《植物生理学报》 2018, 54(8): 1263-1271

植物阿拉伯半乳聚糖蛋白AG糖链的合成

秦丽霞¹, 李学宝², 许文亮^2,*

¹山西省农业科学院棉花研究所, 山西运城044000; ²华中师范大学生命科学学院, 遗传调控与整合生物学湖北省重点实验室, 武汉430079

通信作者：许文亮；E-mail: wenliangxu@mail.ccnu.edu.cn

摘　要：

阿拉伯半乳聚糖蛋白(arabinogalactan-proteins, AGPs)是一类高度糖基化的富含羟脯氨酸(hydroxyproline, Hyp)的糖蛋白, 广泛分布于植物的细胞壁、质膜和胞外分泌物中, 在植物生长和发育的多个过程中发挥重要作用。主要进行两种翻译后修饰, 首先通过脯氨酸羟化酶催化的脯氨酸羟基化, 随后在一些羟脯氨酸的羟基上添加阿拉伯半乳聚糖(arabinogalactan, AG), 以AG为主的多糖可占到AGP分子量的90%, 这意味着多糖链主要决定着AGP与其他分子间的相互作用进而影响其功能。从2010年2个能特异糖基化AGP的糖基转移酶AtFUT4和AtFUT6被鉴定以来, 越来越多参与AGP多糖合成的糖基转移酶被鉴定。本文综述了近10年来参与AGP多糖链合成的糖基转移酶的研究进展, 并结合棉纤维中AGP研究, 讨论了多糖合成的机制及亟待解决的问题, 展望了其发展趋势。

关键词：阿拉伯半乳聚糖; AG糖链; 糖基化; 糖基转移酶

收稿：2018-03-01   修定：2018-05-04

资助：国家自然科学基金(31671735, 31371234, 31601350)、湖北省自然科学基金(2016CFA071)、中央高校基本科研业务费(CCNU18TS021)。

Biosynthesis of arabinogalactan (AG) polysaccharides of arabinogalactan-proteins in plants

QIN Li-Xia¹, LI Xue-Bao², XU Wen-Liang^2,*

¹Institute of Cotton, Shanxi Academy of Agricultural Science, Yuncheng, Shanxi 044000, China; ²Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China

Corresponding author: XU Wen-Liang; E-mail: wenliangxu@mail.ccnu.edu.cn

Abstract:

Arabinogalactan-proteins (AGPs) are highly glycosylated hydroxyproline (Hyp)-rich glycoproteins. They are widely distributed in cell walls, plasma membranes and extracellular secretions of plants and play important roles in various processes of plant growth and development. These proteins undergo extensive posttranslational modification, which includes the conversion of proline (Pro) residues to hydroxyproline (Hyp) and subsequent addition of arabinogalactan (AG) polysaccharides to Hyp residues. Given that the carbohydrate moieties typically account for up to 90% of the molecular mass of AGPs, they are probable to define the interactive surface of the molecules and hence their functions. Since AtFUT4 and AtFUT6, two AGP-specific enzymes, were first characterized in Arabidopsis in 2010, more and more glycosyltransferases for AGP glycosylation were characterized. This paper reviews the recent progress on glycosyltransferases involved in AG biosynthesis during the last ten years. In combination with AGP research performed during cotton fiber development, possible mechanism of AG sugar biosynthesis and future research challenges are also discussed.

Key words: arabinogalactan-proteins; AG polysaccharide; glycosylation; glycosyltransferases