Modulation of the Degree and Pattern of Methyl-esterification of Pectic Homogalacturonan in Plant Cell Walls
By W. Willats, C. Orfila, G. Limberg, H. Buchholt, G. van Alebeek, A. Voragen, S. Marcus, Tove M.I.E. Christensen, Jørn Dalgaard Mikkelsen, Brent S. Murray and 1 more. Journal of Biological Chemistry, 2001
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Homogalacturonan (HG) is a multifunctional pectic polysaccharide of the primary cell wall matrix of all land plants. HG is thought to be deposited in cell walls in a highly methyl-esterified form but can be subsequently de-esterified by wall-based pectin methyl esterases (PMEs) that have the capacity to remove methyl ester groups from HG. Plant PMEs typically occur in multigene families/isoforms, but the precise details of the functions of PMEs are far from clear. Most are thought to act in a processive or blockwise fashion resulting in domains of contiguous de-esterified galacturonic acid residues. Such de-esterified blocks of HG can be cross-linked by calcium resulting in gel formation and can contribute to intercellular adhesion. We demonstrate that, in addition to blockwise de-esterification, HG with a non-blockwise distribution of methyl esters is also an abundant feature of HG in primary plant cell walls. A partially methyl-esterified epitope of HG that is generated in greatest abundance by non-blockwise de-esterification is spatially regulated within the cell wall matrix and occurs at points of cell separation at intercellular spaces in parenchymatous tissues of pea and other angiosperms. Analysis of the properties of calcium-mediated gels formed from pectins containing HG domains with differing degrees and patterns of methyl-esterification indicated that HG with a non-blockwise pattern of methyl ester group distribution is likely to contribute distinct mechanical and porosity properties to the cell wall matrix. These findings have important implications for our understanding of both the action of pectin methyl esterases on matrix properties and mechanisms of intercellular adhesion and its loss in plants.
Subfields: Food Science, Molecular Biology, Plant Science
View Paper: https://www.semanticscholar.org/paper/410cd7b5aee2259690188fad50e9c292ffd28640
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Citations in the corpus
- Intercellular adhesion and cell separation in plants (2003, unknown): “Since the galacturonan that binds the LM7 monoclonal antibody is restricted to the reinforcing zones and to the region lining the intercellular space (Willats et al. 2001), it is possible that this polymer is continuously deposited just ahead of the point where the cell walls diverge; the reinforcin”
- Pectin: cell biology and prospects for functional analysis (2001, background): “A. LM7 binds specifically to HGA with a non-block-wise distribution of methyl esters and its binding is restricted to regions of cell walls lining intercellular spaces, being particularly abundant at the junction between adhered and separated primary cell walls (Willats et al., 2001).”
- If Homogalacturonan Were a Side Chain of Rhamnogalacturonan I. Implications for Cell Wall Architecture1 (2003, background): “…be present throughout the wall, except in the middle lamella region; (d) AG-II epitopes tend to be localized close to the plasma membrane or in walls of particular cell types, for example, tracheary elements (Ridley et al., 2001, refs. therein; Willats et al., 2001a, 2001b; Voragen et al., 2003).”