TheMicrotubule-Associated ProteinMAP18 Affects ROP2 GTPase Activity during Root Hair Growth1[OPEN]
TheMicrotubule-Associated ProteinMAP18 Affects ROP2 GTPase Activity during Root Hair Growth1[OPEN]
复制标题
微管相关蛋白MAP18 在根毛生长过程中影响 ROP2 GTP 酶活性1[打开]
DOI：
10.1104/pp.16.01243
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发表时间：
2017-05-01
期刊：
影响因子：
7.4
通讯作者：
Fu, Ying
中科院分区：
文献类型：
--
作者：
Kang, Erfang;Zheng, Mingzhi;Fu, Ying
极性部位的建立和维持对根尖的生长至关重要。我们先前报道了拟南芥微管相关蛋白18（MAP 18）在控制花粉管生长和根毛伸长方向中的功能。此外，据报道Rop GTPase ROP 2是拟南芥根毛起始和顶端生长的正调节因子。ROP 2的功能丧失和MAP 18的敲低都导致根毛长度的减少，而MAP 18或ROP 2的过表达导致多个尖端或分支毛发表型。然而，目前还不清楚MAP 18和ROP 2是否协调调节根毛生长。在这项研究中，我们证明了MAP 18和ROP 2在遗传和功能上相互作用。MAP 18在体外和体内与ROP 2物理相互作用，并优先结合ROP 2蛋白的无活性形式。MAP 18在根尖生长期间促进ROP 2活性。进一步的研究表明，MAP 18与RhoGTIPOGDP解离抑制剂1/SUPERCENTIPE 1竞争结合ROP 2，进而影响活性ROP 2在根尖质膜中的定位。这些结果揭示了MAP 18在根毛生长过程中调节ROP 2活化的新功能。
Establishment and maintenance of the polar site are important for root hair tip growth. We previously reported that Arabidopsis (Arabidopsis thaliana) MICROTUBULE-ASSOCIATED PROTEIN18 (MAP18) functions in controlling the direction of pollen tube growth and root hair elongation. Additionally, the Rop GTPase ROP2 was reported as a positive regulator of both root hair initiation and tip growth in Arabidopsis. Both loss of function of ROP2 and knockdown of MAP18 lead to a decrease in root hair length, whereas overexpression of either MAP18 or ROP2 causes multiple tips or a branching hair phenotype. However, it is unclear whether MAP18 and ROP2 coordinately regulate root hair growth. In this study, we demonstrate that MAP18 and ROP2 interact genetically and functionally. MAP18 interacts physically with ROP2 in vitro and in vivo and preferentially binds to the inactive form of the ROP2 protein. MAP18 promotes ROP2 activity during root hair tip growth. Further investigation revealed that MAP18 competes with RhoGTPase GDP DISSOCIATION INHIBITOR1/SUPERCENTIPEDE1 for binding to ROP2, in turn affecting the localization of active ROP2 in the plasma membrane of the root hair tip. These results reveal a novel function of MAP18 in the regulation of ROP2 activation during root hair growth.