bkd gene cluster is regulated by BkdR and CcpA in Bacillus thuringiensis

Abstract:

[Objective] We analyzed the transcriptional regulation of bkd gene cluster by BkdR and CcpA in Bacillus thuringiensis (Bt), which is involved in leucine, isoleucine and valine metabolism. To determine the mechanism of transcriptional regulation of bkd gene cluster.[Methods] Induced transcriptional activity of bkd promoter (Pptb) was analyzed by promoter fusions with lacZ gene. ccpA insertion mutant was constructed by homologous recombination. Purification of BkdR and CcpA was using HiTrap chelating column. The binding of bkd promoter with CcpA protein was verified by electrophoresis mobility shift assays.[Results] Transcriptional activity of Pptb was induced by leucine, isoleucine, and valine. The induced transcriptional activity of Pptb was sharply decreased in bkdR mutant, but increased in ccpA mutant. Pptb could bind to the BkdR and CcpA protein, respectively.[Conclusion] The induced transcription of bkd gene cluster is positively regulated by BkdR and negatively regulated by CcpA.