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Structural and Functional Insights into Bacillus subtilis Sigma Factor Inhibitor, CsfB

Research output: Contribution to journalArticle

Santiago Martínez-Lumbreras, Caterina Alfano, Nicola J. Evans, Katherine M. Collins, Kelly A. Flanagan, R. Andrew Atkinson, Ewelina M. Krysztofinska, Anupama Vydyanath, Jacquelin Jackter, Sarah Fixon-Owoo, Amy H. Camp, Rivka L. Isaacson

Original languageEnglish
Early online date8 Mar 2018
StateE-pub ahead of print - 8 Mar 2018

King's Authors


Global changes in bacterial gene expression can be orchestrated by the coordinated activation/deactivation of alternative sigma (σ) factor subunits of RNA polymerase. Sigma factors themselves are regulated in myriad ways, including via anti-sigma factors. Here, we have determined the solution structure of anti-sigma factor CsfB, responsible for inhibition of two alternative sigma factors, σG and σE, during spore formation by Bacillus subtilis. CsfB assembles into a symmetrical homodimer, with each monomer bound to a single Zn2+ ion via a treble-clef zinc finger fold. Directed mutagenesis indicates that dimer formation is critical for CsfB-mediated inhibition of both σG and σE, and we have characterized these interactions in vitro. This work represents an advance in our understanding of how CsfB mediates inhibition of two alternative sigma factors to drive developmental gene expression in a bacterium. Martínez-Lumbreras, Alfano et al. have solved the structure of the anti-sigma factor CsfB and explored its role in inhibiting two alternative sigma factors during Bacillus subtilis spore formation. The results provide insight into the molecular mechanism underlying a gene expression switch in bacteria.

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