Arabinogalactan proteins have deep roots in eukaryotes: identification of genes and epitopes in brown algae and their role in Fucus serratus embryo development
Arabinogalactan proteins have deep roots in eukaryotes: identification of genes and epitopes in brown algae and their role in Fucus serratus embryo development
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DOI：
10.1111/nph.13786
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发表时间：
2016-03-01
期刊：
影响因子：
9.4
通讯作者：
Kloareg, Bernard
中科院分区：
文献类型：
--
作者：
Herve, Cecile;Simeon, Amandine;Kloareg, Bernard
阿拉伯半乳糖蛋白(AGPs)是存在于植物细胞表面的高度糖基化、富含羟基脯氨酸的蛋白质，在植物的发育过程中起着关键作用。褐藻是一种海洋、多细胞、光合作用的真核生物。它们属于Stramenopiles门，与陆地植物和绿藻(绿藻)无关。褐藻与其他多细胞生物有共同的进化特征，包括富含碳水化合物的细胞壁。它们在细胞壁组成上与植物明显不同，AGP在褐藻中还没有报道。在这里，我们研究了这一品系中是否存在嵌合的AGP类核心蛋白。我们报告了褐藻模型Etocarpus silillosus的基因组序列编码AGP蛋白骨架基序，其基因背景与陆地植物中已知的有很大不同。我们发现在一系列褐藻细胞壁萃取物中存在AGP糖链表位。我们证明了这些嵌合的AGP类核心蛋白在Fucales目的胚胎中受到发育调控，并表明AGP功能的丧失严重损害了早期胚胎发育的进程。我们的发现揭示了AGPs在细胞壁感知中的作用，并提出了真核细胞AGPs的起源和进化的问题。
Arabinogalactan proteins (AGPs) are highly glycosylated, hydroxyproline-rich proteins found at the cell surface of plants, where they play key roles in developmental processes. Brown algae are marine, multicellular, photosynthetic eukaryotes. They belong to the phylum Stramenopiles, which is unrelated to land plants and green algae (Chloroplastida). Brown algae share common evolutionary features with other multicellular organisms, including a carbohydrate-rich cell wall. They differ markedly from plants in their cell wall composition, and AGPs have not been reported in brown algae.Here we investigated the presence of chimeric AGP-like core proteins in this lineage.We report that the genome sequence of the brown algal model Ectocarpus siliculosus encodes AGP protein backbone motifs, in a gene context that differs considerably from what is known in land plants. We showed the occurrence of AGP glycan epitopes in a range of brown algal cell wall extracts. We demonstrated that these chimeric AGP-like core proteins are developmentally regulated in embryos of the order Fucales and showed that AGP loss of function seriously impairs the course of early embryogenesis.Our findings shine a new light on the role of AGPs in cell wall sensing and raise questions about the origin and evolution of AGPs in eukaryotes.