Identification of a novel unpaired histidine sensor kinase affecting secondary metabolism and morphological differentiation in Streptomyces acidiscabies ATCC 49003.

Two-component systems (TCSs) are an important signaling transduction pathway that adapt to changing environments. Commonly, a TCS comprises a sensor kinase that is usually an integral membrane histidine sensor kinase and a response regulator that mediates the cellular responses. Presently, however, we cloned a novel sensor kinase gene (tcsK) that is not adjacent to its cognate response regulator from Streptomyces acidiscabies that produces two secondary metabolites, thaxtomin A and WS5995B, and identified its functional involvement in the production of secondary metabolites and morphological differentiation. The elevated expression and disruption of the tcsK gene enhanced 7.1-fold and almost abolished WS5995B production in S. acidiscabies, respectively, but did not affect the production of thaxtomin A. In addition, spore formation of S. acidiscabies was decreased 120-fold by the disruption of tcsK, and the actinorhodin production of Streptomyces lividans TK24 was increased 5.7-fold by the high expression of tcsK. These results indicate that the novel unpaired tcsK gene may be related to the control of secondary metabolite production and spore formation in actinomycetes.