Regulation of clathrin-mediated endocytosis by hierarchical allosteric activation of AP2.
Regulation of clathrin-mediated endocytosis by hierarchical allosteric activation of AP2.
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DOI：
10.1083/jcb.201608071
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发表时间：
2017-01-02
期刊：
影响因子：
--
通讯作者：
Schmid SL
中科院分区：
文献类型：
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作者：
Kadlecova Z;Spielman SJ;Loerke D;Mohanakrishnan A;Reed DK;Schmid SL
接合子AP2对于网格蛋白介导的内吞作用的起始是必需的。Kadlecova等人描述了AP2与磷脂酰肌醇脂质和货物相互作用的功能层次，以及它们与活细胞中网格蛋白包被的核坑成核和成熟的不同步骤的关系。网格蛋白介导的内吞作用（CME）的关键起始阶段决定了内吞作用发生的地点和时间。异四聚体接头蛋白2 （AP2）复合物启动网格蛋白包覆坑（CCP）组装，在响应磷脂酰肌醇4,5-二磷酸（PIP2）和多位点货物结合的构象变化中被激活。然而，相互作用的功能层次以及这些构象变化如何与活细胞中CCP形成的不同步骤相关仍然未知。我们使用定量活细胞分析来测量离散的CME早期阶段，并展示了顺序的、变构调节的构象变化如何激活AP2来驱动新生ccp的成核和随后的稳定。我们的数据表明，含有Yxxφ基序而非二苯环基序的产物在AP2激活和CCP成核的早期阶段起关键作用。有趣的是，这些货物和PIP2的相互作用在酵母中并不保守。因此，我们推测AP2已演变为协调CCP形成和货物分拣的关键调控节点，并确保CME的高时空调控。
The adaptor AP2 is required for initiation of clathrin-mediated endocytosis. Kadlecova et al. delineate the functional hierarchy of AP2 interactions with phosphatidylinositol lipids and cargo and their relationship to distinct steps in clathrin-coated pit nucleation and maturation in living cells. The critical initiation phase of clathrin-mediated endocytosis (CME) determines where and when endocytosis occurs. Heterotetrameric adaptor protein 2 (AP2) complexes, which initiate clathrin-coated pit (CCP) assembly, are activated by conformational changes in response to phosphatidylinositol-4,5-bisphosphate (PIP2) and cargo binding at multiple sites. However, the functional hierarchy of interactions and how these conformational changes relate to distinct steps in CCP formation in living cells remains unknown. We used quantitative live-cell analyses to measure discrete early stages of CME and show how sequential, allosterically regulated conformational changes activate AP2 to drive both nucleation and subsequent stabilization of nascent CCPs. Our data establish that cargoes containing Yxxφ motif, but not dileucine motif, play a critical role in the earliest stages of AP2 activation and CCP nucleation. Interestingly, these cargo and PIP2 interactions are not conserved in yeast. Thus, we speculate that AP2 has evolved as a key regulatory node to coordinate CCP formation and cargo sorting and ensure high spatial and temporal regulation of CME.