Biosynthesis of isoprenoid wax ester in Marinobacter hydrocarbonoclasticus DSM 8798: Identification and characterization of isoprenoid CoA-synthetase and wax ester synthases

Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 1479 Gortner Avenue, St. Paul, MN 55108

^* To whom correspondence should be addressed. Email: schmi232{at}umn.edu.

	Abstract

Marinobacter hydrocarbonoclasticus DSM 8798 has been reported to synthesize isoprenoid wax ester storage compounds when grown on phytol as the sole carbon source under limiting nitrogen and/or phosphorous conditions. We hypothesized that isoprenoid wax ester synthesis involves (i) activation of an isoprenoid fatty acid by a CoA synthetase and (ii) ester bond formation between an isoprenoid alcohol and isoprenoyl-CoA catalyzed, most likely, by an isoprenoid wax ester synthase similar to an acyl wax ester synthase (WS/DGAT) recently described from Acinetobacter ADP1. We used the recently released rough draft genome sequence of a closely related strain, M. aquaeolei VT8, to search for WS/DGAT and acyl-CoA synthetase candidate genes. The sequence information from putative WS/DGAT and acyl-CoA synthetase genes identified in this strain was used to clone homologues from the isoprenoid wax ester synthesizing Marinobacter strain. The activities of the recombinant enzymes were characterized and two new isoprenoid wax ester synthases capable of synthesizing isoprenoid ester and acyl/isoprenoid hybrid ester in vitro were identified along with an isoprenoid specific CoA-synthetase. One of the Marinobacter wax ester synthases displays several orders of magnitude higher activity towards acyl substrates than any previously characterized acyl-WS and may reflect adaptations to available carbon sources in their environments.