title: Temperature- and nitrogen source-dependent regulation of GlnR target genes in Listeria monocytogenes.
abstract: The ubiquitous pathogen Listeria monocytogenes lives either saprophytically in the environment or within cells in a vertebrate host, thus adapting its lifestyle to its ecological niche. Growth experiments at 24 and 37 °C (environmental and host temperature) with ammonium or glutamine as nitrogen sources revealed that ammonium is the preferred nitrogen source of L. monocytogenes. Reduced growth on glutamine is more obvious at 24 °C. Global transcriptional microarray analyses showed that the most striking difference in temperature-dependent transcription was observed for central nitrogen metabolism genes, glnR (glutamine synthetase repressor GlnR), glnA (glutamine synthetase GlnA), amtB (ammonium transporter AmtB), glnK (PII regulatory protein GlnK), and gdh (glutamate dehydrogenase) when cells were grown on glutamine. When grown on ammonium, both at 24 and 37 °C, the transcriptional level of these genes resembles that of cells grown with glutamine at 37 °C. Electrophoretic mobility shift assay studies and qPCR analyses in the wild-type L. monocytogenes and the deletion mutant L. monocytogenes ∆glnR revealed that the transcriptional regulator GlnR is directly involved in temperature- and nitrogen source-dependent regulation of the respective genes. Glutamine, a metabolite known to influence GlnR activity, seems unlikely to be the (sole) intracellular signal mediating this temperature-and nitrogen source-dependent metabolic adaptation.
authors.affiliation: Lehrstuhl für Mikrobielle Ökologie, Technische Universität München, Wissenschaftszentrum Weihenstephan, Freising, Germany; Abteilung Mikrobiologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Technische Universität München, Freising, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Kaspar
authors.forename: Franziska
authors.initials: F
authors.lastname: Auer
authors.forename: Jakob
authors.initials: J
authors.lastname: Schardt
authors.forename: Franziska
authors.initials: F
authors.lastname: Schindele
authors.forename: Alberto
authors.initials: A
authors.lastname: Ospina
authors.forename: Claudia
authors.initials: C
authors.lastname: Held
authors.forename: Armin
authors.initials: A
authors.lastname: Ehrenreich
authors.forename: Siegfried
authors.initials: S
authors.lastname: Scherer
authors.forename: Stefanie
authors.initials: S
authors.lastname: Müller-Herbst
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics* / Q000254:growth & development; D009584:Nitrogen / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D009584:Nitrogen
keywords: GlnR; Listeria monocytogenes; ammonium; glutamine; nitrogen metabolism; temperature