Modulation of the Degree and Pattern of Methyl-esterification of Pectic Homogalacturonan in Plant Cell Walls IMPLICATIONS FOR PECTIN METHYL ESTERASE ACTION, MATRIX PROPERTIES, AND CELL ADHESION

摘要: Homogalacturonan (HG) is a multifunctional pectic polysaccharide of the primary cell wall matrix all land plants. HG thought to be deposited in walls highly methyl-esterified form but can subsequently de-esterified by wall-based pectin methyl esterases (PMEs) that have capacity remove ester groups from HG. Plant PMEs typically occur multigene families/isoforms, precise details functions are far clear. Most act processive or blockwise fashion resulting domains contiguous galacturonic acid residues. Such blocks cross-linked calcium gel formation and contribute intercellular adhesion. We demonstrate that, addition de-esterification, with non-blockwise distribution esters also an abundant feature plant walls. A partially epitope generated greatest abundance de-esterification spatially regulated within occurs at points separation spaces parenchymatous tissues pea other angiosperms. Analysis properties calcium-mediated gels formed pectins containing differing degrees patterns methyl-esterification indicated pattern group likely distinct mechanical porosity matrix. These findings important implications for our understanding both action on mechanisms adhesion its loss