Monogalactosyldiacylglycerol biosynthesis by direct acyl transfer in Anabaene variabilis
The authors previously reported the direct acylation of monogalactosyldiacylglycerol (MGDG) by an enzyme in the membranes of the cyanobacterium Anabaena variabilis. The enzyme requires acyl-acyl carrier protein (acyl-ACP) as substrate, but had no other additional cofactor requirements. Palmitoyl-, stearoyl- and oleoyl-ACP were all effective substrates. The A. variabilis membranes also had a hydrolase activity which metabolized the acyl-ACP to yield free fatty acid and ACP. Possible mechanisms for the acylation reaction include either acyl exchange with existing MGDG or direct acyl transfer to a lyso-MGDG, with concomitant release of free ACP. The mechanism of this reaction has been resolved using a double labelled (/sup 14/C)acyl-(/sup 14/)ACP substrate prepared with E. coli acyl-ACP synthetase. Following incubation with the enzyme, the unreacted (/sup 14/)acyl-(/sup 14/)ACP was isolated and the (/sup 14/)acyl/(/sup 14/)ACP ratio determined. Comparison of this ratio to that of the original substrate indicated no change and eliminated acyl exchange as a possible mechanism. Therefore, the direct acylation of lyso-MGDG is the proposed mechanism for this enzyme.
- Research Organization:
- Miami Univ., Oxford, OH
- OSTI ID:
- 5725879
- Report Number(s):
- CONF-8707108-
- Journal Information:
- Plant Physiol., Suppl.; (United States), Journal Name: Plant Physiol., Suppl.; (United States) Vol. 83:4; ISSN PPYSA
- Country of Publication:
- United States
- Language:
- English
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