Regulation of production of the antifungal metabolite 2,4-diacetylphloroglucinol in Pseudomonas fluorescens F113: genetic analysis of phlF as a transcriptional repressor
I. Delany et al., Regulation of production of the antifungal metabolite 2,4-diacetylphloroglucinol in Pseudomonas fluorescens F113: genetic analysis of phlF as a transcriptional repressor, MICROBIO-UK, 146, 2000, pp. 537-546
The antifungal metabolite 2,4-diacetylphloroglucinol plays a major role in
the biocontrol capabilities of Pseudomonas fluorescens. The phloroglucinol
biosynthetic locus of P. fluorescens F113 has been isolated previously, Fro
m nucleotide sequence data, a putative regulator gene (phlF) was identified
upstream and divergently transcribed from the phlACBD phloroglucinol biosy
nthetic genes. PhlF shows similarity to various transcriptional repressors
in the EMBL database and exhibits a helix-turn-helix motif in its amino aci
d sequence. phlF was cloned into an expression vector and the PhlF protein
product was purified. Gel retardation experiments demonstrated PhlF to be a
DNA-binding protein and showed that it binds to the phlA-phlF intergenic r
egion. Introduction of phlF into P. fluorescens F113 in multiple copies res
ulted in repression of phloroglucinol production in this strain, This effec
t was mediated at the transcription level since the expression of a phlorog
lucinol biosynthetic gene fusion in this background was equally repressed,
Furthermore, the inactivation of phlF results in derepression of phlorogluc
inol production in this strain.