A new family of RhoGEFs activates the Rop molecular switch in plants
A new family of RhoGEFs activates the Rop molecular switch in plants
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DOI：
10.1038/nature03883
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发表时间：
2005-08-25
期刊：
影响因子：
64.8
通讯作者：
Wittinghofer, A
中科院分区：
文献类型：
--
作者：
Berken, A;Thomas, C;Wittinghofer, A
在植物中，被称为Rops的小gtp结合蛋白作为信号开关，控制生长、发育和植物对各种环境刺激的反应（1-3）。Rop蛋白（植物中的Rho，拟南芥中的Rac-like和AtRac）属于ras相关gtp结合蛋白的Rho家族，通过从gtp结合的无活性构象转换为gtp结合的活性构象来打开信号通路（4,5）。激活依赖于鸟嘌呤核苷酸交换因子（gef），该因子催化缓慢的GDP解离，以进行随后的GTP结合(6)。尽管动物和酵母中存在大量rhogef(7)，但尚未在植物中发现Rop特异性gef，因此Rop激活仍然难以捉摸（1-3,8）。在这里，我们描述了一个新的RhoGEF蛋白家族，它只存在于植物中。我们在这些ropgef中定义了一个独特的结构域，称为PRONE（植物特异性Rop核苷酸交换器），该结构域仅对Rop亚家族的成员有效。它将核苷酸与Rop的分离增加了一千倍以上，并与无核苷酸的Rop形成紧密的复合物。ropgef可能代表了受体激酶到Rops信号转导过程中缺失的一环，它们的鉴定对Rho分子开关的进化具有重要意义。
In plants, the small GTP-binding proteins called Rops work as signalling switches that control growth, development and plant responses to various environmental stimuli(1-3). Rop proteins ( Rho of plants, Rac-like and AtRac in Arabidopsis thaliana) belong to the Rho family of Ras-related GTP-binding proteins that turn on signalling pathways by switching from a GDP-bound inactive to a GTP-bound active conformation(4,5). Activation depends on guanine nucleotide exchange factors ( GEFs) that catalyse the otherwise slow GDP dissociation for subsequent GTP binding(6). Although numerous RhoGEFs exist in animals and yeasts(7), no Rop-specific GEFs have yet been identified in plants and so Rop activation has remained elusive(1-3,8). Here we describe a new family of RhoGEF proteins that are exclusive to plants. We define a unique domain within these RopGEFs, termed PRONE (plant-specific Rop nucleotide exchanger), which is exclusively active towards members of the Rop subfamily. It increases nucleotide dissociation from Rop more than a thousand-fold and forms a tight complex with nucleotide-free Rop. RopGEFs may represent the missing link in signal transduction from receptor kinases to Rops and their identification has implications for the evolution of the Rho molecular switch.