Molecular cloning and functional analysis of a Δ12-fatty acid desaturase from the Antarctic microalga Chlamydomonas sp. ICE-L

Chlamydomonas sp. ICE-L, which can thrive in extreme environments of the Antarctic, could represent a promising alternative for polyunsaturated fatty acid (PUFA) production. A new Δ12-fatty acid desaturase (FAD)-encoding gene (Δ12CiFAD), 1269 bp in size, was cloned from Chlamydomonas sp. ICE-L. Bioinformatics analysis showed that Δ12CiFAD-encoded protein was homologous to known FADs with conserved histidine motifs, and localized to the chloroplast. Functional analysis of Δ12CiFAD indicated that recombinant Synechococcus 6803 expressing Δ12CiFAD could accumulate C18:2, whereas recombinant Saccharomyces cerevisiae expressing this enzyme could not accumulate C18:2 or any other new fatty acids. These results indicate that Δ12CiFAD is a functional enzyme in the chloroplast that can adjust Chlamydomonas sp. ICE-L cell membrane fluidity to adapt to Antarctic extreme low-temperature environments, which give us insights into the frigostable and cold-resistant mechanisms of hypothermic organisms.