Molecular and biochemical characterization of rice pectin methylesterase inhibitors (OsPMEIs)
Molecular and biochemical characterization of rice pectin methylesterase inhibitors (OsPMEIs)
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DOI：
10.1016/j.plaphy.2016.01.021
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发表时间：
2016-04-01
影响因子：
6.5
通讯作者：
Lee, Chanhui
中科院分区：
文献类型：
--
作者：
Hong Phuong Nguyen;Jeong, Ho Young;Lee, Chanhui
细胞壁的修饰，如细胞壁水解酶的部分降解和解聚是正常的细胞过程，是不同细胞类型的功能所必需的。果胶是主要的细胞壁多糖之一，主要存在于初生细胞壁和中层中，并且主要通过细胞壁定位的果胶甲基酯酶（PMEs）进行壁内修饰。分子生物学研究表明，PMEs的酶活性受多种果胶甲酯酶抑制剂（PMEIs）的控制，从而控制果胶甲酯化状态。虽然在拟南芥中的一些研究已经显示了这种PMEI介导的调节在细胞壁的生物物理特性中的重要性，但对水稻PMEI的分子生理功能知之甚少。我们在水稻基因组中发现了49个PMEI家族成员。通过实时定量PCR和Meta表达分析对它们的转录水平进行分析，结果表明它们在空间和时间上受到调节，并且响应于不同的胁迫。细胞壁结合的甲酯的定量表明，果胶甲酯化的程度是发育调节，特别是，更高的PMEI活动中检测到从嫩叶制备的细胞壁蛋白。此外，活性测定表明，两个重组OsPMEI蛋白（OsPMEI8和12）能够抑制商业PME蛋白的酶活性。亚细胞定位结果表明，OsPMEI8定位于中板层，OsPMEI12定位于质膜和细胞核。总之，我们的研究结果提供了第一个分子和生物化学证据的功能特性的PMEIs在水稻生长和发育。(C)2016 Elsevier Masson SAS。All rights reserved.
Cell wall modifications such as partial degradation and depolymerization by cell wall hydrolases are normal cellular processes and are required for the functionalities of different cell types. Pectin, one of the major cell wall polysaccharides, is predominantly found in primary cell walls and middle lamellae and is subjected to in muro modification, primarily by cell wall-localized pectin methylesterases (PMEs). Molecular biochemical studies have demonstrated that enzymatic activities of PMEs are governed by multiple pectin methylesterase inhibitors (PMEIs), which consequently control the pectin methylesterification status. Although a few studies in Arabidopsis have shown the importance of this PMEI-mediated regulation in the biophysical properties of cell walls, little is known about the molecular physiological functions of rice PMEIs. We found 49 members of the PMEI family in the rice genome. Analysis of their transcript levels by quantitative real-time PCR and meta expression analysis showed that they are regulated spatially and temporally, as well as in response to diverse stresses. Quantification of cell wall bound methylesters indicated that the degree of pectin methylesterification is developmentally regulated; in particular, higher PMEI activities were detected in cell wall proteins prepared from young leaves. Furthermore, an activity assay demonstrated that two recombinant OsPMEI proteins (OsPMEI8 and 12) were able to inhibit the enzymatic activity of a commercial PME protein. Subcellular localization indicated that OsPMEI8 is targeted to the middle lamella and OsPMEI12 is localized in the plasma membrane and nucleus. Taken together, our findings provide the first molecular and biochemical evidence for functional characterization of PMEIs in rice growth and development. (C) 2016 Elsevier Masson SAS. All rights reserved.