learning classifiers
on information about the presence or absence of genes, their
sequence variation, and expression profiles, we generated predictive
models and identified biomarkers of resistance to four
commonly administered antimicrobial drugs. Using these data
types alone or in combination resulted in high (0.8–0.9) or very
high (> 0.9) sensitivity and predictive values. For all drugs except
for ciprofloxacin, gene expression information improved diagnostic
performance. Our results pave the way for the development of a
molecular resistance profiling tool that reliably predicts antimicrobial
susceptibility based on genomic and transcriptomic markers.
The implementation of a molecular susceptibility test system in
routine microbiology diagnostics holds promise to provide earlier
and more detailed information on antibiotic resistance profiles of
bacterial pathogens and thus could change how physicians treat
bacterial infections.
2020-02-12T00:00:00ZFibrosis and Immune Cell Infiltration Are Separate Events Regulated by Cell-Specific Receptor Notch3 Expression.
http://hdl.handle.net/10033/623201
Fibrosis and Immune Cell Infiltration Are Separate Events Regulated by Cell-Specific Receptor Notch3 Expression.
Brandt, Sabine; Ballhause, Tobias M; Bernhardt, Anja; Becker, Annika; Salaru, Delia; Le-Deffge, Hien Minh; Fehr, Alexander; Fu, Yan; Philipsen, Lars; Djudjaj, Sonja; Müller, Andreas J; Kramann, Rafael; Ibrahim, Mahmoud; Geffers, Robert; Siebel, Chris; Isermann, Berend; Heidel, Florian H; Lindquist, Jonathan A; Mertens, Peter R
Kidney injuries that result in chronic inflammation initiate crosstalk between stressed resident cells and infiltrating immune cells. In animal models, whole-body receptor Notch3 deficiency protects from leukocyte infiltration and organ fibrosis. However, the relative contribution of Notch3 expression in tissue versus infiltrating immune cells is unknown.
2020-08-28T00:00:00ZNon-Typeable Invade Choroid Plexus Epithelial Cells in a Polar Fashion.
http://hdl.handle.net/10033/623198
Non-Typeable Invade Choroid Plexus Epithelial Cells in a Polar Fashion.
Wegele, Christian; Stump-Guthier, Carolin; Moroniak, Selina; Weiss, Christel; Rohde, Manfred; Ishikawa, Hiroshi; Schroten, Horst; Schwerk, Christian; Karremann, Michael; Borkowski, Julia
Non-typeable Haemophilus influenzae (NTHI) is a pathogen of the human respiratory tract causing the majority of invasive H. influenzae infections. Severe invasive infections such as septicemia and meningitis occur rarely, but the lack of a protecting vaccine and the increasing antibiotic resistance of NTHI impede treatment and emphasize its relevance as a potential meningitis causing pathogen. Meningitis results from pathogens crossing blood-brain barriers and invading the immune privileged central nervous system (CNS). In this study, we addressed the potential of NTHI to enter the brain by invading cells of the choroid plexus (CP) prior to meningeal inflammation to enlighten NTHI pathophysiological mechanisms. A cell culture model of human CP epithelial cells, which form the blood-cerebrospinal fluid barrier (BCSFB) in vivo, was used to analyze adhesion and invasion by immunofluorescence and electron microscopy. NTHI invade CP cells in vitro in a polar fashion from the blood-facing side. Furthermore, NTHI invasion rates are increased compared to encapsulated HiB and HiF strains. Fimbriae occurrence attenuated adhesion and invasion. Thus, our findings underline the role of the BCSFB as a potential entry port for NTHI into the brain and provide strong evidence for a function of the CP during NTHI invasion into the CNS during the course of meningitis.
2020-08-10T00:00:00Z