Structure and function of steptomyces RNA polymerase

步霉菌具有独特的生命周期，在形态和生理上有复杂的分化。在固体培养基上，细菌作为基质菌丝生长，菌丝延伸形成气生菌丝并最终分化为外孢子。在产孢过程中的某些阶段，它们产生各种抗生素。从大肠杆菌基因表达控制的知识来看，链霉菌基因转录的开关控制一定涉及RNA聚合酶启动子选择性的调节。为了验证这一可能性，我们首次从虾蛄中纯化了RNA聚合酶，并对其结构和功能进行了分析。从植物期菌丝体中发现的酶含有一个由hrdB基因编码的主要sigma因子，并转录一些细胞生长必需的基因。因此，我们得出结论，Esigma-B（或E-HrdB）是指数生长细胞中主要的RNA聚合酶全酶。在对RNA聚合酶进行分析的同时，还收集了一组S.griceus启动子，以便将来对次要sigma因子进行分析。

Steptomyces has a unique life cycle with a complex differentiation in morphology and physiology.On solid media, the bacteria grow as substrate mycelia which extend to form aerial hyphae and ulitimately differentiate into exospores.At certain plases during the sporulation, they produce varieties of antibiotics.From the knowledge of gene expression control in E.coli, the modulation of promoter selectivity of RNA polymerase must be involved in this switching control of gene transcription in Streptomyces.In order to test this possibility, RNA polymerase was purified for the first time from S.greseus and analyzed for its structure and function.The enzyme from vegetative-phase mycelia was found to contain a principal sigma factor encoded by the gene hrdB and to transcribe some essential genes for cell growth.Thus, we concluded that Esigma-B (or E-HrdB) is the major RNA polymerase holoenzyme in the exponentially growing cells.In parallel with the analysis of RNA polymerase, a collection of S.griceus promoters is being made for future analysis of minor sigma factors.