Our work with almond peptide N-glycosidase A made us interested also in the α1,3/4-fucosidase which is used as a specific reagent for glycoconjugate analysis. The enzyme was purified to presumed homogeneity by a series of chromatographic steps including dye affinity and fast-performance anion exchange chromatography. The 63 kDa band was analyzed by tandem mass spectrometry which yielded several partial sequences. A homology search retrieved the hypothetical protein Q8GW72 from Arabidopsis thaliana. This protein has recently been described as being specific for α1,2-linkages. However, cDNA cloning and expression in Pichia pastoris of the A. thaliana fucosidase showed that it hydrolyzed fucose in 3- and 4-linkage to GlcNAc in Lewis determinants whereas neither 2-linked fucose nor fucose in 3-linkage to the innermost GlcNAc residue were attacked. This first cloning of a plant α1,3/4-fucosidase also confirmed the identity of the purified almond enzyme and thus settles the notorious uncertainty about its molecular mass. The α1,3/4-fucosidase from Arabidopsis exhibited striking sequence similarity with an enzyme of similar substrate specificity from Streptomyces sp. (Q9Z4I9) and with putative proteins from rice.
Bibliographical noteA corrigendum for this article exists in Phytochemistry, vol. 67, issue 13, p. 1399. DOI: 10.1016/j.phytochem.2006.04.022
- Lewis a
- Plant glycosidase