title: A fatty acyl desaturase (fads2) with dual Δ6 and Δ5 activities from the freshwater carnivorous striped snakehead Channa striata.
abstract: There is a lack of understanding on how the environment and trophic niche affect the capability of long-chain polyunsaturated fatty acids (LC-PUFA) in freshwater carnivorous teleost. In this present study, we isolated and functionally characterised a fatty acyl desaturase (Fads) from the striped snakehead Channa striata. Sequence comparison and phylogenetic analysis suggested a Fads2 protein that is closely related to previously characterised Fads2 proteins from freshwater carnivorous and marine herbivorous fish species. We further demonstrated the capacity of Δ6 and Δ5 desaturation activities for this particular desaturase, with highest activities towards the conversion of omega-3 (n-3) polyunsaturated fatty acids (PUFA). Low Δ4 desaturation activity was also detected, although the significance of this at a physiological level remains to be studied. The expression of this striped snakehead Δ6/Δ5 fads2 gene was highest in brain, followed by liver and intestine. In liver, diet fortified with high LC-PUFA concentration impeded the expression of Δ6/Δ5 fads2 gene compared to vegetable oil (VO) based diets. The discovery of Δ6/Δ5 Fads2 desaturase here complements the previous discovery of a Δ4 Fads2 desaturase and an Elovl5 elongase, lending proof to the existence of all the required enzymatic machinery to biosynthesise LC-PUFA from C18 PUFA in a freshwater carnivorous species.
authors.affiliation: Centre for Chemical Biology, Universiti Sains Malaysia, Sains@USM, Blok B No. 10, Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang, Malaysia.
authors.forename: Meng-Kiat
authors.initials: MK
authors.lastname: Kuah
authors.affiliation: Centre for Marine and Coastal Studies, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.
authors.forename: Annette
authors.initials: A
authors.lastname: Jaya-Ram
authors.affiliation: Centre for Chemical Biology, Universiti Sains Malaysia, Sains@USM, Blok B No. 10, Persiaran Bukit Jambul, 11900 Bayan Lepas, Penang, Malaysia; Centre for Marine and Coastal Studies, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia; School of Biological Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia. Electronic address: alex@usm.my.
authors.forename: Alexander Chong
authors.initials: AC
authors.lastname: Shu-Chien
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D000090943:Delta-5 Fatty Acid Desaturase; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000235:genetics* / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage / Q000378:metabolism; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D050602:Linoleoyl-CoA Desaturase / Q000235:genetics / Q000378:metabolism; D010473:Perciformes / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
chemical_list: D000090943:Delta-5 Fatty Acid Desaturase; D004042:Dietary Fats, Unsaturated; D005231:Fatty Acids, Unsaturated; D029941:Fish Proteins; D044943:Fatty Acid Desaturases; D050602:Linoleoyl-CoA Desaturase