Pyridoxal-5′-phosphate-dependent alkyl transfer in nucleoside antibiotic biosynthesis
Pyridoxal-5′-phosphate-dependent alkyl transfer in nucleoside antibiotic biosynthesis
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DOI：
10.1038/s41589-020-0548-3
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发表时间：
2020-06-01
影响因子：
14.8
通讯作者：
Van Lanen, Steven G.
中科院分区：
文献类型：
--
作者：
Cui, Zheng;Overbay, Jonathan;Van Lanen, Steven G.
几种核苷类抗生素的结构特征是5“-氨基-5”-脱氧核糖（ADR）通过糖苷键附加到高碳糖核苷（5 ' S，6 ' S）-5 '-C-甘氨酰尿苷（GlyU）上。GlyU进一步用N-烷基胺接头修饰，其生物合成来源尚未确定。通过结合使用同位素标记的前体的喂养实验和来自多个途径的重组蛋白的表征，已经揭示了含ADR-GlyU的核苷抗生素的N-烷基胺安装的生物合成机制。数据显示S-腺苷-L-甲硫氨酸（NAMet）作为N-烷基胺的直接前体，但是，与常规的NAMet-或脱羧的NAMet-依赖性烷基转移酶不同，该反应由吡哆醛-5 '-磷酸依赖性氨基丁酰转移酶（ABT酶）催化，使用逐步γ-置换机制，该机制将NAMet的γ-消除与氮杂-γ-加成偶联到二糖烷基受体上。除了使用一个概念上不同的策略，依赖于烷基化的甜菜碱，新发现的ABTases需要一个磷酸化的二糖烷基受体，揭示了一个隐藏的中间体的生物合成途径。
Several nucleoside antibiotics are structurally characterized by a 5 ''-amino-5 ''-deoxyribose (ADR) appended via a glycosidic bond to a high-carbon sugar nucleoside (5 ' S,6 ' S)-5 '-C-glycyluridine (GlyU). GlyU is further modified with an N-alkylamine linker, the biosynthetic origin of which has yet to be established. By using a combination of feeding experiments with isotopically labeled precursors and characterization of recombinant proteins from multiple pathways, the biosynthetic mechanism for N-alkylamine installation for ADR-GlyU-containing nucleoside antibiotics has been uncovered. The data reveal S-adenosyl-l-methionine (AdoMet) as the direct precursor of the N-alkylamine, but, unlike conventional AdoMet- or decarboxylated AdoMet-dependent alkyltransferases, the reaction is catalyzed by a pyridoxal-5 '-phosphate-dependent aminobutyryltransferase (ABTase) using a stepwise gamma-replacement mechanism that couples gamma-elimination of AdoMet with aza-gamma-addition onto the disaccharide alkyl acceptor. In addition to using a conceptually different strategy for AdoMet-dependent alkylation, the newly discovered ABTases require a phosphorylated disaccharide alkyl acceptor, revealing a cryptic intermediate in the biosynthetic pathway.