Identification of a novel group of putative Arabidopsis thaliana beta-(1,3)-galactosyltransferases.
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 beta-(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 beta-(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 beta-(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 beta-(1,3)-GalT involved in the biosynthesis of the Lewis a epitope of N-glycans in Arabidopsis thaliana.
Plant Cell Biology Research Centre, School of Botany, The University of Melbourne, Melbourne, VIC, Australia.
Yongmei
Y
Qu
Jack
J
Egelund
Paul R
PR
Gilson
Fiona
F
Houghton
Paul A
PA
Gleeson
Carolyn J
CJ
Schultz
Antony
A
Bacic
D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D005455:Fluorescent Antibody Technique; D005700:Galactosyltransferases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D009088:Mucoproteins; D010940:Plant Proteins; C006619:arabinogalactan proteins; D005700:Galactosyltransferases