Glycosylation Steps during Spiramycin Biosynthesis in Streptomyces ambofaciens: Involvement of Three Glycosyltransferases and Their Interplay with Two Auxiliary Proteins
Glycosylation Steps during Spiramycin Biosynthesis in Streptomyces ambofaciens: Involvement of Three Glycosyltransferases and Their Interplay with Two Auxiliary Proteins
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DOI：
10.1128/aac.01602-09
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发表时间：
2010-07-01
影响因子：
4.9
通讯作者：
Pernodet, Jean-Luc
中科院分区：
文献类型：
--
作者：
Hoang Chuong Nguyen;Karray, Fatma;Pernodet, Jean-Luc
产氨链霉菌合成螺旋霉素，一种用于人类医学的16元大环内酯类抗生素。螺旋霉素分子由I型聚酮合酶合成的聚酮内酯环（platenolyde）组成，其上依次连接三个脱氧己糖（霉胺糖、福洛胺糖和霉卡糖）。这些糖是螺旋霉素抗菌活性所必需的。我们以前确定了四个螺旋霉素生物合成基因簇预测编码糖基转移酶的基因。我们分别删除了这四个基因中的每一个，并表明其中三个是螺旋霉素生物合成所必需的。通过鉴定相应突变株积累的生物合成中间产物，确定了三种糖基转移酶在螺旋霉素生物合成中的作用。这导致了对负责三种糖中的每一种的附着的糖基转移酶的鉴定。此外，两个基因编码推定的糖基转移酶辅助蛋白也确定了螺旋霉素生物合成基因簇。当这两个基因被删除，其中一个被发现是螺旋霉素的生物合成。然而，分析的生物合成中间体积累的突变株缺乏每个辅助蛋白（或两者），连同互补实验，揭示了糖基转移酶与辅助蛋白的相互作用。其中一个辅助蛋白与转移霉胺糖和福洛胺的两种糖基转移酶有效地相互作用，而另一个辅助蛋白仅与霉胺糖基转移酶相互作用。
Streptomyces ambofaciens synthesizes spiramycin, a 16-membered macrolide antibiotic used in human medicine. The spiramycin molecule consists of a polyketide lactone ring (platenolide) synthesized by a type I polyketide synthase, to which three deoxyhexoses (mycaminose, forosamine, and mycarose) are attached successively in this order. These sugars are essential to the antibacterial activity of spiramycin. We previously identified four genes in the spiramycin biosynthetic gene cluster predicted to encode glycosyltransferases. We individually deleted each of these four genes and showed that three of them were required for spiramycin biosynthesis. The role of each of the three glycosyltransferases in spiramycin biosynthesis was determined by identifying the biosynthetic intermediates accumulated by the corresponding mutant strains. This led to the identification of the glycosyltransferase responsible for the attachment of each of the three sugars. Moreover, two genes encoding putative glycosyltransferase auxiliary proteins were also identified in the spiramycin biosynthetic gene cluster. When these two genes were deleted, one of them was found to be dispensable for spiramycin biosynthesis. However, analysis of the biosynthetic intermediates accumulated by mutant strains devoid of each of the auxiliary proteins (or of both of them), together with complementation experiments, revealed the interplay of glycosyltransferases with the auxiliary proteins. One of the auxiliary proteins interacted efficiently with the two glycosyltransferases transferring mycaminose and forosamine while the other auxiliary protein interacted only with the mycaminosyltransferase.