NsdB——天蓝色链霉菌A3(2)中一个负调控抗生素产量蛋白的研究

TPR(tetratricopeptide repeat)是在很多蛋白中均被发现到的一个含有34个氨基酸的蛋白重复序列,其基本功能是参与蛋白间的相互作用。天蓝色链霉菌A3(2)中有70个蛋白含有类TPR结构域,NsdA是其中的一个,研究发现该蛋白对天蓝色链霉菌的产孢和产素都有负调控作用。本研究中发现基因SCO7252和SCO1593编码含TPR结构的蛋白,中断SCO7252基因后菌株放线紫红素和钙依赖抗生素产量均提高,但形态分化没有明显变化,基因SCO1593中断后菌株在产孢产素及形态等各方面均未受到影响。基因SCO7252被命名为nsdB,RT-PCR分析表明,该基因在生长30h时开始表达。通过生物信息分析表明,天蓝色链霉菌的70个含类TPR结构的蛋白中有32个仅含该结构域,有25个另外含有DNA结合区域,这些暗示着它们可能直接控制基因的表达。

NsdB,a TPR-like-domain-containing protein negatively affecting production of antibiotics in Streptomyces coelicolor A3(2)

Tetratricopeptide repeat (TPR) domains usually mediate protein-protein interactions. NsdA, one of the 70 proteins containing TPR-like domains in Streptomyces coelicolor A3(2), was previously found to negatively control sporulation and antibiotic production. Here we show that elimination of SCO7252, which encodes another of these proteins, also caused overproduction of two antibiotics, actinorhodin and CDA, but did not affect morphological differentiation. Disruption of SCO1593, encoding another of the family, had no obvious phenotypic effects. In surface-grown cultures, expression of SCO7252, which was named nsdB, was initiated at about 30 h, like that of nsdA. Analysis in silico of the 70 predicted TPR-like-containing proteins of S. coelicolor showed that 32 of them contained only TPR-like domains, and 25 of the remainder contained additional DNA-binding domains, implying that they might control gene expression directly.