Laboratory of Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, St. Petersburg 194064, Russia.
Biochem Biophys Res Commun. 2011 Aug 5;411(3):496-500. doi: 10.1016/j.bbrc.2011.06.138. Epub 2011 Jun 29.
Dilated cardiomyopathy (DCM), characterized by cardiac dilatation and contractile dysfunction, is a major cause of heart failure. DCM can result from mutations in the gene encoding cardiac α-tropomyosin (TM). In order to understand how the dilated cardiomyopathy-causing Glu40Lys mutation in TM affects actomyosin interactions, thin filaments have been reconstituted in muscle ghost fibers by incorporation of labeled Cys707 of myosin subfragment-1 and Cys374 of actin with fluorescent probe 1.5-IAEDANS and α-tropomyosin (wild-type or Glu40Lys mutant). For the first time, the effect of these α-tropomyosins on the mobility and rotation of subdomain-1 of actin and the SH1 helix of myosin subfragment-1 during the ATP hydrolysis cycle have been demonstrated directly by polarized fluorimetry. The Glu40Lys mutant TM inhibited these movements at the transition from AM(∗∗)·ADP·Pi to AM state, indicating a decrease of the proportion of the strong-binding sub-states in the actomyosin population. These structural changes are likely to underlie the contractile deficit observed in human dilated cardiomyopathy.
扩张型心肌病（DCM）的特征是心脏扩张和收缩功能障碍，是心力衰竭的主要原因。DCM 可由编码心肌α-原肌球蛋白（TM）的基因突变引起。为了了解 TM 中的扩张型心肌病致病 Glu40Lys 突变如何影响肌球蛋白肌动球蛋白相互作用，通过掺入标记物肌球蛋白亚基 1 的 Cys707 和肌动蛋白的 Cys374 与荧光探针 1.5-IAEDANS 和α-原肌球蛋白（野生型或 Glu40Lys 突变型），在肌肉幽灵纤维中重新组成细纤维。首次通过偏振荧光直接证明了这些α-原肌球蛋白对肌动蛋白亚基 1 的结构域 1 的迁移和旋转以及肌球蛋白亚基 1 的 SH1 螺旋在 ATP 水解循环过程中的影响。Glu40Lys 突变 TM 在从 AM(∗∗)·ADP·Pi 到 AM 状态的转变过程中抑制了这些运动，表明肌球蛋白肌动球蛋白群体中强结合亚基的比例降低。这些结构变化可能是人类扩张型心肌病中观察到的收缩缺陷的基础。
