|Masuo S, Tsuda Y, Namai T, Minakawa H, Shigemoto R, Takaya N
|Enzymatic cascade in Pseudomonas for pyrazine production from α-amino acids
| acetyltransferase; amino acid; biosynthesis; nitrogen heterocycle; pyrazine
|Pyrazines are widespread chemical compounds that include pheromones and odors. Here we describe a novel mechanism used by Pseudomonas fluorescens SBW25 to biosynthesize monocyclic pyrazines. Heterologous expression of the papABC genes that synthesize the natural α-amino acid, 4-aminophenylalanine (4APhe), together with three adjacent papDEF genes of unknown function in Escherichia coli resulted in the production of 2,5-dimethyl-3,6-bis(4-aminobenzyl)-pyrazine (DMBAP), which comprised two symmetrical aminobenzyl moieties derived from 4APhe.We found that PapD is a novel amino acid. Two molecules of C-acetyltransferase that decarboxylates and transfers acetyl residues to 4APhe to generate an α-aminoketone, spontaneously dehydration-condense to dihydro DMBAP. PapF is a novel oxidase in the amine oxidase superfamily, and it oxidized dihydro DMBAP to yield the pyrazine ring of DMBAP. These two enzymes constitute a unique mechanism for synthesizing monocyclic pyrazines and might serve as a novel strategy for the enzymatic synthesis of pyrazine derivatives from natural α-amino acids.