Retention of fatty acyl desaturase 1 (fads1) in Elopomorpha and Cyclostomata provides novel insights into the evolution of long-chain polyunsaturated fatty acid biosynthesis in vertebrates

• Published in: BMC Evolutionary Biology
• Main Authors: Lopes-Marques, Monica, Kabeya, Naoki, Qian, Yu, Ruivo, Raquel, Santos, Miguel, Venkatesh, Byrappa, Tocher, Douglas R, Castro, L Filipe C, Monroig, Oscar
• Other Authors: University of Porto, University of Tokyo, Institute of Aquaculture, orcid:0000-0002-8603-9410, orcid:0000-0001-8712-0440
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Biosynthesis; Fatty acyl desaturase; Gene duplication; Gene loss; Long-chain polyunsaturated fatty acids; Arctic; Gar’
• Online Access: http://hdl.handle.net/1893/28256; https://doi.org/10.1186/s12862-018-1271-5; http://dspace.stir.ac.uk/bitstream/1893/28256/1/LopezMarquesRetentionOfFattyAcylDesaturase.pdf

Background Provision of long-chain polyunsaturated fatty acids (LC-PUFA) in vertebrates occurs through the diet or via endogenous production from C18 precursors through consecutive elongations and desaturations. It has been postulated that the abundance of LC-PUFA in the marine environment has remarkably modulated the gene complement and function of Fads in marine teleosts. In vertebrates two fatty acyl desaturases, namely Fads1 and Fads2, encode ∆5 and ∆6 desaturases, respectively. To fully clarify the evolutionary history of LC-PUFA biosynthesis in vertebrates, we investigated the gene repertoire and function of Fads from species placed at key evolutionary nodes. Results We demonstrate that functional Fads1Δ5 and Fads2∆6 arose from a tandem gene duplication in the ancestor of vertebrates, since they are present in the Arctic lamprey. Additionally, we show that a similar condition was retained in ray-finned fish such as the Senegal bichir and spotted gar, with the identification of fads1 genes in these lineages. Functional characterisation of the isolated desaturases reveals the first case of a Fads1 enzyme with ∆5 desaturase activity in the Teleostei lineage, the Elopomorpha. In contrast, in Osteoglossomorpha genomes, while no fads1 was identified, two separate fads2 duplicates with ∆6 and ∆5 desaturase activities respectively were uncovered. Conclusions We conclude that, while the essential genetic components involved LC-PUFA biosynthesis evolved in the vertebrate ancestor, the full completion of the LC-PUFA biosynthesis pathway arose uniquely in gnathostomes.