This proposal investigates cell envelope stress responses in Bacillus subtilis, a model organism for the Gram positive bacteria. Antibiotics and other agents that impair the synthesis or function of the cell membrane or peptidoglycan cell wall are of critical importance in clinical medicine. Exposure to sub-lethal levels of these antibiotics activates the transcription of large sets of genes. These cell envelope stress responses are frequently adaptive and include mechanisms that protect the organism against the antibiotics. In Bacillus subtilis, these stress responses are coordinated by several of the seven alternative sigma subunits for RNA polymerase of the extracytoplasmic function (ECF) subfamily. This proposal is focused on defining the role of ECF sigma factors in regulating gene expression and identifying pathways of adaptation and resistance to antibiotics. Using a combination of classical and molecular genetics, genomics, transcriptomics, and biochemical approaches, these studies will define the pathways that activate expression of the various ECF sigma factor regulons, identify genes and functions controlled by ECF sigma factors, and investigate novel pathways of antibiotic resistance.
The bacterial envelope, comprising a lipid membrane and a peptidoglycan cell wall, separates the cell from the environment and is a target for the majority of antibiotics currently in clinical use. This proposal studies how bacteria respond to antibiotics that block the synthesis or function of the cell envelope and addresses the mechanisms by which bacteria become resistant to antibiotics. This proposal focuses specifically on the model Gram positive bacterium Bacillus subtilis which is related to Staphylococcus aureus and pathogenic streptococcal and enterococcal strains.
|Zhao, Heng; Sun, Yingjie; Peters, Jason M et al. (2016) Depletion of Undecaprenyl Pyrophosphate Phosphatases Disrupts Cell Envelope Biogenesis in Bacillus subtilis. J Bacteriol 198:2925-2935|
|Helmann, John D (2016) Bacillus subtilis extracytoplasmic function (ECF) sigma factors and defense of the cell envelope. Curr Opin Microbiol 30:122-32|
|Helmann, John D (2015) Molecular scribes in the spotlight: Methods for illuminating Bacterial and Archaeal transcription. Methods 86:1-3|
|Schirner, Kathrin; Eun, Ye-Jin; Dion, Mike et al. (2015) Lipid-linked cell wall precursors regulate membrane association of bacterial actin MreB. Nat Chem Biol 11:38-45|
|Helmann, John D (2015) Chemical proteomics reveals a second family of cyclic-di-AMP hydrolases. Proc Natl Acad Sci U S A 112:1921-2|
|Gaballa, Ahmed; Chi, Bui Khanh; Roberts, Alexandra A et al. (2014) Redox regulation in Bacillus subtilis: The bacilliredoxins BrxA(YphP) and BrxB(YqiW) function in de-bacillithiolation of S-bacillithiolated OhrR and MetE. Antioxid Redox Signal 21:357-67|
|Lee, Yong Heon; Helmann, John D (2014) Mutations in the primary sigma factor ÏƒA and termination factor rho that reduce susceptibility to cell wall antibiotics. J Bacteriol 196:3700-11|
|Kingston, Anthony W; Zhao, Heng; Cook, Gregory M et al. (2014) Accumulation of heptaprenyl diphosphate sensitizes Bacillus subtilis to bacitracin: implications for the mechanism of resistance mediated by the BceAB transporter. Mol Microbiol 93:37-49|
|Kashyap, Des Raj; Rompca, Annemarie; Gaballa, Ahmed et al. (2014) Peptidoglycan recognition proteins kill bacteria by inducing oxidative, thiol, and metal stress. PLoS Pathog 10:e1004280|
|Wright, Gerard D; Hung, Deborah T; Helmann, John D (2013) How antibiotics kill bacteria: new models needed? Nat Med 19:544-5|
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