Gene cluster responsible for validamycin biosynthesis in Streptomyces hygroscopicus subsp jinggangensis 5008
Gene cluster responsible for validamycin biosynthesis in Streptomyces hygroscopicus subsp jinggangensis 5008
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DOI：
10.1128/aem.71.9.5066-5076.2005
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发表时间：
2005-09-01
影响因子：
4.4
通讯作者：
Deng, ZX
中科院分区：
文献类型：
--
作者：
Yu, Y;Bai, LQ;Deng, ZX
从吸水链霉菌亚种中鉴定出一种广泛用于水稻纹枯病防治的氨基环素类抗生素--伐他霉素的生物合成基因簇。利用异源探针acbc，将放线菌产生的阿卡波糖生物合成基因簇中的D-七糖7-磷酸环化成2-epi-5-epi-valiolone的基因ACBC应用于井冈5008菌株。菌株SE50/110。染色体上这一簇的30kb DNA片段的缺失导致了有效霉素生产的损失，证实了该基因簇直接参与了这种重要植物保护剂的生物合成。测序的6-kb片段包含Vala(编码一个假定的环化酶的ACBC同源物)和另外两个完整的开放阅读框(valB和VaIC，分别编码一个假定的腺苷转移酶和一个激酶)，它们被组织成一个操纵子。Vala的功能在遗传上被证明是有效霉素生产所必需的，生化上证明它是利用在大肠杆菌中异源过表达的Vala蛋白，在体外将D-七糖7-磷酸环化为2-表-5-表-valiolone。所获得的信息将为进一步详细分析完整的生物合成途径铺平道路，这将导致对伐他霉素生物合成的全面了解。
A gene cluster responsible for the biosynthesis of validamycin, an aminocyclitol antibiotic widely used as a control agent for sheath blight disease of rice plants, was identified from Streptomyces hygroscopicus subsp. jinggangensis 5008 using heterologous probe acbC, a gene involved in the cyclization Of D-sedoheptulose 7-phosphate to 2-epi-5-epi-valiolone of the acarbose biosynthetic gene cluster originated from Actinoplanes sp. strain SE50/110. Deletion of a 30-kb DNA fragment from this cluster in the chromosome resulted in loss of validamycin production, confirming a direct involvement of the gene cluster in the biosynthesis of this important plant protectant. A sequenced 6-kb fragment contained valA (an acbC homologue encoding a putative cyclase) as well as two additional complete open reading frames (valB and vaIC, encoding a putative adenyltransferase and a kinase, respectively), which are organized as an operon. The function of ValA was genetically demonstrated to be essential for validamycin production and biochemically shown to be responsible specifically for the cyclization Of D-sedoheptulose 7-phosphate to 2-epi-5-epi-valiolone in vitro using the ValA protein heterologously overexpressed in E. coli. The information obtained should pave the way for further detailed analysis of the complete biosynthetic pathway, which would lead to a complete understanding of validamycin biosynthesis.