Identification of a novel group of putative Arabidopsis thaliana β-(1,3)-galactosyltransferases

• Published in: Plant molecular biology Vol. 68; no. 1-2; pp. 43 - 59
• Main Authors: Qu, Yongmei, Egelund, Jack, Gilson, Paul R, Houghton, Fiona, Gleeson, Paul A, Schultz, Carolyn J, Bacic, Antony
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.09.2008; Springer Netherlands
• Subjects: Amino Acid Sequence; Animals; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - classification; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biochemistry; Biomedical and Life Sciences; Cercopithecus aethiops; COS Cells; Fluorescent Antibody Technique; Galactosyltransferases - classification; Galactosyltransferases - genetics; Galactosyltransferases - metabolism; Golgi Apparatus - metabolism; Immunoblotting; Life Sciences; Molecular Sequence Data; Mucoproteins - classification; Mucoproteins - genetics; Mucoproteins - metabolism; Oligonucleotide Array Sequence Analysis; Phylogeny; Plant Pathology; Plant Proteins - classification; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Sciences; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; CAZy-database; Galactosyltransferase; Arabinogalactan-protein; Golgi; Glycosyltransferase
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-008-9351-3

To begin biochemical and molecular studies on the biosynthesis of the type II arabinogalactan chains on arabinogalactan-proteins (AGPs), we adopted a bioinformatic approach to identify and systematically characterise the putative galactosyltransferases (GalTs) responsible for synthesizing the β-(1,3)-Gal linkage from CAZy GT-family-31 from Arabidopsis thaliana. These analyses confirmed that 20 members of the GT-31 family contained domains/motifs typical of biochemically characterised β-(1,3)-GTs from mammalian systems. Microarray data confirm that members of this family are expressed throughout all tissues making them likely candidates for the assembly of the ubiquitously found AGPs. One member, At1g77810, was selected for further analysis including location studies that confirmed its presence in the Golgi and preliminary enzyme substrate specificity studies that demonstrated β-(1,3)-GalT activity. This bioinformatic/molecular study of CAZy GT-family-31 was validated by the recent report of Strasser et al. (Plant Cell 19:2278-2292, 2007) that another member of this family (At1g26810; GALT1) encodes a β-(1,3)-GalT involved in the biosynthesis of the Lewis a epitope of N-glycans in Arabidopsis thaliana.