The Regulation of Carbon Utilization in Streptomyces

9316912威斯特法林链霉菌是革兰氏阳性土壤细菌，由于其极其复杂的形态发育和产生人类和动物保健所用的大部分抗生素的次生代谢物，因此特别令人感兴趣。虽然对这些细菌的分子生理学了解很少，但很明显，碳利用的调节在形态发育和抗生素生物合成的基因表达途径中都是至关重要的。为了了解链霉菌分解代谢的控制机制，我们正在研究甲壳素利用基因家族的调控。甲壳素是一种复杂的碳水化合物，也是土壤中碳的主要来源。几丁质酶的合成受到葡萄糖的强烈抑制和几丁质的强烈诱导。在初步工作中，我们已经为至少一种甲壳素建立了这一规则。在初步工作中，我们已经确定了至少一个几丁质酶基因chi63的调控发生在转录启动水平。我们对chi63启动子区域内的突变进行了系统的分析，并使用与xy1E报告基因的转录融合来鉴定定义葡萄糖抑制和几丁质诱导几丁质酶合成途径的染色体突变。我们正在定义决定调控和启动子活性的几丁质酶启动子的元件；开始一项研究，以识别和表征促进链霉菌分解代谢抑制的全球调控的基因。%我们希望通过这项工作，有助于理解一类重要细菌的基因调控，在这类细菌中，人们对基因表达的控制方式知之甚少。***

9316912 Westpheling Streptomyces are Gram-positive soil bacteria that are of special interest because of their remarkably complex morphological development and because they produce as secondary metabolites most of the antibiotics used in human and animal health care. Although little is understood about the molecular physiology of these bacteria, it is apparent that the regulation of carbon utilization is of central importance in the gene expression pathways for both morphological development and antibiotic biosynthesis. To gain an understanding of the mechanism of catabolite control in Streptomyces we are studying the regulation of a family of genes involved in the utilization of chitin, a complex carbohydrate and a major source of carbon in the soil. The synthesis of chitinase enzymes is tightly repressed by glucose and strongly induced by chitin. In preliminary work we have established that regulation for at least one of the chitin. In preliminary work we have established that regulation for at least one of the chitinase genes, chi63, occurs at the level of transcription initiation. We have been a systematic analysis of mutations within the promoter region of chi63 and used a transcriptional fusion to the xy1E reporter gene, to identify chromosomal mutations that define the pathway for glucose repression and chitin induction of chitinase synthesis. We are defining the elements of the chitinase promoters that determine regulation and promoter activity; beginning a study to identify and characterize genes that act to facilitate the global regulation of catabolite repression in Streptomyces. %%% We hope as a result of this work to contribute to the understanding of gene regulation in an important class of bacteria where relatively little is known about the way in which gene expression is controlled. ***