Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, People's Republic of China.
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom.
Proc Natl Acad Sci U S A. 2018 Feb 6;115(6):1340-1345. doi: 10.1073/pnas.1711603115. Epub 2018 Jan 22.
Gentamicin C complex from remains a globally important antibiotic, and there is revived interest in the semisynthesis of analogs that might show improved therapeutic properties. The complex consists of five components differing in their methylation pattern at one or more sites in the molecule. We show here, using specific gene deletion and chemical complementation, that the gentamicin pathway up to the branch point is defined by the selectivity of the methyltransferases GenN, GenD1, and GenK. Unexpectedly, they comprise a methylation network in which early intermediates are ectopically modified. Using whole-genome sequence, we have also discovered the terminal 6'--methyltransfer required to produce gentamicin C2b from C1a or gentamicin C1 from C2, an example of an essential biosynthetic enzyme being located not in the biosynthetic gene cluster but far removed on the chromosome. These findings fully account for the methylation pattern in gentamicins and open the way to production of individual gentamicins by fermentation, as starting materials for semisynthesis.
庆大霉素 C 复合物仍然是一种具有全球重要意义的抗生素，人们对其类似物的半合成重新产生了兴趣，这些类似物可能具有改善的治疗特性。该复合物由五个成分组成，这些成分在分子的一个或多个位点上的甲基化模式不同。我们在这里使用特定的基因缺失和化学互补表明，庆大霉素途径直到分支点是由甲基转移酶 GenN、GenD1 和 GenK 的选择性定义的。出乎意料的是，它们构成了一个甲基化网络，其中早期中间体被异位修饰。我们还利用全基因组序列发现了产生庆大霉素 C2b 从 C1a 或庆大霉素 C1 从 C2 所需的末端 6'--甲基转移酶，这是一个例子，说明必需的生物合成酶不是位于生物合成基因簇中，而是远离染色体上。这些发现充分说明了庆大霉素的甲基化模式，并为通过发酵生产单个庆大霉素开辟了道路，这些庆大霉素可作为半合成的起始原料。
