Transcriptional regulation and mechanism of sigN (ZpdN), a pBS32-encoded sigma factor in bacillus subtilis
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mBio-2019-Burton-e01899-19.full.pdf
Description
Published version
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939.65 KB
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Adobe PDF
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Author(s)
DeLoughery, Aaron
Li, Gene-Wei
Date Issued
September 2019
Journal
MBio
Publisher
American Society for Microbiology
Citation
Burton, Aisha T. et al. “Transcriptional regulation and mechanism of sigN (ZpdN), a pBS32-encoded sigma factor in bacillus subtilis.” MBio 10 (2019): e01899-19 © 2019 The Author(s)
Version
Final published version
Abstract
Laboratory strains of Bacillus subtilis encode many alternative sigma factors, each dedicated to expressing a unique regulon such as those involved in stress resistance, sporulation, and motility. The ancestral strain of B. subtilis also encodes an additional sigma factor homolog, ZpdN, not found in lab strains due to being encoded on the large, low-copy-number plasmid pBS32, which was lost during domestication. DNA damage triggers pBS32 hyperreplication and cell death in a manner that depends on ZpdN, but how ZpdN mediates these effects is unknown. Here, we show that ZpdN is a bona fide sigma factor that can direct RNA polymerase to transcribe ZpdN-dependent genes, and we rename ZpdN SigN accordingly. Rend-seq (end-enriched transcriptome sequencing) analysis was used to determine the SigN regulon on pBS32, and the 5= ends of transcripts were used to predict the SigN consensus sequence. Finally, we characterize the regulation of SigN itself and show that it is transcribed by at least three promoters: PsigN1, a strong SigA-dependent LexArepressed promoter; PsigN2, a weak SigA-dependent constitutive promoter; and PsigN3, a SigN-dependent promoter. Thus, in response to DNA damage SigN is derepressed and then experiences positive feedback. How cells die in a pBS32-dependent manner remains unknown, but we predict that death is the product of expressing one or more genes in the SigN regulon. IMPORTANCE Sigma factors are utilized by bacteria to control and regulate gene expression. Some sigma factors are activated during times of stress to ensure the survival of the bacterium. Here, we report the presence of a sigma factor that is encoded on a plasmid that leads to cellular death after DNA damage.
MIT Department
Massachusetts Institute of Technology. Department of Biology
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1128/mBio.01899-19
