title: Phosphotransferase system-dependent extracellular growth of listeria monocytogenes is regulated by alternative sigma factors σL and σH.
abstract: Alternative sigma (σ) factors and phosphotransferase systems (PTSs) play pivotal roles in the environmental adaptation and virulence of Listeria monocytogenes. The growth of the L. monocytogenes parent strain 10403S and 15 isogenic alternative σ factor mutants was assessed in defined minimal medium (DM) with PTS-dependent or non-PTS-dependent carbon sources at 25°C or 37°C. Overall, our results suggested that the regulatory effect of alternative σ factors on the growth of L. monocytogenes is dependent on the temperature and the carbon source. One-way analysis of variance (one-way ANOVA) showed that the factor "strain" had a significant effect on the maximum growth rate (μmax), lag phase duration (λ), and maximum optical density (ODmax) in PTS-dependent carbon sources (P < 0.05) but not in a non-PTS-dependent carbon source. Also, the ODmax was not affected by strain for any of the three PTS-dependent carbon sources at 25°C but was affected by strain at 37°C. Monitoring by quantitative real-time PCR (qRT-PCR) showed that transcript levels for lmo0027, a glucose-glucoside PTS permease (PTS(Glc)-1)-encoding gene, were higher in the absence of σ(L), and lower in the absence of σ(H), than in the parent strain. Our data thus indicate that σ(L) negatively regulates lmo0027 and that the increased μmax observed for the ΔsigL strain in DM with glucose may be associated with increased expression of PTS(Glc)-1 encoded by lmo0027. Our findings suggest that σ(H) and σ(L) mediate the PTS-dependent growth of L. monocytogenes through complex transcriptional regulations and fine-tuning of the expression of specific pts genes, including lmo0027. Our findings also reveal a more important and complex role of alternative σ factors in the regulation of growth in different sugar sources than previously assumed.
authors.affiliation: Food, Nutrition and Health, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA siyun.wang@ubc.ca.
authors.forename: Siyun
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
authors.forename: Renato H
authors.initials: RH
authors.lastname: Orsi
authors.affiliation: Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
authors.forename: Silin
authors.initials: S
authors.lastname: Tang
authors.affiliation: Institute for Food Safety and Health, Illinois Institute of Technology, Bedford Park, Illinois, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Wiedmann
authors.affiliation: Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Boor
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D008089:Listeria monocytogenes / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D010770:Phosphotransferases / Q000235:genetics* / Q000378:metabolism*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor; D010770:Phosphotransferases