Cloning of a two-component regulatory system probably involved in the regulation of chitinase in Streptomyces coelicolor A3(2).

Using the method for the identification of promoters recognized by the sporulation specific sigma factor (sigma F), we identified a positive 950 bp Sau3AI DNA fragment in Streptomyces coelicolor A3(2). High-resolution S1-nuclease mapping identified a potential promoter, PF35, in the E. coli two-plasmid system similar to the consensus sequence of Bacillus subtilis promoters recognized by the general stress-response sigma factor (sigma B). However, the putative sigF-dependent promoter, PF35, was inactive in S. coelicolor in the course of differentiation, and it was located divergently in the promoter region directing expression of the chiC gene encoding chitinase. Sequence analysis of the region potentially governed by PF35 revealed two translationally coupled genes encoding proteins similar to bacterial two-component regulatory systems, and with the highest similarity to the two-component system chiS, chiR, regulating chitinase activity in Streptomyces thermoviolaceus. However, the genes had a divergent orientation with respect to the PF35 promoter. Disruption of the S. coelicolor chiR gene appeared to have no obvious effect on growth, morphology, differentiation, and production of pigmented antibiotic actinorhodin and undecylprodigiosin. Moreover, the chiR disruption did not affect the overall chitinase activity.