变铅青链霉菌高效异源表达宿主SBT5的构建

Construction of Streptomyces lividans SBT5 as an efficient heterologous expression host

以变铅青链霉菌TK24为出发菌株,依次敲除钙依赖抗生素(CDA)、放线紫红素(ACT)和十一烷基灵菌红素(RED)这3个内源抗生素的生物合成基因簇,同时在钙依赖抗生素基因簇原位整合了来自棒状链霉菌的全局性调控基因afsRScla,构建得到变铅青链霉菌菌株SBT5。将来自天蓝色链霉菌的放线紫红素生物合成基因簇导入SBT5中,接合子产生大量蓝色的放线紫红素,而出发菌株TK24只产微量蓝色抗生素;SBT5接合子的ACT产量也显著高于导入了额外act基因簇拷贝的出发菌株接合子。SBT5菌株次级代谢背景清晰,不产色素类抗生素和抗细菌抗生素,可作为高效宿主用于次级代谢产物基因簇的异源表达和筛选。

Three gene clusters controlling the biosynthesis of the antibiotics actinorhodin （ACT）, undecylprodigiosin （RED） and calcium-dependent antibiotic （CDA） were sequentially knockouted by gene replacements from the chromosome of Streptornyces lividans TK24 to derive SBTS. In SBTS, the global regulatory genes afsRS,l, from Streptomyces clavuligerus was integrated in the place of the cda gene cluster. The act gene cluster from Streptornyces coelicolor was introduced into SBT5 to test its ca- pability of expressing secondary gene cluster. The resulting SBT5 exconjugants overproduced ACT com- paring with wild-type strains harboring double copies of the act gene cluster. SBT5 is an efficient host with a clean secondary metabolism background suitable for heterologously expressing and screening sec ondary metabolic gene clusters.