Dilated cardiomyopathy mutation in beta-cardiac myosin enhances actin activation of the power stroke and phosphate release.
Dilated cardiomyopathy mutation in beta-cardiac myosin enhances actin activation of the power stroke and phosphate release.
复制标题
扩张型心肌病β-心肌肌球蛋白突变增强了动力冲程的肌动蛋白激活和磷酸盐释放。
DOI：
10.1101/2023.11.10.566646
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Yengo,ChristopherM
中科院分区：
文献类型：
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作者：
Bodt,SkylarML;Ge,Jinghua;Ma,Wen;Rasicci,DavidV;Desetty,Rohini;McCammon,JAndrew;Yengo,ChristopherM
人类β-心肌肌球蛋白（M2β）的遗传突变可导致严重形式的心力衰竭。M2β中的E525 K突变与扩张型心肌病（DCM）相关，并被发现稳定二聚体重肌球蛋白中的相互作用头基序（IHM）和自抑制超松弛（SRX）状态。然而，在单体M2β亚片段1（S1）中，我们发现E525 K增强（3倍）最大稳态肌动蛋白激活的ATP酶活性（kcat），并降低（8倍）ATP酶达到最大值一半时的肌动蛋白浓度（KATP酶）。我们还发现，在30 μM肌动蛋白时，肌动蛋白激活的动力冲程和磷酸盐释放速率常数增加了2至4倍，总体上使占空比增加了3倍。负荷运动试验表明，增强的内在运动活性转化为M2β S1中的整体力增加。谷氨酸525位于所谓的激活环中的肌动蛋白结合区附近，是高度保守的，并预测与中继螺旋中的另一个保守残基（赖氨酸484）形成盐桥。增强采样分子动力学模拟预测，电荷反转突变破坏E525-K484盐桥，诱导构象更灵活的中继螺旋和广泛的磷酸盐释放隧道。我们的研究结果突出了一个高度保守的变构途径与肌动蛋白激活的功率中风和磷酸盐释放，并建议一个重要的功能，自我抑制的IHM是防止该地区的肌球蛋白与肌动蛋白相互作用。E525 K突变稳定IHM的能力可能超过了增强的内在运动特性，这可能是触发DCM发病机制的关键。
Inherited mutations in human beta-cardiac myosin (M2β) can lead to severe forms of heart failure. The E525K mutation in M2β is associated with dilated cardiomyopathy (DCM) and was found to stabilize the interacting heads motif (IHM) and autoinhibited super-relaxed (SRX) state in dimeric heavy meromyosin. However, in monomeric M2β subfragment 1 (S1) we found that E525K enhances (threefold) the maximum steady-state actin-activated ATPase activity (kcat) and decreases (eightfold) the actin concentration at which ATPase is one-half maximal (KATPase). We also found a twofold to fourfold increase in the actin-activated power stroke and phosphate release rate constants at 30 μM actin, which overall enhanced the duty ratio threefold. Loaded motility assays revealed that the enhanced intrinsic motor activity translates to increased ensemble force in M2β S1. Glutamate 525, located near the actin binding region in the so-called activation loop, is highly conserved and predicted to form a salt bridge with another conserved residue (lysine 484) in the relay helix. Enhanced sampling molecular dynamics simulations predict that the charge reversal mutation disrupts the E525-K484 salt bridge, inducing conformations with a more flexible relay helix and a wide phosphate release tunnel. Our results highlight a highly conserved allosteric pathway associated with actin activation of the power stroke and phosphate release and suggest an important feature of the autoinhibited IHM is to prevent this region of myosin from interacting with actin. The ability of the E525K mutation to stabilize the IHM likely overrides the enhanced intrinsic motor properties, which may be key to triggering DCM pathogenesis.