Characterization of the spore-pigment biosynthetic gene cluster (sah) in Streptomyces sahachiroi ATCC 33158

Abstract:

Abstract:［Objective］ A putative type II polyketide synthase (PKS) gene cluster (sah) was found in the genome sequence of Streptomyces sahachiroi ATCC 33158 by bioinformatics． In order to discover its biological function，we cloned the sah cluster and made functional analyses by gene knockout and heterologous expression．［Methods ＆ Results］Annotation of the predicted open reading frames (ORFs) by protein-protein blast revealed that the sah cluster is highly homologous with the spore-pigment biosynthetic cluster (whiE) in S． coelicolor A3 (2)，except an additional Omethyltransferase gene (sahI)．Three genes of the sah cluster，sahG，sahH and sahI，which are putatively involved in post-PKS modifications，were respectively in-frame deleted by double crossover． We observed the color of the mutant strains spores apparently changed． HPLC and LC-MS analyses demonstrated that heterologous expression of the sahminimal PKS gene and the whiE-minimal PKS gene in S．lividans ZX1 produced the same hydrophilic red pigments.［Conclusion］The sah cluster is responsible for the spore-pigment biosynthesis of S．sahachiroi ATCC 33158．It catalyzes the formation of polyketides with the same core structures as that of the whiE cluster．

Key words:Keywords: Streptomyces sahachiroi ATCC 33158，type II polyketide synthase (PKS)，gene in-frame deletion，heterologous expression，spore-pigment biosynthesis