以基因组信息为指导的深海链霉菌SCSIO T05中活性次级代谢产物挖掘

Deep-sea actinomycete is recognized as a new source of natural products due to its special gene sequence and biosynthetic pathways. Deep-sea Streptomyces sp. SCSIO T05, isolated from marine sediment of the Indian ocean, could produce abundant secondary metabolites, and a series of compounds with anthracene, indolosesquiterpene and macrolide structures were isolated from it in initial experiment. Further bioinformatics analysis revealed that most of the gene clusters were still in silence，which means more novel compounds can be synthesized by it. In order to exploit the biosynthesis potential of Streptomyces sp. SCSIO T05, genome mining technology is employed in this project and the main contents are listed as follows: 1) The target gene clusters are activated by extensive media screening and orientation optimization of the culture, knockout of biosynthesis gene clusters, gene expression regulation and heterologous expression for the biosynthesis of novel compounds. 2) Novel compounds are obtained by scale fermentation, extract and isolation, and the structures are elucidated by detailed spectroscopic analysis. 3) Biological activities, such as anti-affection and anti-tumor activities of the isolated compounds are screened to find the ones with obvious activities. The results of the project will supply significant lead compounds for the development of marine drugs with independent intellectual property rights.

深海放线菌特殊的基因序列和生物合成途径使其成为天然产物研究的战略新兴资源。我们前期研究表明从印度洋海底沉积物中分离得到的深海链霉菌SCSIO T05代谢产物丰富，现已从中分离得到一系列具有蒽环、吲哚倍半萜和大环内酯等结构的化合物，但生物信息学分析表明其大多数基因簇处仍于沉默状态，具有生产多种新颖化合物的潜力。因此，本项目拟以基因组信息为指导研究菌株对多种化合物的生产能力，主要内容包括：1) 运用培养基的广泛筛选和定向优化、生物合成基因簇的阻断、基因簇的调控表达和异源表达等基因组挖掘方法激活基因簇的表达；2) 对构建的突变株和异源表达菌株进行放大发酵和提取分离，综合运用各种色谱方法鉴定目标化合物的结构；3) 对分离得到的化合物进行抗病原菌和耐药菌、抗肿瘤等多方面的活性筛选，以期发现具有显著活性的化合物。本项目的研究成果将为开发我国具有自主知识产权的海洋药物提供先导化合物。

生物信息学分析结果表明印度洋海底沉积物中分离得到的深海链霉菌SCSIO T05含有多个次级代谢产物生物合成基因簇，具有生产多种新颖化合物的潜力。本项目综合利用各种基因工程技术手段，对该菌株次级代谢产物进行挖掘，激活了蒽醌类、mycemycin类，以及安莎霉素类等多个基因簇的表达，并通过放大发酵分离得到化合物34个；利用各种分子生物学手段确定了3类不同骨架类型化合物的生物合成基因簇及其合成过程；活性评价结果表明化合物sorbicillin和3-甲基-N-(2'-苯乙基)丁酰胺在细胞模型上对白色念珠菌生物膜形成、菌丝形态转换和致病性有明显的抑制作用,动物实验表明化合物sorbicillin对感染了白色念珠菌的小鼠具有明显的保护作用。研究成果，为新型抗感染药物的研发提供了新的先导化合物，并为利用基因工程技术挖掘海洋微生物资源提供了理论基础。

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