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A positive feedback circuit for ROP-mediated polar growth
Molecular Plant ( IF 27.5 ) Pub Date : 2020-11-30 , DOI: 10.1016/j.molp.2020.11.017
En Li 1 , Yu-Ling Zhang 1 , Xuelian Shi 1 , Han Li 1 , Xuefeng Yuan 2 , Sha Li 1 , Yan Zhang 1
Affiliation  

Tip growth is a special type of polarized growth in which a single and unique polarization site is established and maintained. Rho of Plants (ROP) proteins, which represent the only class of Rho GTPases in plants, regulate tip growth. The dynamic and asymmetric distribution of ROPs is critical for the establishment and maintenance of tip growth, and requires at least one positive feedback loop, which is still elusive. Here, we report a positive feedback circuit essential for tip growth of root hairs, in which ROPs, ROP activators and effectors, and AGC1.5 subfamily kinases are interconnected by sequential oligomerization and phosphorylation. AGC1.5 subfamily kinases interact with and phosphorylate two guanine nucleotide exchange factors (GEFs) of ROPs, RopGEF4 and RopGEF10. They also interact with two ROP effectors, ICR2/RIP3 and MIDD1/RIP4, which bridge active ROPs with AGC1.5. Functional loss of the AGC1.5 subfamily kinases or ICR2 and MIDD1 compromised root hair growth due to reduced ROP signaling. We found that asymmetric targeting of RopGEF4 and RopGEF10 is controlled by AGC1.5-dependent phosphorylation. Interestingly, we discovered that the ROP effectors recruit AGC1.5 to active ROP domains at the plasma membrane during root hair growth and are critical for AGC1.5-dependent phosphorylation of RopGEFs. Given the large number of AGC kinases in plants, this positive feedback circuit may be a universal theme for plant cell polar growth.



中文翻译:

ROP介导的极性生长的正反馈电路

尖端生长是一种特殊类型的极化生长,其中建立并维持单一且独特的极化位点。Rho of Plants (ROP) 蛋白代表植物中唯一的一类 Rho GTP 酶,可调节尖端生长。ROP 的动态和不对称分布对于尖端生长的建立和维持至关重要,并且至少需要一个正反馈回路,这仍然难以捉摸。在这里,我们报告了一个对根毛尖端生长必不可少的正反馈电路,其中 ROP、ROP 激活子和效应子以及 AGC1.5 亚家族激酶通过顺序寡聚化和磷酸化相互连接。AGC1.5 亚家族激酶与 ROP、RopGEF4 和 RopGEF10 的两种鸟嘌呤核苷酸交换因子 (GEF) 相互作用并使其磷酸化。它们还与两个 ROP 效应器 ICR2/RIP3 和 MIDD1/RIP4 相互作用,它将主动 ROP 与 AGC1.5 桥接起来。AGC1.5 亚家族激酶或 ICR2 和 MIDD1 的功能丧失会由于 ROP 信号减少而影响根毛生长。我们发现 RopGEF4 和 RopGEF10 的不对称靶向受 AGC1.5 依赖性磷酸化控制。有趣的是,我们发现 ROP 效应器在根毛生长过程中将 AGC1.5 募集到质膜上的活性 ROP 结构域,并且对于 RopGEF 的 AGC1.5 依赖性磷酸化至关重要。鉴于植物中存在大量 AGC 激酶,这种正反馈回路可能是植物细胞极性生长的普遍主题。5 依赖性磷酸化。有趣的是,我们发现 ROP 效应器在根毛生长过程中将 AGC1.5 募集到质膜上的活性 ROP 结构域,并且对于 RopGEF 的 AGC1.5 依赖性磷酸化至关重要。鉴于植物中存在大量 AGC 激酶,这种正反馈回路可能是植物细胞极性生长的普遍主题。5 依赖性磷酸化。有趣的是,我们发现 ROP 效应器在根毛生长过程中将 AGC1.5 募集到质膜上的活性 ROP 结构域,并且对于 RopGEF 的 AGC1.5 依赖性磷酸化至关重要。鉴于植物中存在大量 AGC 激酶,这种正反馈回路可能是植物细胞极性生长的普遍主题。

更新日期:2020-11-30
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