Tetramerization and ATP binding by a protein comprising the A, B, and C domains of rat synapsin I
Tetramerization and ATP binding by a protein comprising the A, B, and C domains of rat synapsin I
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DOI：
10.1074/jbc.m312015200
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发表时间：
2004-03-19
影响因子：
4.8
通讯作者：
Deisenhofer, J
中科院分区：
文献类型：
--
作者：
Brautigam, CA;Chelliah, Y;Deisenhofer, J
突触蛋白是一种多结构域蛋白，在脊椎动物中对调节神经递质释放至关重要。在本研究中，两个晶体结构的C结构域的大鼠突触蛋白I（rSynI-C）在复杂的Ca 2+和ATP显示，这种蛋白质可以形成一个四聚体和一个灵活的环（“多功能环”）接触绑定ATP。对包含大鼠突触蛋白I的A、B和C结构域的蛋白质（rSynI-ABC）进行进一步的实验。在速度沉降和尺寸排阻色谱实验中观察到ATP稳定的rSynI-ABC四聚体。这些流体动力学结果还表明，A和B结构域存在于一个扩展的构象。ATP结合野生型和突变型rSynI-ABC的量热测量表明，多功能环和交叉四聚体接触是重要的ATP结合。这些证据支持突触蛋白I是一种利用ATP的四聚体蛋白质的观点，它由具有柔性的延伸N末端的单体组成。
Synapsins are multidomain proteins that are critical for regulating neurotransmitter release in vertebrates. In the present study, two crystal structures of the C domain of rat synapsin I (rSynI-C) in complex with Ca2+ and ATP reveal that this protein can form a tetramer and that a flexible loop ( the "multifunctional loop") contacts bound ATP. Further experiments were carried out on a protein comprising the A, B, and C domains of rat synapsin I (rSynI-ABC). An ATP-stabilized tetramer of rSynI-ABC is observed during velocity sedimentation and size-exclusion chromatographic experiments. These hydrodynamic results also indicate that the A and B domains exist in an extended conformation. Calorimetric measurements of ATP binding to wild-type and mutant rSynI-ABC demonstrate that the multifunctional loop and a cross-tetramer contact are important for ATP binding. The evidence supports a view of synapsin I as an ATP-utilizing, tetrameric protein made up of monomers that have a flexible, extended N terminus.