产Macrolactins的海洋细菌X-2中Ⅰ型PKS基因簇的筛选鉴定与功能分析

Screening, Identifying and Function Analysis of Polyketide Synthase I Cluster from the Environmental Strain X-2 Which Produce Macrolactins

Macrolactins是近年来从Actinomadura sp.和Bacillus sp.等海洋来源的微生物中分离的一群24元大环内酯类化合物,具有抗菌、抗病毒和抗肿瘤等生物学活性。本室从东海海泥中分离到一株海洋细菌X-2,可产生多种Macrolactins。本研究自行设计了一套针对Ⅰ型聚酮合酶(polyketide synthase,PKS)基因中酮缩合酶(ketosynthase,KS)片段的简并引物,使用PCR方法直接克隆到了X-2基因组中的一段长约645bp的Ⅰ型KS基因片段,提交GenBank获登录号EF486351,并以之为探针筛选X-2的fosmid基因组文库,得到了3个阳性克隆,测序获得的序列经同源性分析和功能预测,初步证实获得了该菌中负责生物合成Macrolactin的部分Ⅰ型PKS基因簇的功能序列。

Macrolactins are 24-membered macrolides produced by unidentified marine bacterium, Actinomadura sp. and Bacillus sp., which exhibit both antibacterial and antitumor activities in vitro. The environmental strain X-2 which was isolated from the sediment of the East China Sea produce Macrolatin A, B and O. In this study, a set of degenerate oligonucleotide primers, designed for amplification ketosynthase（KS） domains, had been employed to identify KS gene fragments of the X-2 DNA samples. One 645 bp KS fragment（GenBank accession no. EF486351）had been cloned and used as a probe to screen the genome DNA fosmid library of X-2. Three positive clones were selected and sequenced, Homologous analysis and the function prediction of the obtained PKS gene fragments suggested that macrolactin is the Polyketide Biosynthesis Product of the gene cluster obtained in the environmental strain X-2.