Lipid Segregation and Membrane Budding Induced by the Peripheral Membrane Binding Protein Annexin A2
Lipid Segregation and Membrane Budding Induced by the Peripheral Membrane Binding Protein Annexin A2
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DOI：
10.1074/jbc.m113.474023
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发表时间：
2013-08-23
影响因子：
4.8
通讯作者：
Gerke, Volker
中科院分区：
文献类型：
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作者：
Druecker, Patrick;Pejic, Milena;Gerke, Volker
动态膜微区的形成是许多信号转导和膜转运事件中的重要现象。它是由膜脂和膜结合蛋白的固有性质驱动的。在这里，我们分析了一种外周结合的膜蛋白Annexin A2(AnxA2)诱导复杂脂质成分的巨大单层囊泡(GUV)形成富含磷脂酰肌醇4，5-二磷酸(PI(4，5)P-2)结构域的能力。AnxA2是一种胞质蛋白，能与PI(4，5)P-2和其他酸性磷脂结合，依赖于钙离子，参与胞吞和胞吐的细胞膜动力学过程。我们发现，AnxA2与GUV结合后，导致脂质相分离，PI(4，5)P-2、胆固醇和糖鞘糖脂重新聚集到更大的簇中。这一特性适用于全长单体蛋白，这是一种包含C-末端蛋白核心域的突变衍生物，也适用于AnxA2与其细胞内结合伙伴S100A10形成的异四聚体复合体。所有诱导PI(4，5)P-2聚集的AnxA2衍生物也能够在相邻GUV的富含PI(4，5)P-2的微区之间形成互联。此外，它们还可以诱导富含PI(4，5)P-2的膜凹陷，并将这些膜结构域向内萌发到GUV的管腔中。这种向内的囊泡形成是AnxA2所特有的，与其他PI(4，5)P-2结合蛋白(如磷脂酶C delta1的Pleckstrin同源(PH)结构域)不同。综上所述，我们的结果表明，AnxA2等膜联蛋白可以有效地诱导脂质分离后的膜变形，这可能是膜联蛋白在膜转运中作用的一个机制。
The formation of dynamic membrane microdomains is an important phenomenon in many signal transduction and membrane trafficking events. It is driven by intrinsic properties of membrane lipids and integral as well as membrane-associated proteins. Here we analyzed the ability of one peripherally associated membrane protein, annexin A2 (AnxA2), to induce the formation of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P-2)-rich domains in giant unilamellar vesicles (GUVs) of complex lipid composition. AnxA2 is a cytosolic protein that can bind PI(4,5)P-2 and other acidic phospholipids in a Ca2+-dependent manner and that has been implicated in cellular membrane dynamics in endocytosis and exocytosis. We show that AnxA2 binding to GUVs induces lipid phase separation and the recruitment of PI(4,5)P-2, cholesterol and glycosphingolipids into larger clusters. This property is observed for the full-length monomeric protein, a mutant derivative comprising the C-terminal protein core domain and for AnxA2 residing in a heterotetrameric complex with its intracellular binding partner S100A10. All AnxA2 derivatives inducing PI(4,5)P-2 clustering are also capable of forming interconnections between PI(4,5)P-2-rich microdomains of adjacent GUVs. Furthermore, they can induce membrane indentations rich in PI(4,5)P-2 and inward budding of these membrane domains into the lumen of GUVs. This inward vesiculation is specific for AnxA2 and not shared with other PI(4,5)P-2-binding proteins such as the pleckstrin homology (PH) domain of phospholipase C delta 1. Together our results indicate that annexins such as AnxA2 can efficiently induce membrane deformations after lipid segregation, a mechanism possibly underlying annexin functions in membrane trafficking.