Response regulator ChiR regulates expression of chitinase gene,chiC, inStreptomyces coelicolor

Transcription from thechiC promoter, directing expression of the chitinase gene,chiC, inStreptomyces coelicolor, was analyzed usingxylE reporter gene and high-resolution S1-nuclease mapping. The transcription from thechiC promoter was induced by chitin, and this induction was dramatically reduced in theS. coelicolor chiR-disrupted strain. This indicated a dependence ofchiC expression upon thechiR gene encoding a response regulator protein. To investigate this relationship, theS. coelicolor ChiR was over-produced usingEscherichia coli T7 RNA polymerase expression system. However, gel mobility shift-assay with such a purified ChiR showed no binding in thechiC promoter region, which indicates a lack of specific phosphorylation ofE. coli overproduced ChiR that is necessary for DNA-binding activity of response regulators.