51. Identification and evolution of a plant cell wall specific glycoprotein glycosyl transferase, ExAD.
- Author
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Møller SR, Yi X, Velásquez SM, Gille S, Hansen PLM, Poulsen CP, Olsen CE, Rejzek M, Parsons H, Yang Z, Wandall HH, Clausen H, Field RA, Pauly M, Estevez JM, Harholt J, Ulvskov P, and Petersen BL
- Subjects
- Arabidopsis enzymology, Arabidopsis genetics, Arabidopsis Proteins genetics, Arabidopsis Proteins metabolism, Arabinose metabolism, Cell Wall enzymology, Cell Wall genetics, DNA, Bacterial genetics, DNA, Bacterial pharmacology, Evolution, Molecular, Gene Knockout Techniques, Glycosylation, Xylosidases genetics, Xylosidases metabolism, Arabidopsis growth & development, Hexosyltransferases genetics, Hexosyltransferases metabolism, Mutation, Plant Roots anatomy & histology
- Abstract
Extensins are plant cell wall glycoproteins that act as scaffolds for the deposition of the main wall carbohydrate polymers, which are interlocked into the supramolecular wall structure through intra- and inter-molecular iso-di-tyrosine crosslinks within the extensin backbone. In the conserved canonical extensin repeat, Ser-Hyp
4 , serine and the consecutive C4-hydroxyprolines (Hyps) are substituted with an α-galactose and 1-5 β- or α-linked arabinofuranoses (Arafs), respectively. These modifications are required for correct extended structure and function of the extensin network. Here, we identified a single Arabidopsis thaliana gene, At3g57630, in clade E of the inverting Glycosyltransferase family GT47 as a candidate for the transfer of Araf to Hyp-arabinofuranotriose (Hyp-β1,4Araf-β1,2Araf-β1,2Araf) side chains in an α-linkage, to yield Hyp-Araf4 which is exclusively found in extensins. T-DNA knock-out mutants of At3g57630 showed a truncated root hair phenotype, as seen for mutants of all hitherto characterized extensin glycosylation enzymes; both root hair and glycan phenotypes were restored upon reintroduction of At3g57630. At3g57630 was named Extensin Arabinose Deficient transferase, ExAD, accordingly. The occurrence of ExAD orthologs within the Viridiplantae along with its' product, Hyp-Araf4 , point to ExAD being an evolutionary hallmark of terrestrial plants and charophyte green algae.- Published
- 2017
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