ABSTRACT
Pyrrolnitrin is a secondary metabolite derived from tryptophan and has strong antifungal activity. Recently we described four genes,
prnABCD
, from
Pseudomonas fluorescens
that encode the biosynthesis of pyrrolnitrin. In the work presented here, we describe the function of each
prn
gene product. The four genes encode proteins identical in size and serology to proteins present in wild-type
Pseudomonas fluorescens
, but absent from a mutant from which the entire
prn
gene region had been deleted. The
prnA
gene product catalyzes the chlorination of
l
-tryptophan to form 7-chloro-
l
-tryptophan. The
prnB
gene product catalyzes a ring rearrangement and decarboxylation to convert 7-chloro-
l
-tryptophan to monodechloroaminopyrrolnitrin. The
prnC
gene product chlorinates monodechloroaminopyrrolnitrin at the 3 position to form aminopyrrolnitrin. The
prnD
gene product catalyzes the oxidation of the amino group of aminopyrrolnitrin to a nitro group to form pyrrolnitrin. The organization of the
prn
genes in the operon is identical to the order of the reactions in the biosynthetic pathway.
摘要
吡咯烷酮是一种从色氨酸中提取的次级代谢产物,具有很强的抗真菌活性。最近,我们描述了四个基因、
prnABCD
和
荧光假单胞菌
这四个基因编码吡咯烷酮的生物合成。在本文介绍的工作中,我们描述了每个
prn
基因产物的功能。这四个基因编码的蛋白质在大小和血清学上与野生型荧光假单胞菌中的蛋白质相同。
荧光假单胞菌
荧光假单胞菌中存在,但在一个突变体中却不存在。
prn
基因区域被删除的突变体中却没有这种蛋白。其中
prnA
基因产物可催化
l
色氨酸氯化形成 7-氯-l-色氨酸。
l
-色氨酸。该
prnB
基因产物催化环的重排和脱羧作用,将 7-chloro-l -色氨酸转化为 7-chloro-l -色氨酸。
l
-色氨酸转化为单去氯氨基吡咯烷酮。prnC基因
prnC
基因产物在 3 位氯化单去氯氨基吡咯烷酮,形成氨基吡咯烷酮。而
prnD
基因产物催化氨基吡咯硝林的氨基氧化成硝基,形成吡咯硝林。prnD基因的组织结构
prn
基因在操作子中的排列顺序与生物合成途径中的反应顺序相同。