alpha-L-fucosyltransferases from radish primary roots

Area of Science:

• Plant Biochemistry
• Enzymology
• Glycobiology

Background:

• Alpha-L-fucosyltransferases play crucial roles in glycosylation processes.
• Understanding enzyme specificity and localization is key to elucidating plant cell wall biosynthesis.

Purpose of the Study:

• To identify and characterize a novel alpha-L-fucosyltransferase in radish (Raphanus sativus L.).
• To investigate the substrate specificity and expression patterns of this enzyme.

Main Methods:

• Enzyme activity was measured using a fluorometric assay with a synthetic trisaccharide acceptor (AraGalGal-PA).
• Radiolabeling and chemical/enzymatic analyses confirmed L-fucose attachment and linkage.
• Microsomal and Golgi membrane fractions were isolated for enzyme localization studies.

Main Results:

• A novel alpha-L-fucosyltransferase was identified in radish root microsomes, transferring L-fucose to the O-2 of L-arabinofuranosyl residues.
• The enzyme exhibits optimal activity at pH 6.8 and requires specific detergent and Mn2+ concentrations.
• This L-arabinofuranoside-specific enzyme shows development- and organ-specific expression in roots.
• A distinct L-fucosyltransferase activity towards tamarind xyloglucan was found in various organs.
• Two distinct alpha-L-fucosyltransferases were localized to Golgi membranes in primary roots, but absent in hypocotyl Golgi membranes.

Conclusions:

• A novel L-arabinofuranoside alpha-L-fucosyltransferase is present in radish roots, suggesting a specific role in root glycosylation.
• Differential localization and expression of fucosyltransferases indicate distinct roles in polysaccharide synthesis across different radish organs.