Polymorphism of the caprine malic enzyme 1 (ME1) gene and its association with milk quality traits in Murciano–Granadina goats

Malic enzyme 1 plays a fundamental role in lipid metabolism because it yields a significant amount of the NADPH necessary for fatty acid biosynthesis. In ruminants, however, its contribution to this biochemical process seems to be less relevant than in other livestock species. In this study, we have partially sequenced the goat ME1 gene with the aim of identifying polymorphic sites. Structural analysis of the goat ME1 amino acid partial sequence evidenced the existence of two dinucleotide-binding motifs, located at positions 158 to 163 (GLGDLG) and 301 to 306 (GAGEAA), and three amino acid residues (E245, D246 and D269) involved in the binding of Mn21 and strongly conserved among mammalian species. Moreover, multiple sequence alignment allowed us to identify four single nucleotide polymorphisms at exons 5 (c.483C.T), 6 (c.667G.A), 9 (c.927C.T) and 11 (c.1200G.A). The effects of ME1 genotype on milk production and composition traits were investigated in a Murciano– Granadina goat population. None of the associations found reached statistical significance after applying Benjamini–Hochberg correction. At most, associations with uncorrected P-values below 0.01 were observed for C16:0, C18:1n-9t and total conjugated linoleic acids. These negative results reinforce the notion that ME1 plays an ancillary role in ruminant lipogenesis.