Fosfomycin Biosynthesis via Transient Cytidylylation of 2-Hydroxyethylphosphonate by the Bifunctional Fom1 Enzyme
Fosfomycin Biosynthesis via Transient Cytidylylation of 2-Hydroxyethylphosphonate by the Bifunctional Fom1 Enzyme
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DOI：
10.1021/acschembio.7b00419
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发表时间：
2017-08-01
影响因子：
4
通讯作者：
Kuzuyama, Tomohisa
中科院分区：
文献类型：
--
作者：
Cho, Su-Hee;Kim, Seung-Young;Kuzuyama, Tomohisa
磷霉素是一种广谱膦酸盐抗生素，临床上用于治疗膀胱炎、中耳炎等。其生物合成始于磷酸烯醇式丙酮酸磷酸变位酶Fom 1催化形成碳磷键。我们确定了一个额外的胞苷酰转移酶（CyTase）结构域在Fom 1的N-末端除了磷酸烯醇丙酮酸磷酸变位酶结构域在Fom 1的C-末端。在这里，我们证明了Fom 1是双功能的，并且Fom 1 CyTase结构域催化2-羟乙基膦酸酯（HEP）中间体的胞苷酰化以产生胞苷酰-HEP。基于Fom 1的这一新功能，我们提出了一种修正的磷霉素生物合成途径，其中包括瞬时CMP结合的中间体。通过生物合成中间体的这种瞬时胞苷酰化的生物合成机制的鉴定从根本上推进了对自然界中膦酸盐生物合成的理解。胞苷酰-HEP结合的CyTase结构域的晶体结构为底物特异性提供了基础，并揭示了在CyTase家族的其他成员中未发现的独特催化元件。
Fosfomycin is a wide-spectrum phosphonate antibiotic that is used clinically to treat cystitis, tympanitis, etc. Its biosynthesis starts with the formation of a carbon-phosphorus bond catalyzed by the phosphoenolpyruvate phosphomutase Fom1. We identified an additional cytidylyltransferase (CyTase) domain at the Fom1 N-terminus in addition to the phosphoenolpyruvate phosphomutase domain at the Fom1 C-terminus. Here, we demonstrate that Fom1 is bifunctional and that the Fom1 CyTase domain catalyzes the cytidylylation of the 2-hydroxyethylphosphonate (HEP) intermediate to produce cytidylyl-HEP. On the basis of this new function of Fom1, we propose a revised fosfomycin biosynthetic pathway that involves the transient CMP-conjugated intermediate. The identification of a biosynthetic mechanism via such transient cytidylylation of a biosynthetic intermediate fundamentally advances the understanding of phosphonate biosynthesis in nature. The crystal structure of the cytidylyl-HEP-bound CyTase domain provides a basis for the substrate specificity and reveals unique catalytic elements not found in other members of the CyTase family.