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The Bacillus subtilis Competence Transcription Factor, ComK, Overrides LexA-imposed Transcriptional Inhibition without Physically Displacing LexA

Lookup NU author(s): Dr Leendert Hamoen

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Abstract

During the development of competence inBacillus subtilis the recA gene is activated by the competence transcription factor, ComK, which is presumably required to alleviate the transcriptional repression of recA by LexA. To investigate the mechanism by which ComK activatesrecA transcription we examined the binding of ComK and LexA to the recA promoter in vitro. Using hydroxyl radical protection analyses to establish the location of ComK dimer-binding sites within the recA promoter, we identified four AT-boxes in a configuration unique for ComK-regulated promoters. Gel mobility shift experiments showed that all four ComK dimer-binding sites were occupied at ComK concentrations in the physiological range. In addition, occupation of all ComK-binding sites did not prevent LexA from binding to the recA promoter, despite the fact that the ComK and LexA recognition motifs partially overlap. Although ComK did not replace LexA from the recA promoter, in vitro transcription analyses indicated that the presence of ComK is sufficient to alleviate LexA repression ofrecA.

Publication metadata

Author(s): Hamoen LW, Haijema B, Bijlsma JJ, Venema G, Lovett CM

Publication type: Article

Publication status: Published

Journal: The Journal of Biological Chemistry

Year: 2001

Volume: 276

Issue: 46

Pages: 42901-42907

ISSN (print): 0021-9258

Publisher: American Society for Biochemistry and Molecular Biology

URL: http://dx.doi.org/10.1074/jbc.M104407200

DOI: 10.1074/jbc.M104407200

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