Research On The Function Of PhoR-phoP Two-Component System In Streptomyces Chattanoogensis

PhoR-phoP two-component system is discovered in most bacteria.lt is involoved in the uptake and utilization of inorganic phosphate in bacteria.The biosynthesis of the antifungal pimaricin in Streptomyces chattanoogensis is very sensitive to phosphate regulation. Concentrations of inorganic phosphate above2mM drastically reduced natamycin production. The phoR-phoP cluster of S. chattanoogensis encoding two-component Pho system was cloned and characterized. PhoR showed all of the characteristics of the membrane-bound sensor proteins, whereas PhoP is a member of the DNA-binding OmpR family. Binding of the response regulator PhoP to the consensus PHO boxes in thephoU-phoRP intergenic promoter region was observed by EMSA. Several genes which may be regulated by PhoP were discovered in Streptomyces chattanoogensis genome. And the regulation of PhoP on the gene manB was confirmed.A phoP deletion mutant and a phoR-phoP deletion mutant were obtained by PCR-targeting strategy. Production of natamycin in these two mutants increased up to70%in complex yeast extract-malt extract (YEME) medium and showed reduced sensitivity to phosphate control.In YSG medium, the production of natamycin is3.791g/1, which is80%higher than the wild type L10.However, no consensus PHO boxes were found in the promoter regions of any of the pim genes, suggesting that phosphate control of these genes is mediated indirectly by PhoR-PhoP involving modification of pathwayspecific regulators.