Rok (YkuW) regulates genetic competence in Bacillus subtilis by directly repressing comK

Tran Thu Hoa, Pablo Tortosa, Mark Albano, David Dubnau

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The Rok (YkuW) protein acts as a negative regulator of comK, which encodes the competence transcription factor of Bacillus subtilis. In the absence of Rok, ComK is overproduced, and when excess Rok is present comK transcription is inhibited. Rok acts transcriptionally to repress comK expression but does not affect ComK stability, which is controlled by the MecA switch. Gel-shift assays show that Rok binds directly to a DNA fragment that contains the comK promoter. SinR and AbrB act negatively on rok transcription, and the inactivation of rok bypasses the positive requirements for sinR and abrB for the expression of comK. Therefore, the dependence of comK expression on SinR and AbrB may be a result of their repression of rok transcription. It has also been shown in vivo that Rok and ComK can individually repress rok transcription, and that Rok and ComK bind to the rok promoter in vitro. These interactions establish feedback loops, and the roles of these circuits are discussed.

Original languageEnglish (US)
Pages (from-to)15-26
Number of pages12
JournalMolecular microbiology
Issue number1
StatePublished - Mar 20 2002
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Microbiology
  • Molecular Biology

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