Genetic Analysis of Global Streptomyces Antibiotic Regulation

链霉菌，丝状土壤细菌，具有两个特征，使其成为有吸引力的研究原核生物：它们发育成复杂的，多细胞的，分化的菌落，它们产生大量的次生代谢物，其中许多是有用的抗生素。抗生素的产生通常伴随着形态分化，开始于营养生长和孢子前分化菌丝的产生之间的过渡。本研究的长期目标是发现调控抗生素合成的基因，了解它们的功能，并确定它们在控制抗生素基因表达的调控网络中的功能关系。该提案的直接目标集中在以前NSF资助时期发现的三个遗传元素：absA， abb和mia。研究将沿着以下思路进行：absa编码的信号转导系统对抗生素基因表达施加全局负性控制的机制将被确定。遗传学、分子遗传学和生化实验将：a)表征AbsA1/A2“传感器激酶”和反应调节蛋白的功能重要区域和相互作用；b)确定蛋白磷酸化在absa介导的调控中的作用；c)探索absA调节抗生素“通路特异性调节因子”表达的遗传途径。2. abb基因及其可能的基因产物RNaseIII将通过RNaseIII （absB）零表型的测定、对S. coelicolor RNaseIII的功能研究和候选RNaseIII靶点的鉴定来进行表征。3. 190 nt mia序列对抗生素基因表达具有多拷贝抑制作用，我们将对其进行表征，以确定该序列的功能区域。本研究的结果有望阐明链霉菌基因表达调控程序的各个方面，并扩大我们对微生物多细胞分化的理解。

Champness 9604055 Streptomycetes, filamentous soil bacteria, possess two characteristics that make them attractive prokaryotes for study: they develop into complex, multicellular, differentiated colonies and they produce a vast array of secondary metabolites, many of which are useful as antibiotics. Antibiotic production is usually coupled to morphological differentiation, beginning at the transition between vegetative growth and production of pre-spore differentiated hyphae. The long term goal of this research is to discover the genes that regulate antibiotic synthesis, to understand how they function, and to determine their functional relationships in the regulatory network controlling antibiotic gene expression. The immediate objectives of this proposal focus on three genetic elements discovered in previous NSF funding periods: absA, absB and mia. Research will proceed along the following lines: 1. The mechanism by which the absA-encoded signal transduction system exerts global negative control over antibiotic gene expression will be determined. Genetic, molecular genetic and biochemical experiments will: a) characterize functionally important regions and interactions of the AbsA1/A2 "sensor-kinase" and response regulator proteins; b) establish the role of protein phosphorylation in AbsA-mediated regulation; and c) explore the genetic pathway through which absA regulates expression of the antibiotic "pathway-specific regulators." 2. The absB gene and its probable gene product, an RNaseIII, will be characterized through determination of the RNaseIII (absB) null phenotype, functional studies on the S. coelicolor RNaseIII, and identification of candidate RNaseIII targets. 3. The 190 nt mia sequence, which exerts multi-copy inhibition of antibiotic gene expression, will be characterized to determine the functional regions of the sequence. The results of the proposed work promise to elucidate aspec ts of the regulatory programs controlling streptomycete gene expression, and to expand our understanding of microbial multicellular differentiation.