ROPs:植物细胞内多种信号通路的分子开关

植物RHO相关蛋白GTPases(RHO-related GTPases of plants, ROPs)是广泛存在于植物中的一类信号转导G蛋白(又称GTP结合蛋白),其通过结合GDP或GTP在非活性和活性状态间进行切换,进而在细胞极性控制、形态发育、激素水平调控、逆境反应等诸多植物生命活动的信号转导过程中扮演重要的分子开关角色。本文对ROP蛋白的结构域及基于蛋白质结构分类进行了介绍,并对拟南芥、玉米、水稻和大麦中的ROP家族蛋白质进行了系统进化分析。分析结果表明,这些植物中的ROP蛋白根据蛋白质结构域组成可分为Ⅰ类(typeⅠ)和Ⅱ类(typeⅡ)两种类型,而根据蛋白质序列的保守性可将其在植物中的ROP蛋白划分为4个进化枝。本综述不但对ROP蛋白作为分子开关在细胞内调控各种信号通路的机制进行了叙述,还对ROP在花粉管、根毛及植物表皮铺盖细胞极性发育,以及其他抗逆反应中的具体作用和机制及研究进展进行了阐述。本文还对ROP蛋白在ABA、IAA、BR等植物激素信号传导过程中的调控作用及研究进展进行了阐述。本文对植物ROP蛋白研究过程中尚未解决的问题,例如不同的ROP蛋白在同一个信号通路中的作用为何如此不同,以及ROP是如何协调不同的信号通路以共同调控一个植物发育或者生理过程等问题进行了总结,并在此基础上对未来的研究方向进行了展望。

ROPs: Molecular Switches of Multiple Signal Pathways in Plant Cells

RHO-related GTPases of plants (ROPs) are a class of signal transduction G proteins (also known as GTP binding proteins) widely existing in plants. ROP proteins act as "molecular switches" to regulate the signal transduction process during cellular activities such as plant cell polarity regulation, plant morphological development, hormone level regulation, stress responses and many other life activities by shifting between inactive GDP-binding and active GTP-binding forms in the cells. In this review, the domain structure, classification, the mechanism of activity regulation and biological functions of ROP proteins were summarize. Furthermore, ROP proteins from Arabidopsis, maize, rice and barley were phylogenetically analyzed. The results show that ROP proteins were classified into two types based on the domain structure of the proteins. However, these ROP proteins were divided into 4 clades based on the similarity of protein sequences. Furthermore, the mechanism of ROP proteins as a molecular switch regulating various signaling pathways in cells, and the specific functions and mechanisms of ROPs in the polarized growth of pollen tubes, root hairs and plant pavement cells and other stress responses were characterized. In addition, the research progress of the function of ROPs in plant hormones such as ABA, IAA and BR mediated signal transduction were described as well. At last, the unanswered questions such as why different ROP proteins play distinct roles in the same signaling pathway and how ROPs coordinate different signal pathways to jointly regulate a plant’s development or physiological process were discussed, which may shed light on future research.