果胶分子量变化对<i>拟南芥</i>原代细胞壁结构，动力学和多糖相互作用的影响：固态NMR的见解,Biomacromolecules

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果胶分子量变化对拟南芥原代细胞壁结构，动力学和多糖相互作用的影响：固态NMR的见解
Biomacromolecules ( IF 5.5 ) Pub Date : 2017-08-22 00:00:00 , DOI: 10.1021/acs.biomac.7b00888
Pyae Phyo ₁ , Tuo Wang ₁ , Chaowen Xiao ₂ , Charles T. Anderson ₂ , Mei Hong ₁

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最近基于完整细胞壁的2D ¹³ C固态NMR光谱报道了植物细胞壁中重要的纤维素-果胶相互作用，但尚未探讨这些相互作用如何影响细胞生长。在这里，我们描述2条拟南芥与表达的改变线涉及聚半乳糖醛EXPANSION1（PGX1）基因，其编码一个多聚半乳糖裂解homogalacturonan（HG）。PGX1 ^AT植物过表达PGX1，具有较低分子量的HG，并且生长较大，而PGx1-2敲除植物具有较高分子量的HG，并且生长较小。定量¹³C固态NMR光谱显示，PGX1 ^AT细胞壁的半乳糖醛酸和木糖含量较低，且HG甲基酯化程度高于对照，而高分子量pgx1-2壁的半乳糖醛酸含量和甲基酯化程度与对照相似。¹ H转移的¹³ C INEPT光谱表明，原纤维间HG骨架更聚集，而RG-1侧链比pgx1-2壁更分散在PGX1 ^AT细胞壁中。相反，与pgx1-2相比，PGX1 ^AT壁中与纤维素接近的果胶与纤维素的流动性更高，并且具有较弱的交叉峰。墙壁。总之，这些结果表明，聚半乳糖醛酸酶介导的植物生长伴随着酯化作用的增加和HG交联的减少，原纤维间HG的聚集增加以及HG与纤维素之间的相互作用减弱。这些结构和动力学上的差异为果胶如何影响细胞生长过程中的壁动力学提供了分子见解。

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Effects of Pectin Molecular Weight Changes on the Structure, Dynamics, and Polysaccharide Interactions of Primary Cell Walls of Arabidopsis thaliana: Insights from Solid-State NMR

Significant cellulose–pectin interactions in plant cell walls have been reported recently based on 2D ¹³C solid-state NMR spectra of intact cell walls, but how these interactions affect cell growth has not been probed. Here, we characterize two Arabidopsis thaliana lines with altered expression of the POLYGALACTURONASE INVOLVED IN EXPANSION1 (PGX1) gene, which encodes a polygalacturonase that cleaves homogalacturonan (HG). PGX1^AT plants overexpress PGX1, have HG with lower molecular weight, and grow larger, whereas pgx1-2 knockout plants have HG with higher molecular weight and grow smaller. Quantitative ¹³C solid-state NMR spectra show that PGX1^AT cell walls have lower galacturonic acid and xylose contents and higher HG methyl esterification than controls, whereas high molecular weight pgx1-2 walls have similar galacturonic acid content and methyl esterification as controls. ¹H-transferred ¹³C INEPT spectra indicate that the interfibrillar HG backbones are more aggregated whereas the RG-I side chains are more dispersed in PGX1^AT cell walls than in pgx1-2 walls. In contrast, the pectins that are close to cellulose become more mobile and have weaker cross peaks with cellulose in PGX1^AT walls than in pgx1-2 walls. Together, these results show that polygalacturonase-mediated plant growth is accompanied by increased esterification and decreased cross-linking of HG, increased aggregation of interfibrillar HG, and weaker HG–cellulose interactions. These structural and dynamical differences give molecular insights into how pectins influence wall dynamics during cell growth.

更新日期：2017-08-22

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