Affiliation:
1. Department of Microbiology, Washington State University, Pullman, Washington 99164-4233,1and
2. USDA Agricultural Research Service, Root Disease and Biological Control Research Unit, Washington State University, Pullman, Washington 99164-64302
Abstract
ABSTRACT
The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) is produced by many strains of fluorescent
Pseudomonas
spp. with biocontrol activity against soilborne fungal plant pathogens. Genes required for 2,4-DAPG synthesis by
P. fluorescens
Q2-87 are encoded by a 6.5-kb fragment of genomic DNA that can transfer production of 2,4-DAPG to 2,4-DAPG-nonproducing recipient
Pseudomonas
strains. In this study the nucleotide sequence was determined for the 6.5-kb fragment and flanking regions of genomic DNA from strain Q2-87. Six open reading frames were identified, four of which (
phlACBD
) comprise an operon that includes a set of three genes (
phlACB
) conserved between eubacteria and archaebacteria and a gene (
phlD
) encoding a polyketide synthase with homology to chalcone and stilbene synthases from plants. The biosynthetic operon is flanked on either side by
phlE
and
phlF
, which code respectively for putative efflux and regulatory (repressor) proteins. Expression in
Escherichia coli
of
phlA
,
phlC
,
phlB
, and
phlD
, individually or in combination, identified a novel polyketide biosynthetic pathway in which PhlD is responsible for the production of monoacetylphloroglucinol (MAPG). PhlA, PhlC, and PhlB are necessary to convert MAPG to 2,4-DAPG, and they also may function in the synthesis of MAPG.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
306 articles.
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