Phylogenetic analysis of Fatty Acid Desaturases reveals contrasting evolutionary clues in ciliates.

CID NICOLAS; MARIA LUZ SANCHEZ; MONTES, GUADALUPE; EUGENIA ELGUERO; B.C. NUDEL; A. D. NUSBLAT

CABA

Conferencia; International Society for Computational Biology Latin America Bioinformatics Conference; 2016

A2B2C

The Integral Membrane Diiron Enzymes (IMDE) are a class of binuclear non-heme iron proteins widely distributed among prokaryotes and eukaryotes. They are characterized by a conserved tripartite motif consisting of eight to ten histidines. Their key function is the activation of the dioxygen moiety to serve as efficient catalysts for reactions of hydroxylation, desaturation or reduction. To date most studies on IMDE were carried out in metazoan, phototrophic or parasitic organisms, whereas genome-wide analysis in heterotrophic free living protozoa, such as the Ciliophora phylum, has not been undertaken. Our genome wide approach retrieved 118 putative sequences of the IMDE type with large differences in number among the ciliates: 11 sequences in Euplotes octocarinatus, 7 in Ichthyophthirius multifiliis, 13 in Oxytricha trifallax, 18 in Stilonichia lemnae, 25 in Tetrahymena thermophila, 31 in Paramecium tetraurelia and 13 in Pseudocohnilembus persalinus. Interestingly, the analysis of the FA desaturases family showed that the spirotrichs O. trifallax and S.lemnae have no genes that encode for any of these proteins, suggesting that their lipids derive from algae like C. reinhardtii, which is used as foodstuff in cultures. Additionally the analysis of the lipid content of O. trifallax by GC?MS revealed a quantitative composition in the ratio of saturated/unsaturated fatty acids that was significantly different from the algae, thus indicating re-routing, modification and regulation of precursors not previously described.