Structural basis of Rab5-Rabaptin5 interaction in endocytosis
Structural basis of Rab5-Rabaptin5 interaction in endocytosis
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DOI：
10.1038/nsmb832
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发表时间：
2004-10-01
影响因子：
16.8
通讯作者：
Zhang, XJC
中科院分区：
文献类型：
--
作者：
Zhu, GY;Zhai, P;Zhang, XJC
Rab 5是一个小的GT3，调节早期内体融合。我们在这里提出的晶体结构的Rab 5 GTP结构域的复合物与GTP类似物和效应Rabaptin 5的C-末端结构域。这些蛋白质形成二联体对称Rab 5-Rabaptin 5（2）-Rab 5三元复合物，在中间具有平行卷曲螺旋Rabaptin 5同源二聚体。两个Rab 5分子使用它们的开关和开关间区域独立地结合Rabaptin 5二聚体。结合不涉及Rab互补决定区。我们还提出了两种不同形式的GDP-Rab 5复合物的晶体结构，这两种复合物都与Rabaptin 5结合不相容。一个有一个错位和无序的开关I，但几乎完整的开关II，而另一个有它的β-片层和两个开关区域重组。生物化学和功能分析表明，晶体学观察Rab 5-Rabaptin 5复合物也存在于溶液中，并且通过突变破坏该复合物消除了内体融合。
Rab5 is a small GTPase that regulates early endosome fusion. We present here the crystal structure of the Rab5 GTPase domain in complex with a GTP analog and the C-terminal domain of effector Rabaptin5. The proteins form a dyad-symmetric Rab5-Rabaptin5(2)-Rab5 ternary complex with a parallel coiled-coil Rabaptin5 homodimer in the middle. Two Rab5 molecules bind independently to the Rabaptin5 dimer using their switch and interswitch regions. The binding does not involve the Rab complementarity-determining regions. We also present the crystal structures of two distinct forms of GDP-Rab5 complexes, both of which are incompatible with Rabaptin5 binding. One has a dislocated and disordered switch I but a virtually intact switch II, whereas the other has its beta-sheet and both switch regions reorganized. Biochemical and functional analyses show that the crystallographically observed Rab5-Rabaptin5 complex also exists in solution, and disruption of this complex by mutation abrogates endosome fusion.