Methionine Recycling Pathways in Klebsiella

克雷伯氏菌中的蛋氨酸回收途径

• 批准号: 6438402
• 负责人: Jeffrey G Lawrence
• 金额: $ 21.46万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6438402
• 关键词: Klebsiella; aminoacid metabolism; biochemical evolution; cysteine; functional /structural genomics; fusion gene; gene targeting; genetic regulation; methionine; microorganism metabolism; molecular cloning; nucleic acid sequence; regulatory gene; reporter genes

DESCRIPTION (provided by applicant): Sulfur is a critical component of numerous universally-distributed, indispensable biomolecules. In most bacteria, sulfur is assimilated organically into cysteine, which serves as the sulfur donor for all other sulfurbearing molecules in the cell. Methionine is made is a separately controlled process, using cysteine as a sulfur donor. Klebsiella aerogenes is distinct from the related model organism Escherichia coli in employing at least 2 distinct pathways to recycle methionine-bound sulfur back into the cysteine pool. One pathway appears specific in directing reverse transsulfurylation (creating cysteine from methionine), and the likely generates an inorganic sulfur intermediate from methanethiol. Therefore, sulfur amino-acid metabolism in E. coli - used as a model organism for understanding the physiology of numerous organisms by homology - represents remnant metabolism and provides an incomplete view of this universally distributed physiology. These recycling pathways may play a role in Klebsiella exploitation of a pathogenic lifestyle, where sulfur may be limiting, and may play significant roles in recycling abundant global pools of organic sulfur compounds. Using genetic and molecular methods, these recycling pathways will be examined. (1) The identified genes for cysteine and methionine biosyntheses will be characterized physically and genetically via insertion mutagenesis, gene knock-out and gene fusion. (2) Insertion mutagenesis will define each methionine recycling pathway genetically. Both enzyme assays and nutritional testing will elucidate the steps of each recycling pathway. (3) Fusions to the lacZ reporter gene will be used to identify global regulatory proteins, and to infer their synergistic modes of action. In this way, characterization of these pathways sheds light on the evolution of complex metabolism, and on the selective forces that lead to gene acquisition, gene loss, and genome change.

描述(由申请人提供)：硫磺是许多 普遍分布的、不可或缺的生物分子。在大多数细菌中，硫 被有机同化成半胱氨酸，半胱氨酸作为硫磺供体 细胞中所有其他含硫分子。蛋氨酸的制造是一个单独控制的过程，使用半胱氨酸作为硫磺供体。克雷伯氏菌 产气菌与相关的模式生物大肠杆菌在 使用至少两条不同的途径回收蛋氨酸结合的硫磺 进入半胱氨酸池。有一条路径在引导反向方向时似乎是特定的 转硫基作用(从蛋氨酸生成半胱氨酸)，以及可能的 从甲硫醇生成一种无机硫中间体。因此，硫磺 大肠杆菌中的氨基酸代谢--作为一种了解 许多生物体的生理学由同源代表残留物 新陈代谢，并提供了一个普遍分布的不完整的观点 生理学。这些循环途径可能在克雷伯氏菌的利用中发挥作用 一种致病的生活方式，其中硫可能是有限的，并可能起作用 在回收丰富的全球有机硫气库方面发挥重要作用 化合物。使用遗传和分子方法，这些循环途径将 接受检查。(1)已鉴定的半胱氨酸和蛋氨酸生物合成基因 将通过插入突变来确定其物理和遗传特征， 基因敲除和基因融合。(2)插入突变将定义每个 蛋氨酸循环途径的遗传。酶分析和营养学检测 测试将阐明每条回收途径的步骤。(3)融合发展 LacZ报告基因将用于识别全球调控蛋白，并 推断它们的协同作用模式。通过这种方式，这些特征的描述 途径揭示了复杂新陈代谢的进化，以及 导致基因获取、基因丢失和基因组改变的选择性力量。