The high-affinity phosphate-binding protein PstS is accumulated under high fructose concentrations and mutation of the corresponding gene affects differentiation in Streptomyces lividans

Abstract

The secreted protein pattern ofStreptomyces lividansdepends on the carbon source present in the culture media. One protein that shows the most dramatic change is the high-affinity phosphate-binding protein PstS, which is strongly accumulated in the supernatant of liquid cultures containing high concentrations (>3 %) of certain sugars, such as fructose, galactose and mannose. The promoter region of this gene and that of itsStreptomyces coelicolorhomologue were used to drive the expression of a xylanase inS. lividansthat was accumulated in the culture supernatant when grown in the presence of fructose. PstS accumulation was dramatically increased in aS. lividanspolyphosphate kinase null mutant (Δppk) and was impaired in a deletion mutant lackingphoP, the transcriptional regulator gene of the two-componentphoR-phoPsystem that controls the Pho regulon. Deletion of thepstSgenes inS. lividansandS. coelicolorimpaired phosphate transport and accelerated differentiation and sporulation on solid media. Complementation with a single copy in aS. lividans pstSnull mutant returned phosphate transport and sporulation to levels similar to those of the wild-type strain. The present work demonstrates that carbon and phosphate metabolism are linked in the regulation of genes and that this can trigger the genetic switch towards morphogenesis.