Molecular Cloning and Characterization of Two Zebrafish α(1, 3)Fucosyltransferase Genes Developmentally Regulated in Embryogenesis

Abstract

Some α(1, 3)fucosylated oligosaccharides serve as counter receptors to lectin-like adhesion proteins or are expressed with temporal precision during embryogenesis, and α(1, 3)-fucosyltransferase is a key enzyme in the production of these oligosaccharides. Two α(1, 3)-fucosyltransferase genes, designated zFT1 and zFT2, were cloned from zebrafish. Sequence comparisons with other genes indicated that zFT1 and zFT2 share about 30% amino acid sequence identity with human α(1, 3)fucosyltransferases. Although the α(1, 3)fucosyltransferases cloned so far can be classified into three types-myeloid, Lewis, and leukocyte-by virtue of their amino acid sequences, phylogenetic analysis indicated that neither zFT1 nor zFT2 belongs to any of these categories. The expression of zFT1 or zFT2 in mammalian cells induces α(1, 3)fucosyltransferase activity to synthesize the Lewis x structure from pyridyl-aminated lacto-N-neotetraose; however, lacto-N-tetraose does not serve as a substrate. Reverse transcriptase-polymerase chain reaction analysis revealed that zFT1 is transcribed during a restricted period before hatching, whereas the mRNA for zFT2 was detected only after hatching.