Structural Diversity and Function of Xyloglucan Sidechain Substituents

Abstract

Xyloglucan (XyG) is a hemicellulose found in the cell walls of all land plants including early-divergent groups such as liverworts, hornworts and mosses. The basic structure of XyG, a xylosylated glucan, is similar in all of these plants but additional substituents can vary depending on plant family, tissue, and developmental stage. A comprehensive list of known XyG sidechain substituents is assembled including their occurrence within plant families, thereby providing insight into the evolutionary origin of the various sidechains. Recent advances in DNA sequencing have enabled comparative genomics approaches for the identification of XyG biosynthetic enzymes in Arabidopsis thaliana as well as in non-model plant species. Characterization of these biosynthetic genes not only allows the determination of their substrate specificity but also provides insights into the function of the various substituents in plant growth and development.

Monitoring Polysaccharide Dynamics in the Plant Cell Wall

“…The side chain substitution pattern of XyG can vary depending on the plant species (Schultink et al, 2014). However, recent analyses revealed that XyG structures can be tissue specific (Lampugnani et al, 2013;Dardelle et al, 2015;Liu et al, 2015).…”

Functional and structural characterization of a potent GH74 endo‐xyloglucanase from the soil saprophyte Cellvibrio japonicus unravels the first step of xyloglucan degradation

“…galactopyranosyl, fucopyranosyl and arabinofuranosyl residues) according to plant tissue and species (Fig. 1) [10]. As a result of this structural complexity, complete XyG saccharification requires a consortium of endo-acting and exoacting glycoside hydrolases [11,12].…”

The Presence of Fucogalactoxyloglucan and Its Synthesis in Rice Indicates Conserved Functional Importance in Plants

“…The side-chain substitutions on XyG can be structurally diverse depending on plant species, tissue type, and developmental stage of the tissue (Pauly et al, 2001;Hoffman et al, 2005;Peña et al, 2008;Harris, 2009, 2012;Lampugnani et al, 2013;Schultink et al, 2014). A one-letter code nomenclature has been established to specify the XyG side-chain substitutions (Fry et al, 1993;Tuomivaara et al, 20145).…”