Identification of the blood group Lewis a determinant in the oviducal mucins of Xenopus tropicalis

Abstract

The amphibian Xenopus tropicalis appears an increasingly appealing model for both genetic and developmental biology studies, compared to the related species Xenopus laevis. Study of the glycosylation pattern of its secreted glycoproteins revealed that this species synthesizes large amounts of Lewis a epitope, whereas this motif has previously only been identified in animals within the primate lineage. The use of 1H-nuclear magnetic resonance spectroscopy enabled us to resolve the sequence of three Lewis a-bearing O-linked glycans associated with oviducal secretions, out of which one contained the novel sequence Gal(β1–3)GlcNAc(β1–6)GalNAc-ol. These structural data suggested the emergence of an α1,4-fucosyltransferase activity in animals outside the primate lineage. On this basis, the screening of a X. tropicalis GenBank database with human Lewis-fucosyltransferase sequences revealed the occurrence of a putative fucosyltransferase gene that presented an unusual acceptor motif.