Myosin binding protein C positioned to play a key role in regulation of muscle contraction: structure and interactions of domain C1.
Myosin binding protein C positioned to play a key role in regulation of muscle contraction: structure and interactions of domain C1.
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DOI：
10.1016/j.jmb.2008.09.065
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发表时间：
2008-12-19
影响因子：
5.6
通讯作者：
Pfuhl, Mark
中科院分区：
文献类型：
--
作者：
Ababou, Abdessamad;Rostkova, Elena;Mistry, Shreena;Le Masurier, Clare;Gautel, Mathias;Pfuhl, Mark
肌球蛋白结合蛋白C（MyBP-C）是一种参与调节肌肉收缩的粗丝蛋白。MyBP-C基因突变是肥厚型心肌病的第二大常见原因。MyBP-C通过两个结合位点与肌球蛋白结合，一个在其C-末端，另一个在其N-末端。N-末端结合位点由通过柔性接头连接的免疫球蛋白结构域C1和C2组成，以磷酸化调节的方式与肌球蛋白的S2片段相互作用。据推测，MyBP-C的功能是作为一个系链，将S1头固定在静止位置，磷酸化释放S1头进入活性状态。在这里，我们报告结构域C1的结构和结合特性。使用定点诱变和NMR相互作用实验的组合，我们确定了结构域C1的结合位点在紧邻的S1-S2铰链，非常接近轻链。此外，我们确定了一个锌结合位点上的结构域C1在接近的S2结合位点。其锌结合亲和力（Kd约为10-20 μM）可能不足以产生生理效应。然而，家族性肥厚性心肌病相关突变的锌配体之一，谷氨酰胺210组氨酸，将显着增加的结合亲和力，这表明这种突变可能会影响S2结合。C1结合位点与铰链、轻链和S1头部的紧密接近也为最近的观察结果提供了解释，即（a）不能作为系链的MyBP-C的较短片段仍然对肌动球蛋白ATP酶有影响，以及（B）为什么磷酸化野生型小鼠和MyBP-C敲除小鼠中的肌球蛋白头部位置如此不同：与S1-S2铰链结合的结构域C1能够操纵S1头部位置，从而在没有系链的情况下影响力的产生。预期C1的潜在广泛的额外相互作用将其保持在适当位置，而磷酸化使C1-C2接头和结构域C2移位。因此，肌球蛋白的头部总是连接到一个具有磷酸化依赖性长度调节的系链上。
Myosin binding protein C (MyBP-C) is a thick filament protein involved in the regulation of muscle contraction. Mutations in the gene for MyBP-C are the second most frequent cause of hypertrophic cardiomyopathy. MyBP-C binds to myosin with two binding sites, one at its C-terminus and another at its N-terminus. The N-terminal binding site, consisting of immunoglobulin domains C1 and C2 connected by a flexible linker, interacts with the S2 segment of myosin in a phosphorylation-regulated manner. It is assumed that the function of MyBP-C is to act as a tether that fixes the S1 heads in a resting position and that phosphorylation releases the S1 heads into an active state. Here, we report the structure and binding properties of domain C1. Using a combination of site-directed mutagenesis and NMR interaction experiments, we identified the binding site of domain C1 in the immediate vicinity of the S1–S2 hinge, very close to the light chains. In addition, we identified a zinc binding site on domain C1 in close proximity to the S2 binding site. Its zinc binding affinity (Kd of approximately 10–20 μM) might not be sufficient for a physiological effect. However, the familial hypertrophic cardiomyopathy-related mutation of one of the zinc ligands, glutamine 210 to histidine, will significantly increase the binding affinity, suggesting that this mutation may affect S2 binding. The close proximity of the C1 binding site to the hinge, the light chains and the S1 heads also provides an explanation for recent observations that (a) shorter fragments of MyBP-C unable to act as a tether still have an effect on the actomyosin ATPase and (b) as to why the myosin head positions in phosphorylated wild-type mice and MyBP-C knockout mice are so different: Domain C1 bound to the S1–S2 hinge is able to manipulate S1 head positions, thus influencing force generation without tether. The potentially extensive extra interactions of C1 are expected to keep it in place, while phosphorylation dislodges the C1–C2 linker and domain C2. As a result, the myosin heads would always be attached to a tether that has phosphorylation-dependent length regulation.
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DOI：
10.1073/pnas.0606741103
发表时间：
2006-11-21
影响因子：
11.1
作者：
Blankenfeldt, Wulf;Thoma, Nicolas H.;Schlichting, Ilme
通讯作者：
Schlichting, Ilme
影响因子：
3.4
作者：
Kensler, Robert W.;Harrist, Samantha P.
通讯作者：
Harrist, Samantha P.
影响因子：
5.6
作者：
Gruen, M;Gautel, M
通讯作者：
Gautel, M
影响因子：
3.5
作者：
Gruen, M;Prinz, H;Gautel, M
通讯作者：
Gautel, M
影响因子：
3.9
作者：
Blindauer, Claudia A.
通讯作者：
Blindauer, Claudia A.