Horinouchi S, Beppu T
Department of Agricultural Chemistry, University of Tokyo, Japan.
Antonie Van Leeuwenhoek. 1993;64(2):177-86. doi: 10.1007/BF00873026.
Accumulating data have shown that the metabolites with a gamma-butyrolactone ring functions as an autoregulatory factor or a microbial hormone for the expression of various phenotypes not only in a variety of Streptomyces spp. but also in the distantly related bacteria. A-factor, as a representative of this type of autoregulators, triggers streptomycin biosynthesis and cellular differentiation in Streptomyces griseus. A model for the A-factor regulatory cascade on the basis of recent work is as follows. At an early step in the A-factor regulatory relay, the positive A-factor signal is first received by an A-factor receptor protein that is comparable in every aspect to eukaryotic hormone receptors, and then, via one or more regulatory steps, transmitted to an A-factor-responsive protein that binds to the upstream activation sequence of the strR gene, a regulatory gene in the streptomycin biosynthetic gene cluster. The StrR protein thus induced appears to activate the other streptomycin biosynthetic genes. This review summarizes the characteristics of A-factor as a microbial hormone and the A-factor regulatory relay leading to streptomycin production.
越来越多的数据表明，具有γ-丁内酯环的代谢产物不仅在多种链霉菌属中，而且在亲缘关系较远的细菌中，都作为一种自调节因子或微生物激素，参与各种表型的表达。作为这类自调节因子的代表，A因子可触发灰色链霉菌中链霉素的生物合成和细胞分化。基于近期研究成果的A因子调控级联模型如下。在A因子调控传递的早期阶段，正向的A因子信号首先被一种A因子受体蛋白接收，该蛋白在各个方面都与真核激素受体相当，然后，通过一个或多个调控步骤，传递给一种A因子响应蛋白，该蛋白与链霉素生物合成基因簇中的调控基因strR基因的上游激活序列结合。由此诱导产生的StrR蛋白似乎会激活其他链霉素生物合成基因。本综述总结了A因子作为微生物激素的特性以及导致链霉素产生的A因子调控传递过程。
