A PP6-Type Phosphatase Holoenzyme Directly Regulates PIN Phosphorylation and Auxin Efflux in Arabidopsis
A PP6-Type Phosphatase Holoenzyme Directly Regulates PIN Phosphorylation and Auxin Efflux in Arabidopsis
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DOI：
10.1105/tpc.112.098905
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发表时间：
2012-06-01
期刊：
影响因子：
11.6
通讯作者：
Wang, Haiyang
中科院分区：
文献类型：
--
作者：
Dai, Mingqiu;Zhang, Chen;Wang, Haiyang
植物激素生长素的定向运输依赖于PIN形成的生长素流出蛋白的磷酸化状态和极性定位。虽然PINIOD（PID）激酶直接参与PIN蛋白的磷酸化，但使PIN蛋白去磷酸化的磷酸酶全酶复合物仍然难以捉摸。在这里，我们证明，突变同时破坏拟南芥FyPP 1（光敏色素相关的丝氨酸/苏氨酸蛋白磷酸酶1）和FyPP 3，两个同源基因编码的催化亚基蛋白磷酸酶6（PP 6）的功能，导致磷酸化PIN蛋白的积累升高，与亚细胞PIN定位的基底到顶端的转变。PIN极性的变化导致根向基生长素运输增加和严重缺陷，包括短根、少侧根、有缺陷的柱细胞、根分生组织塌陷、异常子叶（小的、杯状的或融合的子叶）和改变的叶序。我们的分子、生化和遗传数据支持FyPP 1/3、SAL（SAPS结构域样）和PP 2AA蛋白（RCN 1 [萘酞酸中的根卷曲1]或PP 2AA 1、PP 2AA 2和PP 2AA 3）物理相互作用形成新型PP 6型异源三聚体全酶复合物的观点。我们还表明，FyPP 1/3，SAL，和PP 2AA与PIN蛋白的一个子集，SAL的相互作用的强度取决于PIN的磷酸化状态。因此，拟南芥PP 6型磷酸酶全酶与PID拮抗作用，通过直接调节PIN磷酸化来指导生长素运输极性和植物发育。
The directional transport of the phytohormone auxin depends on the phosphorylation status and polar localization of PIN-FORMED (PIN) auxin efflux proteins. While PINIOD (PID) kinase is directly involved in the phosphorylation of PIN proteins, the phosphatase holoenzyme complexes that dephosphorylate PIN proteins remain elusive. Here, we demonstrate that mutations simultaneously disrupting the function of Arabidopsis thaliana FyPP1 (for Phytochrome-associated serine/threonine protein phosphatase1) and FyPP3, two homologous genes encoding the catalytic subunits of protein phosphatase6 (PP6), cause elevated accumulation of phosphorylated PIN proteins, correlating with a basal-to-apical shift in subcellular PIN localization. The changes in PIN polarity result in increased root basipetal auxin transport and severe defects, including shorter roots, fewer lateral roots, defective columella cells, root meristem collapse, abnormal cotyledons (small, cup-shaped, or fused cotyledons), and altered leaf venation. Our molecular, biochemical, and genetic data support the notion that FyPP1/3, SAL (for SAPS DOMAIN-LIKE), and PP2AA proteins (RCN1 [for ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID1] or PP2AA1, PP2AA2, and PP2AA3) physically interact to form a novel PP6-type heterotrimeric holoenzyme complex. We also show that FyPP1/3, SAL, and PP2AA interact with a subset of PIN proteins and that for SAL the strength of the interaction depends on the PIN phosphorylation status. Thus, an Arabidopsis PP6-type phosphatase holoenzyme acts antagonistically with PID to direct auxin transport polarity and plant development by directly regulating PIN phosphorylation.