Rok (YkuW) regulates genetic competence in Bacillus subtilis by directly repressing comK.
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 indivi-dually 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.
Hoa
Tran Thu
TT
Public Health Research Institute, 455 First Avenue, New York, NY 10016, USA.
Tortosa
Pablo
P
Albano
Mark
M
Dubnau
David
D
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D007763:Lac Operon; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics*
D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C087449:comK protein, Bacillus subtilis