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A phosphopantetheinyl transferase (PPTase) gene (pfaE), cloned from the docosahexaenoic acid (DHA)-producing bacterium Moritella marina strain MP-1, has an open reading frame of 861 bp encoding a 287-amino acid protein. When the pfaE gene was expressed with pfaA-D, which are four out of five essential genes for biosynthesis of eicosapentaenoic acid (EPA) derived from Shewanella pneumatophori SCRC-2738 in Escherichia coli, the recombinant produced 12% EPA of total fatty acids. This suggests that pfaE encodes a PPTase required for producing n À 3 polyunsaturated fatty acids, which is probably involved in the synthesis of DHA in M. marina strain MP-1.

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The colony-forming ability of Escherichia coli genetically engineered to produce eicosapentaenoic acid (EPA) grown in 3 mM hydrogen peroxide (H 2 O 2 ) was similar to that of untreated cells. It was rapidly lost in the absence of EPA. H 2 O 2 -induced protein carbonylation was enhanced in cells lacking EPA. The fatty acid composition of the transformants was unaffected by H 2 O 2 treatment, but the amount of fatty acids decreased in cultures of cells lacking EPA and increased in cultures of cells producing EPA, suggesting that cellular EPA is stable in the presence of H 2 O 2 in vivo and may protect cells directly against oxidative damage. We discuss the possible role of EPA in partially blocking the penetration of H 2 O 2 into cells through membranes containing EPA.

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