RRC ID 48573
Author Sampedro J, Valdivia ER, Fraga P, Iglesias N, Revilla G, Zarra I.
Title Soluble and Membrane-Bound β-Glucosidases Are Involved in Trimming the Xyloglucan Backbone.
Journal Plant Physiol.
Abstract In many flowering plants, xyloglucan is a major component of primary cell walls, where it plays an important role in growth regulation. Xyloglucan can be degraded by a suite of exoglycosidases that remove specific sugars. In this work, we show that the xyloglucan backbone, formed by (1→4)-linked β-d-glucopyranosyl residues, can be attacked by two different Arabidopsis (Arabidopsis thaliana) β-glucosidases from glycoside hydrolase family 3. While BGLC1 (At5g20950; for β-glucosidase active against xyloglucan 1) is responsible for all or most of the soluble activity, BGLC3 (At5g04885) is usually a membrane-anchored protein. Mutations in these two genes, whether on their own or combined with mutations in other exoglycosidase genes, resulted in the accumulation of partially digested xyloglucan subunits, such as GXXG, GXLG, or GXFG. While a mutation in BGLC1 had significant effects on its own, lack of BGLC3 had only minor effects. On the other hand, double bglc1 bglc3 mutants revealed a synergistic interaction that supports a role for membrane-bound BGLC3 in xyloglucan metabolism. In addition, bglc1 bglc3 was complemented by overexpression of either BGLC1 or BGLC3 In overexpression lines, BGLC3 activity was concentrated in a microsome-enriched fraction but also was present in soluble form. Finally, both genes were generally expressed in the same cell types, although, in some cases, BGLC3 was expressed at earlier stages than BGLC1 We propose that functional specialization could explain the separate localization of both enzymes, as a membrane-bound β-glucosidase could specifically digest soluble xyloglucan without affecting the wall-bound polymer.
Volume 173(2)
Pages 1017-1030
Published 2017-2
DOI 10.1104/pp.16.01713
PII pp.16.01713
PMID 27956490
PMC PMC5291047
MeSH Arabidopsis / enzymology* Arabidopsis / metabolism* Arabidopsis Proteins / metabolism* Cell Membrane / enzymology* Gene Expression Regulation, Plant Genetic Complementation Test Glucans / metabolism* Glucuronidase / metabolism Mutation / genetics Protein Binding Solubility Xylans / metabolism* alpha-L-Fucosidase / metabolism beta-Glucosidase / metabolism*
IF 5.949
Times Cited 0
Arabidopsis / Cultured plant cells, genes pst14354