Computational Methods Elucidate Consequences of Mutations and Post-translational Modifications on Troponin I Effective Concentration to Troponin C.
Computational Methods Elucidate Consequences of Mutations and Post-translational Modifications on Troponin I Effective Concentration to Troponin C.
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DOI：
10.1021/acs.jpcb.1c03844
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发表时间：
2021-07-15
期刊：
影响因子：
--
通讯作者：
Lindert S
中科院分区：
文献类型：
--
作者：
Cool AM;Lindert S
Ca2+ 与心肌肌钙蛋白 C (cTnC) 结合会引起构象变化，从而暴露出疏水性补片 (cTnCHP)，以便与 cTnI 开关肽 (cTnISP) 结合，最终导致心脏收缩。抑制肽 (cTnIIP) 连接在 cTnISP 的 N 末端，充当 cTnISP 与肌钙蛋白复合物其余部分的系链。由于这种束缚性质，cTnISP 保持在疏水斑块区域附近，导致 cTnCHP 的 cTnISP 的“有效浓度”升高。据推测，cTnIIP 区域的突变会影响 cTnISP“发现”疏水斑块的能力，从而导致心脏正常收缩能力的改变，从而导致疾病。我们使用包含肌钙蛋白所有三个亚基：C、I 和 T (cTnT) 的模型，使用肌钙蛋白复合物的分子动力学 (MD) 模拟来测试这一假设。我们开发了一些方法，使我们能够从模拟中定量测量 cTnISP 的有效浓度。当从系统中移除 cTnIIP 时，观察到 cTnISP 有效浓度显着降低，这显示了系留 cTnISP 的重要性。通过加速MD方法，我们提出系留cTnISP的最小有效浓度约为21mM。通过 PKC 介导的 T143 磷酸化对 cTnIIP 进行修饰可显着增加 cTnISP 的估计有效浓度，帮助 cTnISP 更有效地找到 cTnCHP，并与天然模型相比保持 cTnIIP 的相对形状。所有这些数据表明 pT143 可能能够帮助促进 cTnISP 与 cTnCHP 的结合。然后，我们测试了 cTnIIP 区域内的 6 个突变，这些突变被称为 cTnC Ca2+ 敏化突变，并且与心肌病有关。我们没有观察到引入这些突变后有效浓度显着降低，但我们确实观察到与天然相比，cTnIIP 区域的灵活性和动态变化性有所增加。我们的观察使我们推测这些心肌病突变影响 Ca2+ 敏感性的机制是通过改变 cTnISP 从疏水性斑块的解离率。
Ca2+ binding to cardiac troponin C (cTnC) causes a conformational shift that exposes a hydrophobic patch (cTnCHP) for binding of the cTnI switch peptide (cTnISP), ultimately resulting in contraction of the heart. The inhibitory peptide (cTnIIP), attached at the N-terminal end of the cTnISP, serves as a tether for the cTnISP to the rest of the troponin complex. Due to this tethered nature, the cTnISP remains within proximity of the hydrophobic patch region, resulting in the cTnCHP experiencing an elevated “effective concentration” of the cTnISP. Mutations to the cTnIIP region have been hypothesized to cause disease by effecting the ability of the cTnISP to ‘find’ the hydrophobic patch, resulting in alterations to the heart’s ability to contract normally. We tested this hypothesis using molecular dynamics (MD) simulations of the troponin complex using a model that contained all three subunits of troponin: C, I, and T (cTnT). We developed methods that allowed us to quantitatively measure the effective concentration of the cTnISP from the simulations. A significant reduction in cTnISP effective concentration was observed when the cTnIIP was removed from the system, showcasing the importance of a tethered cTnISP. Through accelerated MD methods, we proposed the minimum effective concentration of a tethered cTnISP to be approximately 21mM. Modification of the cTnIIP via PKC mediated phosphorylation of T143 was shown to significantly increase the estimated effective concentration of cTnISP, help the cTnISP find the cTnCHP more effectively, and maintain the relative shape of the cTnIIP when compared to the native model. All of this data indicates that pT143 may be able to help promote binding of cTnISP to the cTnCHP. We then tested six mutations within the cTnIIP region that are known cTnC Ca2+ sensitizing mutations, and have been linked with cardiomyopathy. We did not observe a significant reduction in effective concentration upon introduction of these mutations, however we did observe increased variability in the flexibility and dynamics of the cTnIIP region when compared to native. Our observations led us to hypothesize that the mechanism by which these cardiomyopathic mutations effect Ca2+ sensitivity is by altering the off rate of cTnISP from the hydrophobic patch.
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影响因子：
5.6
作者：
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DOI：
10.1016/s1044-0305(01)00317-8
发表时间：
2001-12-01
影响因子：
3.2
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通讯作者：
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