| Gymnodinium breve is responsible for toxic blooms causing epizootics and, in humans, neurotoxic shellfish poisoning. Toxicity is from a family of polyketides known as brevetoxins. Proposed biosynthetic mechanisms of brevetoxin production are analogous to fatty acid biosynthesis. As part of an investigation of brevetoxin production, the fatty acid synthase from Gymnodinium breve was characterized. Cell free extracts of G. breve incorporated [3H]-acetate and [3H]-acetyl-CoA into palmitate with lesser incorporation into stearate, myristate, and laurate. Fatty acid synthase activity was associated with the chloroplast, appeared to be composed of membrane-associated and soluble components, and was not completely inhibited by cerulenin. These results suggests that G. breve possesses a Type II fatty acid synthase similar in organization to those found in other photosynthetic organisms. Isolation of the enzymes, on both an enzymatic and genomic level, were hindered by low amounts G. breve cells and bacteria present within the cultures. |
