由冷电子显微镜揭示的原生心脏薄丝中的热素结构动力学
Cristina M Risi1, Betty Belknap1, Jennifer Atherton1
1Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23507, USA.
Journal of molecular biology
|February 22, 2024
概括
心脏中素 (cTF) 结构揭示了影响肌肉收缩的多种形状. 心脏肌结合蛋白C (cMyBP-C) 的结合完全激活了cTF,即使没有,也解释了跨桥相互作用.
科学领域:
- 分子和结构生物学 分子和结构生物学
- 心血管生理学心血管生理学
- 生物化学 生物化学
背景情况:
- 心肌收缩依赖于动氨酸-薄丝 (TF) 和肌酸-厚丝丝的相互作用.
- 这些相互作用是由Ca2+,交叉桥和心脏肌结合蛋白C (cMyBP-C) 调节的.
- 心脏类素 (cTF) 综合体调节收缩的精确结构机制尚不清楚.
研究的目的:
- 在不同的Ca2+条件下阐明cTF复合体的结构构造.
- 研究cMyBP-C在调节cTF结构和功能的作用.
- 为理解心肌激活和调节提供结构基础.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 对原生心脏薄纤维 (cTF) 进行检测.
- 在高和低的Ca2+水平下分析了热素 (Tn) 核心的结构变化.
- 评估了cMyBP-C C1域对cTF构成的影响.
主要成果:
- cTF热素核心采用多种依赖于Ca2+水平的形状,在两个丝链之间具有不同的结构.
- 高Ca2+导致部分或完全激活状态,完全激活需要完整的TnI C末端解离.
- cMyBP-C C1域诱导一个完全激活的cTF构造,独立于Ca2+.
结论:
- 结构洞察力揭示了肌蛋白在完全激活cTFs中的作用,并解释了TnC对Ca2+的增强亲和力与活跃的交叉桥梁.
- 热素子单元与热氨酸之间的合对调节动氨酸相互作用至关重要.
- 这些发现澄清了依赖的心肌收缩调节的分子基础.
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