title: Characterization of Mycobacterium smegmatis sigF mutant and its regulon: overexpression of SigF antagonist (MSMEG_1803) in M. smegmatis mimics sigF mutant phenotype, loss of pigmentation, and sensitivity to oxidative stress.
abstract: In Mycobacterium smegmatis, sigF is widely expressed during different growth stages and plays role in adaptation to stationary phase and oxidative stress. Using a sigF deletion mutant of M. smegmatis mc(2) 155, we demonstrate that SigF is not essential for growth of bacterium. Deletion of sigF results in loss of carotenoid pigmentation which rendered increased susceptibility to H2 O2 induced oxidative stress in M. smegmatis. SigF modulates the cell surface architecture and lipid biosynthesis extending the repertoire of SigF function in this species. M. smegmatis SigF regulon included variety of genes expressed during exponential and stationary phases of growth and those responsible for oxidative stress, lipid biosynthesis, energy, and central intermediary metabolism. Furthermore, we report the identification of a SigF antagonist, an anti-sigma factor (RsbW), which upon overexpression in M. smegmatis wild type strain produced a phenotype similar to M. smegmatis mc(2) 155 ΔsigF strain. The SigF-anti-SigF interaction is duly validated using bacterial two-hybrid and pull down assays. In addition, anti-sigma factor antagonists, RsfA and RsfB were identified and their interactions with anti-sigma factor were experimentally validated. Identification of these proteins will help decode regulatory circuit of this alternate sigma factor.
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Anirudh K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Debashis
authors.initials: D
authors.lastname: Dutta
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Singh
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Vishal
authors.initials: V
authors.lastname: Srivastava
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Biswas
authors.affiliation: Division of Microbiology, CSIR-Central Drug Research Institute, Lucknow, 226031, India.
authors.forename: Bhupendra N
authors.initials: BN
authors.lastname: Singh
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002338:Carotenoids / Q000096:biosynthesis*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D010641:Phenotype; D018085:Regulon; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C080358:RsbW protein, bacteria; D012808:Sigma Factor; D002338:Carotenoids
keywords: Anti-SigF; M. smegmatis; SigF regulon; anti-SigF antagonists; oxidative stress