在植物和细菌中,Ⅲ型聚酮合酶能够产生种类多样的次生代谢产物.在药用植物内生放线菌A00122的发酵产物中,分离到了一个已知的Ⅲ型聚酮类化合物gErMICIdIn.对A00122菌株建立了基因组文库,根据已知的同源基因SCO7221设计引物作为探针对文库进行PCr筛选,并通过SOuTHErn杂交的方法从阳性克隆5-3-10中定位了包含gErMI-CIdIn基因的片段,经测序得到长度为1 185 bP的完整合成基因.该基因的获得为深入研究Ⅲ型聚酮合酶的底物选择性,通过定向改造的方法获得非天然Ⅲ型聚酮类化合物提供了重要基础.The type Ⅲ polyketide synthases(PKSs) generate backbones of a variety of plant and bacterial secondary metabolites.In previous work,many endophytic actinomycetes were isolated from different pharmaceutical plants,whereas the secondary metabolic products of theses strains were studied.A known type Ⅲ PKSs compound,germicidin,was isolated from one of the endophytic actinomycete A00122.Primers for A00122 genomic library screening were designed based on the homologous gene Sco7221 and the PCR product was used as the probe for Southern blotting.Finally,a 1 185 bp gene was cloned and sequenced from one of the positive cosmid 5-3-10,which was identified to be involved in the biosynthesis of germicidin from A00122.Since it is the first germicicin biosynthetic gene from endophytic actinomycetes,this study provides an important foundation for accepting chemically and structurally divergent unnatural novel type Ⅲ PKSs compounds by directed mutation of proteins.国际合作项目(DFA30970);教育部科学技术研究重大项目(306010
