GTP-dependent packing of a three-helix bundle is required for atlastin-mediated fusion
GTP-dependent packing of a three-helix bundle is required for atlastin-mediated fusion
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DOI：
10.1073/pnas.1106421108
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发表时间：
2011-09-27
影响因子：
11.1
通讯作者：
Daga, Andrea
中科院分区：
文献类型：
--
作者：
Pendin, Diana;Tosetto, Jessica;Daga, Andrea
调节atlastin介导的膜融合的机制尚不清楚。在这里，我们证明了一个三螺旋束（3HB）内的中间域是需要寡聚化。这些螺旋内的核心疏水残基的突变通过阻止膜束缚和随后的融合而使atlastin功能失活。GTP结合诱导的构象变化，重新定位的GTP酶域相对于3HB，以允许自关联，但水解GTP的能力是完全融合所需的，这表明核苷酸结合和水解发挥不同的作用。atlastin的寡聚化刺激其水解GTP的能力，并且释放的能量驱动脂质双层合并。阻止atlastin自身结合的突变也消除了GT3活性的寡聚化依赖性刺激。此外，增加从膜的atlastin复合物形成的距离抑制融合，这表明该距离是至关重要的atlastin促进融合。
The mechanisms governing atlastin-mediated membrane fusion are unknown. Here we demonstrate that a three-helix bundle (3HB) within the middle domain is required for oligomerization. Mutation of core hydrophobic residues within these helices inactivates atlastin function by preventing membrane tethering and the subsequent fusion. GTP binding induces a conformational change that reorients the GTPase domain relative to the 3HB to permit self-association, but the ability to hydrolyze GTP is required for full fusion, indicating that nucleotide binding and hydrolysis play distinct roles. Oligomerization of atlastin stimulates its ability to hydrolyze GTP, and the energy released drives lipid bilayer merger. Mutations that prevent atlastin self-association also abolish oligomerization-dependent stimulation of GTPase activity. Furthermore, increasing the distance of atlastin complex formation from the membrane inhibits fusion, suggesting that this distance is crucial for atlastin to promote fusion.