Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
Cell Chem Biol. 2019 Apr 18;26(4):493-501.e5. doi: 10.1016/j.chembiol.2018.12.004. Epub 2019 Jan 31.
Malayamycin A is an unusual bicyclic C-nucleoside, with interesting antiviral, antifungal, and anticancer bioactivity. We report here the discovery and characterization of the biosynthetic pathway to malayamycin by using genome mining of near-identical clusters both from the known producer Streptomyces malaysiensis and from Streptomyces chromofuscus. The key precursor 5'-pseudouridine monophosphate (5'-Ψ-MP) is supplied chiefly through the action of MalD, a TruD-like pseudouridine synthase. In vitro assays showed that MalO is an enoylpyruvyltransferase acting almost exclusively on 5'-Ψ-MP rather than 5'-UMP, while in contrast the counterpart enzyme NikO in the nikkomycin pathway readily accepts either substrate. As a result, deletion of malD in S. chromofuscus coupled with introduction of the gene for NikO led to production of non-natural N-malayamycin, as well as malayamycin A. Conversely, cloning malO into the nikkomycin producer Streptomyces tendae in place of nikO diverted biosynthesis toward C-nucleoside formation.
马莱霉素 A 是一种不寻常的双环 C-核苷，具有有趣的抗病毒、抗真菌和抗癌生物活性。我们在这里报告了通过对来自已知产菌马来西亚链霉菌和变色链霉菌的近同源簇进行基因组挖掘，发现和表征了马莱霉素生物合成途径。关键前体 5'-假尿嘧啶核苷酸（5'-Ψ-MP）主要通过 MalD 的作用提供，MalD 是一种 TruD 样假尿嘧啶合酶。体外测定表明 MalO 是一种烯酰基吡喃酮基转移酶，主要作用于 5'-Ψ-MP 而不是 5'-UMP，而 nikkomycin 途径中的对应酶 NikO 则容易接受两种底物。结果，在变色链霉菌中缺失 malD 并引入 NikO 的基因导致产生非天然的 N-马莱霉素 A，以及马莱霉素 A。相反，将 malO 克隆到 nikkomycin 产生菌链霉菌 tendae 中取代 nikO，使生物合成转向 C-核苷形成。
