Open AccessCharacterization 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
Author(s) -
Singh Anirudh K.,
Dutta Debashis,
Singh Vandana,
Srivastava Vishal,
Biswas Rajesh K.,
Singh Bhupendra N.
Publication year - 2015
Publication title -
microbiologyopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.881
H-Index - 36
ISSN - 2045-8827
DOI - 10.1002/mbo3.288
Subject(s) - mycobacterium smegmatis , sigma factor , regulon , mutant , biology , biochemistry , chemistry , microbiology and biotechnology , gene , escherichia coli , rna polymerase , mycobacterium tuberculosis , medicine , tuberculosis , pathology
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 H 2 O 2 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 Δ sigF 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.