Identification and expression of mammalian long‐chain PUFA elongation enzymes

Abstract

In mammalian cells, Sprecher has proposed that the synthesis of long-chain PUFA from the 20-carbon substrates involves two consecutive elongation steps, a delta6-desaturation step followed by retroconversion (Sprecher, H., Biochim. Biophys. Acta 1486, 219-231, 2000). We searched the database using the translated sequence of human elongase ELOVL5, whose encoded enzyme elongates monounsaturated and polyunsaturated FA, as a query to identify the enzyme(s) involved in elongation of very long chain PUFA. The database search led to the isolation of two cDNA clones from human and mouse. These clones displayed deduced amino acid sequences that had 56.4 and 58% identity, respectively, to that of ELOVL5. The open reading frame of the human clone (ELOVL2) encodes a 296-amino acid peptide, whereas the mouse clone (Elovl2) encodes a 292-amino acid peptide. Expression of these open reading frames in baker's yeast, Saccharomyces cerevisiae, demonstrated that the encoded proteins were involved in the elongation of both 20- and 22-carbon long-chain PUFA, as determined by the conversion of 20:4n-6 to 22:4n-6, 22:4n-6 to 24:4n-6, 20:5n-3 to 22:5n-3, and 22:5n-3 to 24:5n-3. The elongation activity of the mouse Elovl2 was further demonstrated in the transformed mouse L cells incubated with long-chain (C20- and C22-carbon) n-6 and n-3 PUFA substrates by the significant increase in the levels of 24:4n-6 and 24:5n-3, respectively. This report demonstrates the isolation and identification of two mammalian genes that encode very long chain PUFA specific elongation enzymes in the Sprecher pathway for DHA synthesis.

Obesity resistance and deregulation of lipogenesis in Δ6‐fatty acid desaturase ( FADS 2) deficiency

“…ELOVL2 in nd-, AA-and DHA À/À liver is essential for the synthesis of x6-very long chain PUFAs (VLCFA) [18]. 18:2 and c-18:3 are the preferred substrates of ELOVL5 [19]. Elovl3 expression was downregulated and thereby the synthesis of saturated VLCFA and recruitment of saturated triglycerides to BAT [20], but elovl6, which encodes the elongase of saturated C12-C16 fatty acids and also correlates positively with the severity of hepatosteatosis was overexpressed.…”

Zebrafish cDNA Encoding Multifunctional Fatty Acid Elongase Involved in Production of Eicosapentaenoic (20:5n-3) and Docosahexaenoic (22:6n-3) Acids

“…and C 22 PUFA (Leonard et al, 2002). Neither the elovl2 or ELOVL2 clones showed any significant activity towards saturated or monounsaturated fatty acids (Leonard et al, 2002).…”

“…Very recently, two mammalian genes have been cloned and characterized, a further human elongase (ELOVL2) and a mouse elongase (elovl2), both of which were able to elongate 22:5n-3 and 22:4n-6 to 24:5n-3 and 24:4n-6, respectively (Leonard et al, 2002). Like the zebrafish enzyme, the mouse elovl2 clone was also able to elongate C 18 and C 20 PUFA, whereas the human ELOVL2 clone was only active towards C 20…”

ELOVL2 gene polymorphisms are associated with increases in plasma eicosapentaenoic and docosahexaenoic acid proportions after fish oil supplement

“…Members of the elongation-of-very-long-chain-fatty-acids (ELOVL) gene family encode elongases specific for substrate chain length and degree of unsaturation. Human elongase-5 (ELOVL5) elongates C 18 and C 20 PUFA (Leonard et al 2000) and elongase-2 (ELOVL2) is active with C 20 and C 22 PUFA (Leonard et al 2002). In the n-3 LC-PUFA biosynthetic sequence, the delta-5 desaturase FADS1 catalyses the formation of EPA.…”