Metabolic coupling of two small-molecule thiols programs the biosynthesis of lincomycin A
作者:Qunfei Zhao、Min Wang、Dongxiao Xu、Qinglin Zhang、Wen Liu
DOI:10.1038/nature14137
日期:2015.2
Mycothiol and ergothioneine are shown to have important roles in the biosynthesis of lincomycin A, a sulfur-containing antibiotic that is used to treat severe Gram-positive bacterial infections in people who cannot receive penicillin antibiotics. The biosynthetic origins of sulfur atoms found in natural products â or secondary metabolites â are not well understood. Mycothiol (MSH) is a cysteinyl pseudo-disaccharide found in Gram-positive actinobacteria, and the conjugation of this thiol-containing compound to electrophilic toxins facilitates their excretion from the bacterial cell. Actinomycetes also produce another thiol, ergothioneine (EGT), a histidine betaine derivative of unknown function. In this paper, the authors showed that MSH and EGT have important roles in the biosynthesis of lincomycin A, a sulfur-containing antibiotic that is used to treat severe Gram-positive bacterial infections in people who cannot receive penicillin antibiotics. Low-molecular-mass thiols in organisms are well known for their redox-relevant role in protection against various endogenous and exogenous stresses1,2,3. In eukaryotes and Gram-negative bacteria, the primary thiol is glutathione (GSH), a cysteinyl-containing tripeptide. In contrast, mycothiol (MSH), a cysteinyl pseudo-disaccharide, is dominant in Gram-positive actinobacteria, including antibiotic-producing actinomycetes and pathogenic mycobacteria. MSH is equivalent to GSH, either as a cofactor or as a substrate, in numerous biochemical processes4, most of which have not been characterized, largely due to the dearth of information concerning MSH-dependent proteins. Actinomycetes are able to produce another thiol, ergothioneine (EGT), a histidine betaine derivative that is widely assimilated by plants and animals for variable physiological activities5. The involvement of EGT in enzymatic reactions, however, lacks any precedent. Here we report that the unprecedented coupling of two bacterial thiols, MSH and EGT, has a constructive role in the biosynthesis of lincomycin A, a sulfur-containing lincosamide (C8 sugar) antibiotic that has been widely used for half a century to treat Gram-positive bacterial infections6,7,8,9. EGT acts as a carrier to template the molecular assembly, and MSH is the sulfur donor for lincomycin maturation after thiol exchange. These thiols function through two unusual S-glycosylations that program lincosamide transfer, activation and modification, providing the first paradigm for EGT-associated biochemical processes and for the poorly understood MSH-dependent biotransformations, a newly described model that is potentially common in the incorporation of sulfur, an element essential for life and ubiquitous in living systems.
生物合成中的硫原子来源——或称次生代谢物——尚未得到充分理解。Mycothiol (MSH)是一种半胱氨酸类假二糖,存在于革兰氏阳性放线菌中,这种含硫化合物与亲电性毒素的结合有助于它们从细菌细胞中排出。放线菌还产生另一种硫醇——麦角硫因(ergothioneine,EGT),这是一种组氨酸甜菜碱衍生物,功能尚不清楚。在这篇论文中,作者指出,MSH和EGT在生物合成中的硫原子来源——或称次生代谢物——尚未得到充分理解。Mycothiol (MSH)是一种半胱氨酸类假二糖,存在于革兰氏阳性放线菌中,这种含硫化合物与亲电性毒素的结合有助于它们从细菌细胞中排出。放线菌还产生另一种硫醇——麦角硫因(ergothioneine,EGT),这是一种组氨酸甜菜碱衍生物,功能尚不清楚。在这篇论文中,作者指出,MSH和EGT在生物合成中的硫原子来源——或称次生代谢物——尚未得到充分理解。Mycothiol (MSH)是一种半胱氨酸类假二糖,存在于革兰氏阳性放线菌中,这种含硫化合物与亲电性毒素的结合有助于它们从细菌细胞中排出。放线菌还产生另一种硫醇——麦