Identification and Characterization of Xiamycin A and Oxiamycin Gene Cluster Reveals an Oxidative Cyclization Strategy Tailoring Indolosesquiterpene Biosynthesis
Identification and Characterization of Xiamycin A and Oxiamycin Gene Cluster Reveals an Oxidative Cyclization Strategy Tailoring Indolosesquiterpene Biosynthesis
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DOI：
10.1021/ja303004g
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发表时间：
2012-05-30
影响因子：
15
通讯作者：
Zhang, Changsheng
中科院分区：
文献类型：
--
作者：
Li, Huixian;Zhang, Qingbo;Zhang, Changsheng
Xiamycin A（XMA）和oxiamycin（OXM）是具有稀有五环系统的细菌吲哚倍半萜，并且从海洋来源的链霉菌SCSIO 02999中分离。通过部分基因组测序方法鉴定了XMA/OXM的推定生物合成基因簇。18个基因被认为参与了XMA/OXM的生物合成，包括5个通过非甲羟戊酸途径合成萜烯的基因，8个编码氧化还原酶的基因，以及5个调控和抗性基因。对xia基因簇内的13个基因进行靶向破坏，以探测它们在XMA/OXM生物合成中的编码功能。破坏编码芳环羟化酶的xiaK，导致产生indosepene和少量XMA的突变体。给不产生XMA/OXM的突变体喂饲indosepene揭示indosepene是XMA/OXM生物合成的共同前体。最值得注意的是，黄素依赖性加氧酶Xia I的生化特征在于在体外将indosepene转化为XMA，揭示了一种不寻常的氧化环化策略，定制indolosesquiterpene生物合成。
Xiamycin A (XMA) and oxiamycin (OXM) are bacterial indolosesquiterpenes featuring rare pentacyclic ring systems and are isolated from a marine-derived Streptomyces sp. SCSIO 02999. The putative biosynthetic gene cluster for XMA/OXM was identified by a partial genome sequencing approach. Eighteen genes were proposed to be involved in XMA/OXM biosynthesis, including five genes for terpene synthesis via a non-mevalonate pathway, eight genes encoding oxidoreductases, and five genes for regulation and resistance. Targeted disruptions of 13 genes within the xia gene cluster were carried out to probe their encoded functions in XMA/OXM biosynthesis. The disruption of xiaK, encoding an aromatic ring hydroxylase, led to a mutant producing indosespene and a minor amount of XMA. Feeding of indosespene to XMA/OXM nonproducing mutants revealed indosespene as a common precursor for XMA/OXM biosynthesis. Most notably, the flavin dependent oxygenase XiaI was biochemically characterized in vitro to convert indosespene to XMA, revealing an unusual oxidative cyclization strategy tailoring indolosesquiterpene biosynthesis.