Elongation capacity of polyunsaturated fatty acids in the annelid .

Elongation of very long-chain fatty acid (Elovl) proteins plays pivotal functions in the biosynthesis of the physiologically essential long-chain polyunsaturated fatty acids (LC-PUFA). Polychaetes have important roles in marine ecosystems, contributing not only to nutrient recycling but also exhibiting a distinctive capacity for biosynthesizing LC-PUFA. To expand our understanding of the LC-PUFA biosynthesis in polychaetes, this study conducted a thorough molecular and functional characterization of Elovl occurring in the model organism . We identify six Elovl in the genome of . The sequence and phylogenetic analyses established that four Elovl, identified as Elovl2/5, Elovl4 (two genes) and Elovl1/7, have putative functions in LC-PUFA biosynthesis. Functional characterization confirmed the roles of these elongases in LC-PUFA biosynthesis, demonstrating that possesses a varied and functionally diverse complement of Elovl that, along with the enzymatic specificities of previously characterized desaturases, enables to perform all the reactions required for the biosynthesis of the LC-PUFA. Importantly, we uncovered that one of the two Elovl4-encoding genes is remarkably long in comparison with any other animals' Elovl, which contains a C terminal KH domain unique among Elovl. The distinctive expression pattern of this protein in photoreceptors strongly suggests a central role in vision.