Galactosyltransferases from Arabidopsis thaliana in the biosynthesis of type II arabinogalactan: molecular interaction enhances enzyme activity

BMC Plant Biology

Research Article

György Vereb¹  Naomi Geshi²  Alexander Schulz²  Christian Peter Poulsen²  Adiphol Dilokpimol³  Satoshi Kaneko⁴ 

[1] Department of Biophysics and Cell Biology, and MTA-DE Cell Biology and Signaling Research Group, University of Debrecen, Debrecen, Hungary;Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871, Frederiksberg, C, Denmark;Department of Plant and Environmental Sciences, Thorvaldsensvej 40, 1871, Frederiksberg, C, Denmark;Fungal Physiology, CBS-KNAW, Fungal Biodiversity Center, Uppsalalaan 8, 3584, Utrecht, CT, The Netherlands;Food Biotechnology Division, National Food Research Institute, 2-1-12 Kannondai, 305-8642, Tsukuba, Ibaraki, Japan;

关键词: Arabidopsis thaliana;    Arabinogalactan protein;    Galactosyltransferase;    O;    Golgi apparatus;    Protein-protein interaction;    FRET;    Plant cell wall;   

DOI  :  10.1186/1471-2229-14-90

 received in 2013-11-13, accepted in 2014-03-25,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundArabinogalactan proteins are abundant proteoglycans present on cell surfaces of plants and involved in many cellular processes, including somatic embryogenesis, cell-cell communication and cell elongation. Arabinogalactan proteins consist mainly of glycan, which is synthesized by post-translational modification of proteins in the secretory pathway. Importance of the variations in the glycan moiety of arabinogalactan proteins for their functions has been implicated, but its biosynthetic process is poorly understood.ResultsWe have identified a novel enzyme in the biosynthesis of the glycan moiety of arabinogalactan proteins. The At1g08280 (AtGALT29A) from Arabidopsis thaliana encodes a putative glycosyltransferase (GT), which belongs to the Carbohydrate Active Enzyme family GT29. AtGALT29A co-expresses with other arabinogalactan GTs, AtGALT31A and AtGLCAT14A. The recombinant AtGALT29A expressed in Nicotiana benthamiana demonstrated a galactosyltransferase activity, transferring galactose from UDP-galactose to a mixture of various oligosaccharides derived from arabinogalactan proteins. The galactose-incorporated products were analyzed using structure-specific hydrolases indicating that the recombinant AtGALT29A possesses β-1,6-galactosyltransferase activity, elongating β-1,6-galactan side chains and forming 6-Gal branches on the β-1,3-galactan main chain of arabinogalactan proteins. The fluorescence tagged AtGALT29A expressed in N. benthamiana was localized to Golgi stacks where it interacted with AtGALT31A as indicated by Förster resonance energy transfer. Biochemically, the enzyme complex containing AtGALT31A and AtGALT29A could be co-immunoprecipitated and the isolated protein complex exhibited increased level of β-1,6-galactosyltransferase activities compared to AtGALT29A alone.ConclusionsAtGALT29A is a β-1,6-galactosyltransferase and can interact with AtGALT31A. The complex can work cooperatively to enhance the activities of adding galactose residues 6-linked to β-1,6-galactan and to β-1,3-galactan. The results provide new knowledge of the glycosylation process of arabinogalactan proteins and the functional significance of protein-protein interactions among O-glycosylation enzymes.

【 授权许可】

Unknown   
© Dilokpimol et al.; licensee BioMed Central Ltd. 2014. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.