Abstract
BACKGROUND: Actinomycetes of the genus Streptomyces are renowned for their highly developed and diverse specialized metaboliс pathways, and there is an extensive body of data on their specific and pleiotropic levels of regulation. Much less is known about routes leading to essential metabolites in this genus. In this work, we focused on elucidating the function of the highly conserved across Streptomyces gene SCO1417 for GntR type regulator in the model strain S. coelicolor A3(2). RESULTS: Combining the results of knockout and promoter probe experiments, we show that the gene SCO1417 controls pyridoxal 5'-phosphate (PLP; vitamin B6) biosynthesis, and thus is a member of the PdxR group of the transcriptional regulators. The Sco1417 protein is a transcriptional repressor of its gene and an activator of the expression of the PLP synthase genes, SCO1523 (pdxS) and SCO1522 (pdxT). According to electrophoretic mobility shift assays, out of several tested B6 vitamers, only PLP served as a Sco1417 effector molecule. We also provide data on the location of the Sco1417 binding site within the promoter region of pdxST. CONCLUSIONS: Our work portrays for the first time an evidence-based picture of the genetic control of vitamin B6 biosynthesis in S. coelicolor M145. Given the high conservancy and synteny of pdx homologs in the other streptomycetes, we suggest that the described genetic circuit is a general feature for the entire genus.