Genetic analysis of sulfate assimilation gene cluster of Streptomyces coelicolor A3(2)

Abstract

Aim. Streptomyces coelicolor A3(2) is the best studied species within this bacterial genus. Biosynthesis of specialized (secondary) metabolites by Streptomyces is of special interest. Primary metabolism, where all the precursors of specialized metabolites come from, is also studied in great detail. There are glaring gaps in our knowledge of sulfur metabolism in this species. We took genetic approach to probe the function of several genes within presumed sulfate assimilation gene cluster of S. coelicolor A3(2). Methods. Microbiological and genetic approaches were combined to generate mutants and to study their properties. Results. Sulfate assimilation gene cluster is structurally and functionally similar to that of phylogenetically close Corynebacterium. Most of the generated knockout strains behaved as would be expected from their molecular function inferred in silico. This confirms their involvement in sulfate uptake/conversion. Knockout of gene sco6101 (having no homologs from the other bacterial sulfate assimilation operons) impaired the growth on inorganic sulfur species and L-cysteine, pointing to its association with sulfur metabolism. Conclusions. Our study provides experimental evidence for the involvement of sco6093-sco6102 segment in sulfate assimilation, and also reveals novel gene, sco6101, essential for sulfur cycle. Further efforts are needed to elucidate the mechanism of Sco6101 action.