Structural basis for endothelial nitric oxide synthase binding to calmodulin
Structural basis for endothelial nitric oxide synthase binding to calmodulin
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DOI：
10.1093/emboj/cdg078
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发表时间：
2003-02-17
期刊：
影响因子：
11.4
通讯作者：
Getzoff, ED
中科院分区：
文献类型：
--
作者：
Aoyagi, M;Arvai, AS;Getzoff, ED
一氧化氮合酶（NOS）在体内由钙离子传感器蛋白钙调素（CaM）精细调节，以控制NO（一种关键信号分子和细胞毒素）的产生。尽管进行了广泛的研究，但CaM对NOS同工酶的差异激活仍然是个谜。在这里，钙离子负载钙调素结合到一个20个残基的肽，包括内皮型一氧化氮合酶（eNOS）钙调素结合区的晶体结构建立其各自的构象和分子间的相互作用，并建议的基础上同工酶特异性的差异。α-螺旋eNOS肽通过广泛的疏水相互作用以反平行方向与CaM结合。独特的NOS相互作用发生在：（i）CaM柔性中心连接体，解释其在NOS激活中的重要性;和（ii）CaM C-末端，解释NOS特异性需要在位置144处的大体积疏水残基。这种结合模式扩展了CaM介导的激活机制，解释了Thr 495磷酸化导致的eNOS失活，并暗示了诱导型NOS的Ca 2+独立性中的特定疏水残基。
The enzyme nitric oxide synthase (NOS) is exquisitely regulated in vivo by the Ca2+ sensor protein calmodulin (CaM) to control production of NO, a key signaling molecule and cytotoxin. The differential activation of NOS isozymes by CaM has remained enigmatic, despite extensive research. Here, the crystallographic structure of Ca2+-loaded CaM bound to a 20 residue peptide comprising the endothelial NOS (eNOS) CaM-binding region establishes their individual conformations and intermolecular interactions, and suggests the basis for isozyme-specific differences. The alpha-helical eNOS peptide binds in an antiparallel orientation to CaM through extensive hydrophobic interactions. Unique NOS interactions occur with: (i) the CaM flexible central linker, explaining its importance in NOS activation; and (ii) the CaM C-terminus, explaining the NOS-specific requirement for a bulky, hydrophobic residue at position 144. This binding mode expands mechanisms for CaM-mediated activation, explains eNOS deactivation by Thr495 phosphorylation, and implicates specific hydrophobic residues in the Ca2+ independence of inducible NOS.