CDNA cloning and primary structure comparison of tauropine dehydrogenase and β-alanopine dehydrogenase from the limpet Cellana grata

Abstract

The primary structures of β-alanopine dehydrogenase (β-AlDH) and tauropine dehydrogenase (TaDH) from the limpet Cellana grata were determined by amino acid sequence analysis and complementary DNA (cDNA) cloning. β-AlDH and TaDH cDNAs comprised 1,479 nucleotides and 1,444 nucleotides, respectively, and both included an open reading frame of 1,206 nucleotides corresponding to 402 amino acids. The enzymes showed very high homology, with 96% amino acid identity. These enzymes were homologous to other marine invertebrate opine dehydrogenases (OpDHs), except TaDH of the marine sponge Halichondria japonica. The highest homologies were to alanopine dehydrogenase from Fusitriton oregonensis, being 57% for both enzymes. A phylogenetic tree constructed on the basis of marine invertebrate OpDHs and developed using a sequence distance method and neighbor-joining algorithm showed a tendency for the classification of animals from taxonomically derived evolutionary trees. Additionally, Cellana grata OpDHs belong to the same group as the Gastropoda OpDHs. This represents the first report concerning the primary structure of marine invertebrate β-AlDH, and primary structure comparisons of clearly different enzymes from the same species.