天蓝色链霉菌调控基因-tcrA功能的初步研究

Functional analyses of TcrA-a TPR-containing regulatory protein in Streptomyces coelicolor A3(2)

天蓝色链霉菌的开放阅读框SCO5433编码一个含有TPR(Tetratricopeptide repeat)结构域的调控蛋白。该基因的阻断突变株表现出孢子颜色加深和色素产量增加的表型变化。孢子颜色的加深在以葡萄糖或甘露醇为碳源的MM培养基上表现明显;色素产量的增加在以甘露醇为碳源的MM培养基和MS培养基上表现最为明显;插片培养结合光学显微镜观察并没有发现突变株在形态分化上有显著变化;这些发现预示着可能存在一个SCO5433参与的调控途径,在一定条件下,这一途径对天蓝色链霉菌次级代谢可能起着负调控作用,而与形态分化无关。

In Streptomyces coelicolor A3 （2）, SCO5433 encodes a TPR domain containing protein designated TcrA （TPR containing regulator A）. TcrA is similar in amino acid sequence to MsR, a well-characterized global regulatory protein in S. coelicolor A3 （2）. Disruption of tcrA enhanced the production of spore pigment on MM containing glucose or mannitol and also resulted in more diffusible pigment production on MM containing mannitol or MS agar medium, but no significant effects on morphological differentiation were observed. Complementation of tcrA mutation restored the phenotype of tcrA mutant to that of the wild-type strain. These results suggest that tcrA is involved in the regulation of secondary metabolism under defined conditions. In S. coelicolor A3（2）, the AfsK/AfsR system positively regulates the production of secondary metabolites while the results of our work suggest that there might be a TcrA-dependent pathway that negatively regulates secondary metabolism.