Affiliation:
1. Department of Plant Pathology1 and
2. School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-42342
3. USDA-ARS Root Disease and Biological Control Research Unit, Agricultural Research Service,3 Washington State University, Pullman, Washington 99164-6430, and
Abstract
ABSTRACT
Two seven-gene phenazine biosynthetic loci were cloned from
Pseudomonas aeruginosa
PAO1. The operons, designated
phzA1B1C1D1E1F1G1
and
phzA2B2C2D2E2F2G2
, are homologous to previously studied phenazine biosynthetic operons from
Pseudomonas fluorescens
and
Pseudomonas aureofaciens
. Functional studies of phenazine-nonproducing strains of fluorescent pseudomonads indicated that each of the biosynthetic operons from
P. aeruginosa
is sufficient for production of a single compound, phenazine-1-carboxylic acid (PCA). Subsequent conversion of PCA to pyocyanin is mediated in
P. aeruginosa
by two novel phenazine-modifying genes,
phzM
and
phzS
, which encode putative phenazine-specific methyltransferase and flavin-containing monooxygenase, respectively. Expression of
phzS
alone in
Escherichia coli
or in enzymes, pyocyanin-nonproducing
P. fluorescens
resulted in conversion of PCA to 1-hydroxyphenazine.
P. aeruginosa
with insertionally inactivated
phzM
or
phzS
developed pyocyanin-deficient phenotypes. A third phenazine-modifying gene,
phzH
, which has a homologue in
Pseudomonas chlororaphis
, also was identified and was shown to control synthesis of phenazine-1-carboxamide from PCA in
P. aeruginosa
PAO1. Our results suggest that there is a complex pyocyanin biosynthetic pathway in
P. aeruginosa
consisting of two core loci responsible for synthesis of PCA and three additional genes encoding unique enzymes involved in the conversion of PCA to pyocyanin, 1-hydroxyphenazine, and phenazine-1-carboxamide.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
618 articles.
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