Phosphate and carbon source regulation of two PhoP-dependent glycerophosphodiester phosphodiesterase genes of Streptomyces coelicolor

Abstract

Glycerophosphodiesters are formed by deacylation of phospholipids.Streptomyces coelicolorand other soil-dwelling actinomycetes utilize glycerophosphodiesters as phosphate and carbon sources by the action of glycerophosphodiester phosphodiesterases (GDPDs). Seven genes encoding putative GDPDs occur in theS. coelicolorgenome. Two of these genes,glpQ1andglpQ2, encoding extracellular GDPDs, showed a PhoP-dependent upregulated profile in response to phosphate shiftdown. Expression studies using theluxABgenes as reporter confirmed the PhoP dependence of bothglpQ1andglpQ2. Footprinting analyses with pure GST-PhoP of theglpQ1promoter revealed four protected direct repeat units (DRu). PhoP binding affinity to theglpQ2promoter was lower and revealed a protected region containing five DRu. As expected forphoregulon genes, inorganic phosphate, and also glycerol 3-phosphate, inhibited the expression from bothglpQ1andglpQ2. The expression ofglpQ1was also repressed by serine and inositol but expression ofglpQ2was not. In contrast, glucose, fructose and glycerol increased expression ofglpQ2but not that ofglpQ1. In summary, our results suggest an interaction of phosphate control mediated by PhoP and carbon source regulation of theglpQ1andglpQ2genes involving complex operator structures.