Ralet Marie-Christine, Crépeau Marie-Jeanne, Lefèbvre Jacques, Mouille Grégory, Höfte Herman, Thibault Jean-François
INRA, UR1268 Biopolymères Interactions Assemblages, F-44300 Nantes.
Biomacromolecules. 2008 May;9(5):1454-60. doi: 10.1021/bm701321g. Epub 2008 Mar 21.
Pectins are a family of highly complex multifunctional cell wall polysaccharides. Little is known on the relation between pectin structure, hydrodynamic properties, and cellular function. In this study, we took advantage of the Arabidopsis pectin mutant quasimodo2 (qua2), which specifically lacks half of its homogalacturonan blocks, to study the relationship between the amount of homogalacturonan blocks and the hydrodynamic properties of pectins. It was first shown that, in qua2 pectins, homogalacturonans had maintained the same size as those in the wild type. The persistence lengths of isolated homogalacturonan and rhamnogalacturonan-I blocks were then measured and it was shown that homogalacturonan was over 4-fold more rigid than rhamnogalacturonan-I. WT and qua2 pectins were next compared and it appeared that the specific reduction of the number of homogalacturonan blocks leads to an increased flexibility of qua2 pectins. These results show for the first time how mutant pectins can be used to demonstrate the opposite influence of rhamnogalacturonan-I and homogalacturonan blocks on the hydrodynamic properties of pectins.
果胶是一类高度复杂的多功能细胞壁多糖。关于果胶结构、流体动力学性质和细胞功能之间的关系，人们了解甚少。在本研究中，我们利用拟南芥果胶突变体quasimodo2（qua2），该突变体特异性地缺失了其一半的同型半乳糖醛酸聚糖块，来研究同型半乳糖醛酸聚糖块的数量与果胶流体动力学性质之间的关系。首先表明，在qua2果胶中，同型半乳糖醛酸聚糖的大小与野生型中的相同。然后测量了分离的同型半乳糖醛酸聚糖和鼠李半乳糖醛酸聚糖-I块的持久长度，结果表明同型半乳糖醛酸聚糖的刚性比鼠李半乳糖醛酸聚糖-I高4倍以上。接下来比较了野生型（WT）和qua2果胶，结果显示同型半乳糖醛酸聚糖块数量的特异性减少导致qua2果胶的柔韧性增加。这些结果首次表明突变果胶可用于证明鼠李半乳糖醛酸聚糖-I和同型半乳糖醛酸聚糖块对果胶流体动力学性质的相反影响。
