CGR3: A Golgi-Localized Protein Influencing Homogalacturonan Methylesterification
CGR3: A Golgi-Localized Protein Influencing Homogalacturonan Methylesterification
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DOI：
10.1093/mp/ssr012
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发表时间：
2011-09-01
期刊：
影响因子：
27.5
通讯作者：
Brandizzi, Federica
中科院分区：
文献类型：
--
作者：
Held, Michael A.;Be, Evan;Brandizzi, Federica
植物细胞壁是为植物细胞提供结构和机械支持的复杂结构，并最终负责植物的结构和形式。果胶是植物细胞壁的一大群复杂多糖，其在高尔基体中产生并分泌到细胞壁。果胶的甲酯化反应是影响细胞壁动力学性质的重要因素。在这里，我们报告一个未知功能的蛋白质发现使用广泛的蛋白质组学分析棉花高尔基体。通过生物信息学分析，我们确定了这种蛋白质的直系同源物，在这里命名为棉花高尔基体相关3（CGR 3）在拟南芥中，并发现它与S-腺苷甲硫氨酸甲基转移酶共享保守残基。我们建立了CGR 3定位于高尔基体，CGR 3基因的表达与几个细胞壁生物合成基因的表达相关，这表明该蛋白质在果胶修饰中可能起作用。与此假设一致，免疫荧光显微镜与抗体的同型半乳糖醛酸果胶（HG）表明，细胞壁的CGR 3敲除突变体和植物过表达CGR 3的减少和增加，分别在HG甲酯化。我们的研究结果表明，CGR 3在拟南芥的homogalacturonan的甲基化中发挥作用。
Plant cell walls are complex structures that offer structural and mechanical support to plant cells and are ultimately responsible for plant architecture and form. Pectins are a large group of complex polysaccharides of the plant cell wall that are made in the Golgi and secreted to the wall. The methylesterification of pectins is believed to be an important factor for the dynamic properties of the cell wall. Here, we report on a protein of unknown function discovered using an extensive proteomics analysis of cotton Golgi. Through bioinformatic analyses, we identified the ortholog of such protein, here named cotton Golgi-related 3 (CGR3) in Arabidopsis and found that it shares conserved residues with S-adenosylmethionine methyltransferases. We established that CGR3 is localized at the Golgi apparatus and that the expression of the CGR3 gene is correlated with that of several cell wall biosynthetic genes, suggesting a possible role of the protein in pectin modifications. Consistent with this hypothesis, immunofluorescence microscopy with antibodies for homogalacturonan pectins (HG) indicated that the cell walls of cgr3 knockout mutants and plants overexpressing CGR3 are decreased and increased in HG methylesterification, respectively. Our results suggest that CGR3 plays a role in the methylesterification of homogalacturonan in Arabidopsis.