Conversion of o-succinylbenzoate to dihydroxynaphthoate by extracts of Micrococcus luteus

Abstract

Cell-free extracts were prepared from either freshly grown or spray-dried cells of M. luteus ATCC 4698 by treatment with DNase and lysozyme. These extracts converted o-succinylbenzoic acid (OSB) to 1,4-dihydroxy-2-naphthoic acid (DHNA) as shown by spectrophotofluorometric and radioactivity assays. The conversion required the presence of ATP, CoA and Mg2+. Using [2-14C]OSB, the simultaneous production of the spirodilactone form of OSB was also demonstrated. The 2 products formed from OSB were further characterized by gas chromatography combined with mass spectrometry. The production of the spirodilactone was suppressed by the addition of a preparation of the enzyme DHNA synthase obtained from Mycobacterium phlei. This enzyme catalyzes the conversion of a CoA derivative of OSB to DHNA. On mild acid treatment, the M. luteus extracts retained the ability to produce spirodilactone but lost the ability to form DHNA. Apparently, an OSB-CoA derivative is an intermediate in the conversion of OSB to DHNA by M. luteus and 2 enzymes are involved, one to form the OSB-CoA derivative and the second to carry out a cyclization reaction.