Ketosynthetases AlpRQ affects the yield of kinamycin

Abstract:

Kinamycin gene cluster contains two ketosynthase (KS_α and KS_β) coding genes, namely alpA, alpB and alpR, alpQ, the first two are necessary for the synthesis of kinamycin, and alpR and alpQ are thought to be involved in the synthesis of other compounds.[Objective] Since alpR and alpQ are adjacent to the essential gene alpS in the kinamycin synthesis gene cluster, this study aims to identify their correlation with kinamycin biosynthesis.[Methods] The PCR-targeting multigene knockout was done on the bacterial artificial chromosome library plasmid, and the constructed library plasmid was introduced into Streptomyces albus J1074, a general Streptomyces host. The fermentation products of the mutant and the wild-type strains were detected by high performance liquid chromatography. [Results] AlpR and AlpQ had no direct effect on the synthesis of kinamycin, but the yield of kinamycin increased significantly in ΔalpRQ mutant.[Conclusion] AlpR and AlpQ are likely KS_α and KS_β for the biosynthesis of another type II polyketide compound, competing for common synthetic precursors with AlpA and AlpB. This study also demonstrates that alpR and alpQ cannot complement the function of alpA and alpB.