The transcriptional regulator PhlH modulates 2,4-diacetylphloroglucinol biosynthesis in response to the biosynthetic intermediate and end product.

The transcriptional regulator PhlH modulates 2,4-diacetylphloroglucinol biosynthesis in response to the biosynthetic intermediate and end product. Appl Environ Microbiol. 2017 Aug 18;: Authors: Yan X, Yang R, Zhao RX, Han JT, Jia WJ, Li DY, Wang Y, Zhang N, Wu Y, Zhang LQ, He YX Abstract Certain strains of biocontrol Pseudomonas fluorescens produce the secondary metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) to antagonize the soil-borne phytopathogens in the rhizosphere. The gene cluster responsible for the biosynthesis of 2,4-DAPG is named phlACBDEFGH and it is still unclear how the pathway-specific regulator phlH within this gene cluster regulates the metabolism of 2,4-DAPG. Here, we found that PhlH in Pseudomonas fluorescens strain 2P24 represses the expression of the phlG gene encoding the 2,4-DAPG hydrolase by binding to a sequence motif overlapping with the -35 site recognized by σ(70) factors. Through biochemical screening of PhlH ligands we identified the end product 2,4-DAPG and its biosynthetic intermediate monoacetylphloroglucinol (MAPG) can act as signaling molecules to modulate the binding of PhlH to the target sequence and activate the expression of phlG Comparison of 2,4-DAPG production between the ΔphlH, ΔphlG and ΔphlHG mutants confirmed that phlH and phlG impose negative feedback regulation over 2,4-DAPG biosynthesis. It was further demonstrated that the 2,4-DAPG degradation catalyzed by PhlG plays an insignif...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research