Randall Centre for Cell and Molecular Biophysics; and British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, United Kingdom.
Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY, USA.
Nat Commun. 2024 Jun 14;15(1):5111. doi: 10.1038/s41467-024-49408-5.
Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) is a determinant of cardiac myofilament function. Although cMyBP-C phosphorylation by various protein kinases has been extensively studied, the influence of protein phosphatases on cMyBP-C's multiple phosphorylation sites has remained largely obscure. Here we provide a detailed biochemical characterization of cMyBP-C dephosphorylation by protein phosphatases 1 and 2 A (PP1 and PP2A), and develop an integrated kinetic model for cMyBP-C phosphorylation using data for both PP1, PP2A and various protein kinases known to phosphorylate cMyBP-C. We find strong site-specificity and a hierarchical mechanism for both phosphatases, proceeding in the opposite direction of sequential phosphorylation by potein kinase A. The model is consistent with published data from human patients and predicts complex non-linear cMyBP-C phosphorylation patterns that are validated experimentally. Our results suggest non-redundant roles for PP1 and PP2A under both physiological and heart failure conditions, and emphasize the importance of phosphatases for cMyBP-C regulation.
肌球蛋白结合蛋白 C（cMyBP-C）的磷酸化是心肌肌丝功能的决定因素。尽管已经广泛研究了各种蛋白激酶对 cMyBP-C 的磷酸化作用，但蛋白磷酸酶对 cMyBP-C 的多个磷酸化位点的影响在很大程度上仍不清楚。在这里，我们详细描述了蛋白磷酸酶 1 和 2A（PP1 和 PP2A）对 cMyBP-C 的去磷酸化作用，并利用已知可磷酸化 cMyBP-C 的 PP1、PP2A 和各种蛋白激酶的数据，为 cMyBP-C 的磷酸化建立了一个综合的动力学模型。我们发现这两种磷酸酶具有很强的位点特异性和分级机制，与蛋白激酶 A 的顺序磷酸化方向相反。该模型与来自人类患者的已发表数据一致，并预测了实验验证的复杂非线性 cMyBP-C 磷酸化模式。我们的研究结果表明，在生理和心力衰竭条件下，PP1 和 PP2A 具有非冗余作用，并强调了磷酸酶在 cMyBP-C 调节中的重要性。
