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.
摘要
从铜绿假单胞菌中克隆了两个七基因酚嗪生物合成位点
铜绿假单胞菌
PAO1。这些操作子被命名为
phzA1B1C1D1E1F1G1
和
phzA2B2C2D2E2F2G2
与以前研究过的荧光假单胞菌中的酚嗪生物合成操作子同源。
荧光假单胞菌
和
假单胞菌的酚嗪生物合成操作子。
.对不产酚嗪的荧光假单胞菌菌株进行的功能研究表明,铜绿假单胞菌的每个生物合成操作子都与酚嗪生物合成操作子同源。
铜绿假单胞菌
足以生产单一化合物酚嗪-1-羧酸(PCA)。在铜绿假单胞菌中,酚嗪-1-羧酸(PCA)随后转化为芘花青素的过程是由
铜绿微囊藻
由两个新型酚嗪修饰基因介导、
phzM
和
phzS
分别编码推定的酚嗪特异性甲基转移酶和含黄素单氧化酶。表达
phzS
单独在
大肠杆菌
或酶的情况下,不产生焦花青素的
荧光团
导致 PCA 转化为 1-羟基吩嗪。
铜绿菌
具有插入失活的
phzM
或
phzS
会出现缺乏脓青素的表型。第三个酚嗪修饰基因
phzH
在
假单胞菌中的同源基因
铜绿假单胞菌中也发现了第三个酚嗪修饰基因 phzH,该基因在氯葡萄假单胞菌中也有同源物。
铜绿假单胞菌
PAO1。我们的研究结果表明,在铜绿假单胞菌 PAO1 中存在着一个复杂的芘花青素生物合成途径。
铜绿菌
由负责合成 PCA 的两个核心基因位点和编码参与将 PCA 转化为芘花青素、1-羟基吩嗪和吩嗪-1-甲酰胺的独特酶的另外三个基因组成。