A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets
A genome-wide analysis of Arabidopsis Rop-interactive CRIB motif-containing proteins that act as Rop GTPase targets
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DOI：
10.1105/tpc.13.12.2841
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发表时间：
2001-12-01
期刊：
影响因子：
11.6
通讯作者：
Yang, ZB
中科院分区：
文献类型：
--
作者：
Wu, G;Gu, Y;Yang, ZB
植物特异性 Rop 家族 GTP 酶是植物生长、发育和对环境响应过程中许多过程的多功能分子开关。为了了解 Rop 如何实现其信号传导功能的多功能性，我们结合酵母双杂交方法、生物信息学工具和花粉中强大的功能测定，对假定的 Rop 靶点进行了全基因组鉴定。在这项研究中，我们鉴定了 11 个拟南芥基因，它们编码新的蛋白质，称为 RIC（含 Rop 相互作用的 CRIB 基序的蛋白质），其中包含与 GTP 结合的 Rop1 发生特异性相互作用所需的 CRIB（Cdc42/Rac 相互作用结合）基序。 RIC 各不相同，分为五组，在保守的 Rop 交互域之外，它们几乎没有序列同源性。拟南芥花粉中表达的九种 Ric 基因在烟草花粉管中过度表达，导致不同的表型，这意味着各种 RIC 具有不同的功能。 RIC3（III 组）和 RIC4（V 组）都像 Rop1 一样引起去极化生长，并显示 Rop1 增强的花粉管尖端定位，表明这些 RIC 可能是 Rop1 的两个不同靶标。相反，RIC10（I组）促进花粉管伸长，但不影响花粉管生长极性，并且显示出与Rop1无关的细胞质定位，表明RIC10可能参与可能由不同Rop控制的与Rop1无关的途径。所有其他 RIC 的表达都会导致花粉管中不同程度的生长抑制。此外，这些抑制性 RIC 在花粉管中也表现出不同的定位模式。我们的结果表明，各种 RIC 已进化为与 Rops 有差异地相互作用，并在花粉管中执行不同的功能，逆转录酶介导的聚合酶链反应分析表明，九种 RIC 中的六种在拟南芥植物的不同部分中表达。基于这些观察，我们提出 RIC 作为 Rop GTPase 靶标发挥作用，控制植物中各种 Rop 依赖性信号通路。
The plant-specific Rop family GTPases are versatile molecular switches in many processes during plant growth, development, and responses to the environment. To understand how Rop achieves its functional versatility in signaling, we performed a genome-wide identification of putative Rop targets using a combination of the yeast two-hybrid method, bioinformatic tools, and a robust functional assay in pollen. In this study, we have identified 11 Arabidopsis genes encoding novel proteins, termed RICs (for Rop-interactive CRIB motif-containing proteins), that contain a CRIB (for Cdc42/Rac-interactive binding) motif required for their specific interaction with GTP-bound Rop1. RICs are divergent and classified into five groups that share little sequence homology outside of the conserved Rop-interactive domain. Overexpression in tobacco pollen tubes of the nine Ric genes that are expressed in Arabidopsis pollen causes distinct phenotypes, implying distinct functions for various RICs. RIC3 (group III) and RIC4 (group V) both cause depolarized growth like Rop1 and display Rop1-enhanced localization to the tip of pollen tubes, suggesting that these RICs may be two distinct targets of Rop1. In contrast, RIC10 (group I) promotes pollen tube elongation but does not affect pollen tube growth polarity and shows Rop1-independent localization to the cytoplasm, suggesting that RIC10 may participate in a Rop1-independent pathway probably controlled by a different Rop. Expression of all other RICs causes various degrees of growth inhibition in pollen tubes. Furthermore, these inhibitory RICs also exhibit distinct patterns of localization in pollen tubes. Our results suggest that various RICs have evolved to interact with Rops differentially and to perform distinct functions in pollen tubes, Reverse transcriptase-mediated polymerase chain reaction analysis showed that six of the nine RICs are expressed in various parts of Arabidopsis plants. On the basis of these observations, we propose that RICs function as Rop GTPase targets that control various Rop-dependent signaling pathways in plants.