Enhanced Tunicamycin Biosynthesis in bldG Overexpressed Streptomyces clavuligerus

Abstract

Tunicamycin is a nucleoside type antibiotic with a potent antibacterial activity. Tunicamycin gene cluster inStreptomyces clavuligeruslacks a cluster-situated regulator (CSR). Therefore, there is no information about its regulation in the cell. To have an insight about the regulation of tunicamycin biosynthesis, the possible effects of BldG pleiotropic regulator involved in the control of secondary metabolite production inS. clavuligeruswere investigated. To overexpressbldGin the cell, strains containing multiple copies of the gene expressed from P(glpF)promoter ofS. clavuligeruspLB1, and an additionalbldGintegrated in the chromosome ofS. clavuligeruspLB2, were constructed.S. clavuligeruspLB1 andS. clavuligeruspLB2 fermentations resulted in 16.4- and 13.8-fold higher specific tunicamycin titers, respectively, in comparison to wild type by confirming quantitative reverse-transcription PCR (qRT-PCR) data. However, qRT-PCR expression analysis of tunicamycin genes inS. clavuligerus Delta bldGconstructed by Bignell with coworkers [1] showed that gene expressions at T-36(except forSCLAV_4274andSCLAV_4275) were from 3.6- to 57.9-fold reduced compared to wild type. The tunicamycin titers were lower inS. clavuligerus Delta bldGthan in wild type, as well. Consequently, the data presented here is the first report indicating a positive role of BldG on tunicamycin.