Fahey R C
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA.
Annu Rev Microbiol. 2001;55:333-56. doi: 10.1146/annurev.micro.55.1.333.
Glutathione metabolism is associated with oxygenic cyanobacteria and the oxygen-utilizing purple bacteria, but is absent in many other prokaryotes. This review focuses on novel thiols found in those bacteria lacking glutathione. Included are glutathione amide and its perthiol, produced by phototrophic purple sulfur bacteria and apparently involved in their sulfide metabolism. Among archaebacteria, coenzyme M (2-mercaptoethanesulfonic acid) and coenzyme B (7-mercaptoheptanoylthreonine phosphate) play central roles in the anaerobic production of CH4 and associated energy conversion by methanogens, whereas the major thiol in the aerobic phototrophic halobacteria is gamma-glutamylcysteine. The highly aerobic actinomycetes produce mycothiol, a conjugate of N-acetylcysteine with a pseudodisaccharide of glucosamine and myo-inositol, AcCys-GlcNalpha(1 --> 1)Ins, which appears to play an antioxidant role similar to glutathione. Ergothioneine, also produced by actinomycetes, remains a mystery despite many years of study. Available data on the biosynthesis and metabolism of these and other novel thiols is summarized and key areas for additional study are identified.
谷胱甘肽代谢与产氧蓝细菌和利用氧气的紫色细菌有关，但在许多其他原核生物中并不存在。本综述重点关注在缺乏谷胱甘肽的细菌中发现的新型硫醇。其中包括谷胱甘肽酰胺及其过硫醇，由光合紫色硫细菌产生，显然参与其硫化物代谢。在古细菌中，辅酶M（2-巯基乙烷磺酸）和辅酶B（7-巯基庚酰苏氨酸磷酸）在产甲烷菌厌氧产生CH4及相关能量转换过程中起核心作用，而需氧光合盐细菌中的主要硫醇是γ-谷氨酰半胱氨酸。高度需氧的放线菌产生肌醇硫酯，它是N-乙酰半胱氨酸与葡糖胺和肌醇的假二糖的共轭物，即AcCys-GlcNα(1→1)Ins，似乎发挥着与谷胱甘肽类似的抗氧化作用。尽管经过多年研究，放线菌产生的麦角硫因仍然是个谜。总结了这些及其他新型硫醇生物合成和代谢的现有数据，并确定了需要进一步研究的关键领域。
