Crystal structure of a human plasma membrane phospholipid flippase
Crystal structure of a human plasma membrane phospholipid flippase
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DOI：
10.1074/jbc.ra120.014144
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发表时间：
2020-07-24
影响因子：
4.8
通讯作者：
Abe, Kazuhiro
中科院分区：
文献类型：
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作者：
Nakanishi, Hanayo;Irie, Katsumasa;Abe, Kazuhiro
ATP 11 C是P4-ATP酶翻转酶的成员，负责将磷脂酰丝氨酸从质膜外叶转移到质膜内叶，并维持磷脂酰丝氨酸在活细胞中的不对称分布。我们目前的晶体结构的人质膜翻转酶，ATP 11 C？CDC 50 A复合物，处于稳定的E2 P构象。该结构揭示了一个深的纵向裂缝沿着跨膜螺旋继续从细胞表面的磷脂闭塞网站在中间的膜。我们观察到，扩展的裂缝外质侧是开放的，因此，复杂的是在一个向外开放的E2 P状态，类似于最近报道的冷冻EM结构的酵母翻转酶Drs 2 p？Cdc 50 p复合物。我们注意到额外的密度，最有可能结合磷脂酰丝氨酸，在裂缝和其延伸到细胞外的一面。一个是接近磷脂酰丝氨酸闭塞网站，如以前报道的人ATP 8A 1？CDC 50 A复合物，另一个在双层外质小叶表面的空腔中。取代在任何一个结合位点或沿着它们之间的路径损害特定的ATP酶和运输活动。这些结果提供的证据表明，所观察到的裂缝是管道沿着，磷脂酰丝氨酸从外叶到其在膜中的闭塞部位，并建议外质腔是重要的磷脂识别。他们还产生的见解磷脂酰丝氨酸是如何从质膜的外叶纳入跨膜。
ATP11C, a member of the P4-ATPase flippase, translocates phosphatidylserine from the outer to the inner plasma membrane leaflet, and maintains the asymmetric distribution of phosphatidylserine in the living cell. We present the crystal structures of a human plasma membrane flippase, ATP11C?CDC50A complex, in a stabilized E2P conformation. The structure revealed a deep longitudinal crevice along transmembrane helices continuing from the cell surface to the phospholipid occlusion site in the middle of the membrane. We observed that the extension of the crevice on the exoplasmic side is open, and the complex is therefore in an outward-open E2P state, similar to a recently reported cryo-EM structure of yeast flippase Drs2p?Cdc50p complex. We noted extra densities, most likely bound phosphatidylserines, in the crevice and in its extension to the extracellular side. One was close to the phosphatidylserine occlusion site as previously reported for the human ATP8A1?CDC50A complex, and the other in a cavity at the surface of the exoplasmic leaflet of the bilayer. Substitutions in either of the binding sites or along the path between them impaired specific ATPase and transport activities. These results provide evidence that the observed crevice is the conduit along that phosphatidylserine traverses from the outer leaflet to its occlusion site in the membrane and suggest that the exoplasmic cavity is important for phospholipid recognition. They also yield insights into how phosphatidylserine is incorporated from the outer leaflet of the plasma membrane into the transmembrane.