Dynamics of β-cardiac myosin between the super-relaxed and disordered-relaxed states.

IF 4 2区 生物学 Q2 BIOCHEMISTRY & MOLECULAR BIOLOGY
Robert C Cail, Faviolla A Baez-Cruz, Donald A Winkelmann, Yale E Goldman, E Michael Ostap
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引用次数: 0

Abstract

The super-relaxed (SRX) state of myosin ATPase activity is critical for striated muscle function, and its dysregulation is linked to cardiomyopathies. It is unclear whether the SRX state exchanges readily with the disordered-relaxed (DRX) state, and whether the SRX state directly corresponds to the folded back interacting-head motif (IHM). Using recombinant β-cardiac heavy meromyosin (HMM) and subfragment 1 (S1), which cannot form the IHM, we show that the SRX and DRX populations transition at a rate substantially faster than the ATP turnover rate, dependent on myosin head-tail interactions. Some mutations which cause hypertrophic (HCM) or dilated (DCM) cardiomyopathies alter the SRX-DRX equilibrium, but not all mutations. The cardiac myosin inhibitor mavacamten slows nucleotide release by an equal factor for both HMM and S1, thus only indirectly influencing the occupancy time of the SRX state. These findings suggest that purified myosins undergo rapid switching between SRX and DRX states, refining our understanding of cardiomyopathy mechanisms.

肌球蛋白 ATP 酶活性的超松弛(SRX)状态对横纹肌功能至关重要,其失调与心肌病有关。目前还不清楚 SRX 状态是否容易与失调-松弛(DRX)状态发生交换,也不清楚 SRX 状态是否直接对应于折回的相互作用头基序(IHM)。利用重组的β-心肌重型纤溶酶原(HMM)和不能形成IHM的亚片段1(S1),我们发现SRX和DRX种群的转换速度大大快于ATP的周转速度,这取决于肌球蛋白头尾的相互作用。一些导致肥厚型(HCM)或扩张型(DCM)心肌病的突变会改变 SRX-DRX 的平衡,但并非所有突变都会如此。心肌肌球蛋白抑制剂马伐康坦对 HMM 和 S1 的核苷酸释放有相同的减缓作用,因此仅间接影响 SRX 状态的占据时间。这些发现表明,纯化的肌球蛋白会在 SRX 和 DRX 状态之间快速切换,从而加深了我们对心肌病机制的理解。
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来源期刊
Journal of Biological Chemistry
Journal of Biological Chemistry Biochemistry, Genetics and Molecular Biology-Biochemistry
自引率
4.20%
发文量
1233
期刊介绍: The Journal of Biological Chemistry welcomes high-quality science that seeks to elucidate the molecular and cellular basis of biological processes. Papers published in JBC can therefore fall under the umbrellas of not only biological chemistry, chemical biology, or biochemistry, but also allied disciplines such as biophysics, systems biology, RNA biology, immunology, microbiology, neurobiology, epigenetics, computational biology, ’omics, and many more. The outcome of our focus on papers that contribute novel and important mechanistic insights, rather than on a particular topic area, is that JBC is truly a melting pot for scientists across disciplines. In addition, JBC welcomes papers that describe methods that will help scientists push their biochemical inquiries forward and resources that will be of use to the research community.
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