Arabinogalactan-proteins from non-coniferous gymnosperms have unusual structural features
Arabinogalactan-proteins from non-coniferous gymnosperms have unusual structural features
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DOI：
10.1016/j.carbpol.2021.117831
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发表时间：
2021-02-26
影响因子：
11.2
通讯作者：
Classen, Birgit
中科院分区：
文献类型：
--
作者：
Baumann, Alexander;Pfeifer, Lukas;Classen, Birgit
阿拉伯半乳糖蛋白（AGPs）是植物细胞壁的重要信号分子，在被子植物中被广泛研究，但在裸子植物中关于AGPs的信息仍然有限。我们对裸子植物银杏、麻黄、长叶脑树和苏铁的AGPs进行了鉴定。蛋白质含量与被子植物agp相当。羟脯氨酸是连接碳水化合物部分的位点，在所有AGP中均检测到，其中苏铁AGP中含量最高（占AGP的1.1%）。有趣的是，除苏铁外，所有AGPs都含有被子植物多糖中不存在的单糖3- o -甲基鼠李糖。苏铁和麻黄的碳水化合物结构以1,3,6-连接半乳糖和末端阿拉伯糖为主，是被子植物AGP的典型特征，而银杏AGP的碳水化合物结构则以1,4-连接半乳糖为主。银杏基因组中糖基转移酶的生物信息学研究也发现，负责1,3 gal /1,6 gal AGP主干生物合成的半乳糖转移酶数量较少。
Arabinogalactan-proteins (AGPs), important signalling molecules of the plant cell wall, are structurally extensively investigated in angiosperms, but information on AGPs in gymnosperms is still limited. We characterized AGPs from the gymnosperms Ginkgo biloba, Ephedra distachya, Encephalartos longifolius and Cycas revoluta. The protein contents are comparable to that of angiosperm AGPs. Hydroxyproline is the site of linking the carbohydrate part and was detected in all AGPs with highest concentration in Cycas AGP (1.1 % of the AGP). Interestingly, with the exception of Cycas, all AGPs contained the monosaccharide 3-O-methylrhamnose not present in angiosperm polysaccharides. The carbohydrate moieties of Cycas and Ephredra showed the main components 1,3,6-linked galactose and terminal arabinose typical of angiosperm AGPs, whereas that of Ginkgo AGP was unique with 1,4-linked galactose as dominant structural element. Bioinformatic search for glycosyltransferases in Ginkgo genome also revealed a lower number of galactosyltransferases responsible for biosynthesis of the 1,3Gal/1,6-Gal AGP backbone.