Dynamic PIN-FORMED auxin efflux carrier phosphorylation at the plasma membrane controls auxin efflux-dependent growth
Dynamic PIN-FORMED auxin efflux carrier phosphorylation at the plasma membrane controls auxin efflux-dependent growth
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DOI：
10.1073/pnas.1614380114
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发表时间：
2017-01-31
影响因子：
11.1
通讯作者：
Schwechheimer, Claus
中科院分区：
文献类型：
--
作者：
Weller, Benjamin;Zourelidou, Melina;Schwechheimer, Claus
植物激素生长素的定向分布对于植物发育至关重要。定向生长素转运由极性分布的 PIN 型 (PIN) 生长素外排载体介导。我们之前已经证明，有效的 PIN1 介导的生长素流出需要通过拟南芥中四个丝氨酸 S1-S4 的磷酸化来激活。布雷菲德菌素 A (BFA) 敏感的 D6 蛋白激酶 (D6PK) 和 BFA 不敏感的 PINOID (PID) 通过所有四个磷酸位点的磷酸化来磷酸化并激活 PIN1。 PID（但不是 D6PK）也可以诱导 PIN1 极性转变，似乎是通过 S1-S3 的磷酸化实现的。迄今为止，D6PK 和 PID 对 PIN1 极性的不同影响归因于它们对四个 PIN1 磷酸位点的不同磷酸位点偏好。我们使用磷酸位点特异性抗体原位绘制了 S1-S4 处的 PIN1 磷酸化图谱。我们检测到不同根细胞类型、胚胎和芽顶端分生组织的基部（根向）和顶端（芽向）质膜 PIN1 磷酸位点的磷酸化。因此，所有磷酸位点的 PIN1 磷酸化通常遵循主要的 PIN1 分布，但不限于细胞的特定极性侧。基底质膜和顶端质膜的 PIN1 磷酸化对 BFA 处理的敏感性不同，表明不同的蛋白激酶或运输机制参与了 PIN1 磷酸化控制。我们得出结论，磷酸位点偏好不足以解释 D6PK 和 PID 对 PIN1 极性的差异影响，并建议需要更复杂的模型来解释 PID 的影响。
The directional distribution of the phytohormone auxin is essential for plant development. Directional auxin transport is mediated by the polarly distributed PIN-FORMED (PIN) auxin efflux carriers. We have previously shown that efficient PIN1-mediated auxin efflux requires activation through phosphorylation at the four serines S1-S4 in Arabidopsis thaliana. The Brefeldin A (BFA)-sensitive D6 PROTEIN KINASE (D6PK) and the BFA-insensitive PINOID (PID) phosphorylate and activate PIN1 through phosphorylation at all four phosphosites. PID, but not D6PK, can also induce PIN1 polarity shifts, seemingly through phosphorylation at S1-S3. The differential effects of D6PK and PID on PIN1 polarity had so far been attributed to their differential phosphosite preference for the four PIN1 phosphosites. We have mapped PIN1 phosphorylation at S1-S4 in situ using phosphosite-specific antibodies. We detected phosphorylation at PIN1 phosphosites at the basal (rootward) as well as the apical (shootward) plasma membrane in different root cell types, in embryos, and shoot apical meristems. Thereby, PIN1 phosphorylation at all phosphosites generally followed the predominant PIN1 distribution but was not restricted to specific polar sides of the cells. PIN1 phosphorylation at the basal and apical plasma membrane was differentially sensitive to BFA treatments, suggesting the involvement of different protein kinases or trafficking mechanisms in PIN1 phosphorylation control. We conclude that phosphosite preferences are not sufficient to explain the differential effects of D6PK and PID on PIN1 polarity, and suggest that a more complex model is needed to explain the effects of PID.