Regulation of CRISPR-Associated Genes by Rv1776c (CasR) in Mycobacterium tuberculosis .

The CRISPR-Cas system is an adaptive immune system for many bacteria and archaea to defend against foreign nucleic acid invasion, and this system is conserved in the genome of (). Although the CRISPR-Cas system-mediated immune defense mechanism has been revealed in , the regulation of gene expression is poorly understood. In this study, we identified a transcription factor, CasR (CRISPR-associated protein repressor, encoded by ), and it could bind to the upstream DNA sequence of the CRISPR-Cas gene cluster and regulate the expression of genes. EMSA and ChIP assays confirmed that CasR could interact with the upstream sequence of the promoter, both in vivo and in vitro. Furthermore, DNA footprinting assay revealed that CasR recognized a 20 bp palindromic sequence motif and negatively regulated the expression of In conclusion, our research elucidates the regulatory effect of CasR on the expression of CRISPR-associated genes in mycobacteria, thus providing insight into gene expression regulation of the CRISPR-Cas system.