Mycothiol Biosynthesis and Metabolic Functions

菌硫醇生物合成和代谢功能

• 批准号: 0235705
• 负责人: Robert Fahey
• 金额: $ 37.45万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-06-01 至 2007-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235705&HistoricalAwards=false
• 关键词: Mycothiol; Biosynthesis; Metabolic; Functions

Mycothiol (MSH, AcCys-GlcN-Ins), is the major low-molecular-weight thiol produced by actinomycetes, a broad group of gram positive bacteria which include the streptomycetes and mycobacteria. Current evidence indicates that MSH has functions in actinomycetes analogous to glutathione (GSH) in GSH-producing organisms but our understanding of MSH biochemistry is still limited. The four enzymes involved in MSH biosynthesis and one enzyme involved in a novel MSH-dependent detoxification pathway have been identified in this laboratory. Mycobacterial mutants have also been obtained which are blocked at various steps of MSH biosynthesis. The present studies continue the elucidation of the metabolic biochemistry of mycothiol. The regulation of MSH biosynthesis will be examined through kinetic studies with the final two enzymes of MSH biosynthesis, MshC and MshD, and through gene replacement studies to test the role of putative MSH regulatory genes. The importance of MSH and its biosynthetic intermediates for mycobacterial sensitivity to toxins and antibiotics will be determined through studies of MSH deficient mutants blocked at various steps of MSH production. The role of MSH in the detoxification of the antibiotic rifamycin will be examined using radioactive labeling of MSH in Mycobacterium smegmatis to permit identification of MSH adducts and degradation products, and through kinetic studies of MSH-rifamycin adduct metabolism by the degradative enzyme mycothiol S-conjugate amidase.A novel antioxidant named mycothiol has been found to be produced by a class of bacteria which include the streptomycetes, the main antibiotic-producing bacteria, and the mycobacteria, the causative agents of tuberculosis and leprosy. Evidence indicates that mycothiol is involved in protecting cells against various toxins and antibiotics. This research will elucidate the factors involved in regulating mycothiol production in mycobacteria and the role of mycothiol in detoxifying the antibiotic rifamycin. The results could provide the basis for devising methods to enhance the ability of bacteria to detoxify environmental pollutants (bioremediation) and for increasing antibiotic production in streptomycete fermentations.

菌硫醇（MSH，AcCys-GlcN-Ins）是放线菌产生的主要低分子量硫醇，放线菌是一大类革兰氏阳性菌，包括链霉菌和分枝杆菌。 目前的证据表明，MSH 在放线菌中的功能类似于产生 GSH 的生物体中的谷胱甘肽 (GSH)，但我们对 MSH 生物化学的了解仍然有限。 本实验室已鉴定出参与 MSH 生物合成的四种酶和一种参与新型 MSH 依赖性解毒途径的酶。 还获得了在 MSH 生物合成的各个步骤中被阻断的分枝杆菌突变体。 目前的研究继续阐明菌硫醇的代谢生物化学。 MSH 生物合成的调节将通过 MSH 生物合成的最后两种酶 MshC 和 MshD 的动力学研究进行检查，并通过基因替换研究来测试假定的 MSH 调节基因的作用。 MSH 及其生物合成中间体对于分枝杆菌对毒素和抗生素敏感性的重要性将通过对在 MSH 生产的各个步骤中被阻断的 MSH 缺陷突变体的研究来确定。 将使用耻垢分枝杆菌中 MSH 的放射性标记来检查 MSH 在抗生素利福霉素解毒中的作用，以鉴定 MSH 加合物和降解产物，并通过降解酶菌硫醇 S-缀合物对 MSH-利福霉素加合物代谢进行动力学研究酰胺酶。已发现一种名为菌硫醇的新型抗氧化剂由一类细菌产生，其中包括链霉菌，链霉菌是主要的抗生素生产者细菌和分枝杆菌，结核病和麻风病的病原体。 有证据表明菌硫醇参与保护细胞免受各种毒素和抗生素的侵害。 这项研究将阐明参与调节分枝杆菌中菌硫醇产生的因素以及菌硫醇在抗生素利福霉素解毒中的作用。 研究结果可以为设计增强细菌解毒环境污染物能力（生物修复）的方法和增加链霉菌发酵中抗生素的产量提供基础。