Gene-expression analysis of acidic pH shock effects on two-component systems in Streptomyces coelicolor

Abstract

Previously in our group, it was found that an acidic pH shock enhanced the production and secretion of secondary metabolites, especially actinorhodin, and activated genes for its biosysthesis in Streptomyces coelicolor A3(2). In S. coelicolor, two-component systems serve as basic stimulus-response coupling mechanism to allow the microorganism to sense and respond to changes in many different environmental conditions. In this study, transcriptional analyses by using reverse transcription-polymerase chain reaction (PCR), DNA chip, and quantitative real time-PCR were performed to investigate effects of acidic pH shock on 9 two-component systems in S. coelicolor A3(2). Two-component systems of cseC/cseB and vanS/vanR, known to be closely linked with self-protection against cell wall hydrolysis caused by external stimuli were upregulated by the pH shock. Two-component systems of afsQ2/afsQ1, ecrA2/ecrA1, ramC/ramR, ragK/ragR, chiS/chiR, and bldM, known to be positively associated with the initiation of secondary metabolism were also upregulated by the pH shock. Two-component system of cutS/cutR known to be negatively related to the secondary metabolism was, however, slightly downregulated. These results imply that the acidic pH shock induces the enhancement of the production and secretion of secondary metabolites like actinorhodin, probably by activating two-component systems associated with secondary metabolism and the integrity of cell wall.