Studies on A-factor receptor protein involved in secondary metabolism and morphorogical differentiation in Streptomyces griseus

点击翻译按钮获取中文摘要

A-factor is a representative of the autoregulatory factors, often called microbial hormones, that switch on secondary metabolism and morphogenesis in the bacterial genus Streptomyces. In Streptomyces griseus, A-factor at an extremely low concentration triggers streptomycin (Sm) production and cell differentiation by binding a repressor-type receptor protein (ArpA) and dissociating it from DNA.The purpose of this study is revealing the molecular function of ArpA.1. The target genes of ArpAAn A-factor-responsive transcriptional activator (AdpA) able to bind the promoter of strR, a pathway-specific regulatory gene responsible for transcription of other Sm biosynthetic genes, was found to be the target of ArpA.This result can explain how A-factor triggers Sm biosynthesis at a late exponential growth stage.Two DNA fragments which contain ArpA-binding site were cloned from the genome of S.griseus. Transcriptional analysis of some candidates of ArpA-target gene are proceeding. Gene disruption of these genes are also proceeding.2.3D-structure of a microbial hormone receptorCrystallization of an ArpA homologue (CrpB) of Streptomyces coelicolor was successfully achieved. Crystallographic parameters and initial phases were determined using X-ray diffraction. In near future, 3D-structure of CrpB will be revealed. Then 3D-structure of ArpA may be solved easily.