Menaquinone biosynthesis: conversion of o-succinylbenzoic acid to 1,4-dihydroxy-2-naphthoic acid and menaquinones by Escherichia coli extracts.

Two intermediates in the biosynthetic pathway to bacterial menaquinones are o-succinylbenzoic acid and 1,4-dihydroxy-2-naphthoic acid. Cell-free extracts have been prepared from Escherichia coli which catalyze the conversion of labeled o-succinylbenzoic acid to the naphthoic acid and also to menaquinones. The naphthoate synthetase has been partially purified and found to require coenzyme A and ATP. The synthetase has an approximate molecular weight of 45 000. The conversion of o-succinylbenzoic acid to menaquinones is stimulated by the presence of farnesyl pyrophosphate. The major menaquinone produced is then MK-3 with the farnesyl side chain.