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CsrA ofBacillus subtilisregulates translation initiation of the gene encoding the flagellin protein (hag) by blocking ribosome binding
- Source :
- Molecular Microbiology. 64:1605-1620
- Publication Year :
- 2007
- Publisher :
- Wiley, 2007.
-
Abstract
- The global regulatory Csr (carbon storage regulator) and the homologous Rsm (repressor of secondary metabolites) systems of Gram-negative bacteria typically consist of an RNA-binding protein (CsrA/RsmA) and at least one sRNA that functions as a CsrA antagonist. CsrA modulates gene expression post-transcriptionally by regulating translation initiation and/or mRNA stability of target transcripts. While Csr has been extensively studied in Gram-negative bacteria, until now Csr has not been characterized in any Gram-positive organism. csrA of Bacillus subtilis is the last gene of a flagellum biosynthetic operon. In addition to the previously identified sigma(D)-dependent promoter that controls expression of the entire operon, a sigma(A)-dependent promoter was identified that temporally controls expression of the last two genes of the operon (fliW-csrA); expression peaks 1 h after cell growth deviates from exponential phase. hag, the gene encoding flagellin, was identified as a CsrA-regulated gene. CsrA was found to repress hag'-'lacZ expression, while overexpression of csrA reduces cell motility. In vitro binding studies identified two CsrA binding sites in the hag leader transcript, one of which overlaps the hag Shine-Dalgarno sequence. Toeprint and cell-free translation studies demonstrate that bound CsrA prevents ribosome binding to the hag transcript, thereby inhibiting translation initiation and Hag synthesis.
Details
- ISSN :
- 0950382X
- Volume :
- 64
- Database :
- OpenAIRE
- Journal :
- Molecular Microbiology
- Accession number :
- edsair.doi...........bf156e926b629326dfa3d443803d993e