Effects of transcriptional mode on promoter substitution and tandem engineering for the production of epothilones in Myxococcus xanthus

Abstract

Promoter optimization is an economical and effective approach to overexpress heterologous genes and improve the biosynthesis of valuable products. In this study, we swapped the original promoter of the epothilone biosynthetic gene cluster in Myxococcus xanthus with two endogenous strong promoters PpilA and PgroEL1, respectively, which, however, decreased the epothilone production ability. The transcriptional abilities by the two promoters were found to be bloomed in the growth stage but markedly decreased after the growth, whereas the original promoter Pepo functioned majorly after the exponential growth stage. Tandem repeat engineering on the original promoter Pepo remarkably increased epothilone production. The tandem promoter exerted similar expressional pattern as Pepo did in M. xanthus. We demonstrated that differential transcriptional modes markedly affected the efficiency of promoters in controlling the gene expressions for the production of the secondary metabolite epothilones. Our study provides an insight into exploiting powerful promoters to produce valuable secondary metabolites, especially in host with limited known promoters.