Direct ligand-receptor complex interaction controls Brassica self-incompatibility
Direct ligand-receptor complex interaction controls Brassica self-incompatibility
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DOI：
10.1038/35097104
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发表时间：
2001-10-04
期刊：
影响因子：
64.8
通讯作者：
Isogai, A
中科院分区：
文献类型：
--
作者：
Takayama, S;Shimosato, H;Isogai, A
许多高等植物已经进化出自交不亲和机制来防止自花受精（1）。在芸苔属自交不亲和性中，花粉和柱头之间的识别由S基因座控制，该基因座包含三个高度多态性的基因：S受体激酶（SRK）（2）、S基因座蛋白11（SP11）（3）（也称为S基因座富含半胱氨酸的蛋白质; SCR）（4）和S基因座糖蛋白（SLG）（5）。SRK编码跨膜丝氨酸/苏氨酸激酶，其决定柱头的S-单倍型特异性（6），SP11编码富含半胱氨酸的小蛋白，其决定花粉的S-单倍型特异性（4，7，8）。SP11定位于花粉衣中（8）。据认为，在自交过程中，SP11从花粉被中分泌出来，并与柱头乳突细胞中的同源SRK相互作用，引起自交不亲和反应。SLG是一种分泌的柱头蛋白（9），与SRK胞外结构域高度同源。尽管柱头的S-单倍型特异性不需要SLG，但SLG增强了自交不亲和反应（6）;然而，这是如何实现的仍然存在争议（10-12）。在这里，我们表明，一个单一形式的S-8单倍型的SP11（S-8-SP11）与四个分子内二硫键稳定特异性结合的S-8单倍型的柱头膜诱导SRK 8的自磷酸化，SRK 8和SLG（8）一起形成一个高亲和力的受体复合物S-8-SP11柱头膜上。
Many higher plants have evolved self-incompatibility mechanisms to prevent self-fertilization(1). In Brassica self-incompatibility, recognition between pollen and the stigma is controlled by the S locus, which contains three highly polymorphic genes: S-receptor kinase (SRK)(2), S-locus protein 11 (SP11)(3) (also called S-locus cysteine-rich protein; SCR)(4) and S-locus glycoprotein (SLG)(5). SRK encodes a membrane-spanning serine/threonine kinase that determines the S-haplotype specificity of the stigma(6), and SP11 encodes a small cysteine-rich protein that determines the S-haplotype specificity of pollen(4,7,8). SP11 is localized in the pollen coat(8). It is thought that, during self-pollination, SP11 is secreted from the pollen coat and interacts with its cognate SRK in the papilla cell of the stigma to elicit the self-incompatibility response. SLG is a secreted stigma protein(9) that is highly homologous to the SRK extracellular domain. Although it is not required for S-haplotype specificity of the stigma, SLG enhances the self-incompatibility response(6); however, how this is accomplished remains controversial(10-12). Here we show that a single form of SP11 of the S-8 haplotype (S-8-SP11) stabilized with four intramolecular disulphide bonds specifically binds the stigma membrane of the S-8 haplotype to induce autophosphorylation of SRK8, and that SRK8 and SLG(8) together form a high-affinity receptor complex for S-8-SP11 on the stigma membrane.