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Identification and characterization of new ?-17 fatty acid desaturases.

ABSTRACT: ?-3 fatty acid desaturase is a key enzyme for the biosynthesis of ?-3 polyunsaturated fatty acids via the oxidative desaturase/elongase pathways. Here we report the identification of three ?-3 desaturases from oomycetes, Pythium aphanidermatum, Phytophthora sojae, and Phytophthora ramorum. These new ?-3 desaturases share 55 % identity at the amino acid level with the known ?-17 desaturase of Saprolegnia diclina, and about 31 % identity with the bifunctional ?-12/?-15 desaturase of Fusarium monoliforme. The three enzymes were expressed in either wild-type or codon optimized form in an engineered arachidonic acid producing strain of Yarrowia lipolytica to study their activity and substrate specificity. All three were able to convert the ?-6 arachidonic acid to the ?-3 eicosapentanoic acid, with a substrate conversion efficiency of 54-65 %. These enzymes have a broad ?-6 fatty acid substrate spectrum, including both C18 and C20 ?-6 fatty acids although they prefer the C20 substrates, and have strong ?-17 desaturase activity but weaker ?-15 desaturase activity. Thus, they belong to the ?-17 desaturase class. Unlike the previously identified bifunctional ?-12/?-15 desaturase from F. monoliforme, they lack ?-12 desaturase activity. The newly identified ?-17 desaturases could use fatty acids in both acyl-CoA and phospholipid fraction as substrates. The identification of these ?-17 desaturases provides a set of powerful new tools for genetic engineering of microbes and plants to produce ?-3 fatty acids, such as eicosapentanoic acid and docosahexanoic acid, at high levels.

SUBMITTER: Xue Z

PROVIDER: S-EPMC3570762 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Acinetobacter baumannii Fatty Acid Desaturases Facilitate Survival in Distinct Environments

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