A model of stereocilia adaptation based on single molecule mechanical studies of myosin I
A model of stereocilia adaptation based on single molecule mechanical studies of myosin I
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DOI：
10.1098/rstb.2004.1559
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发表时间：
2004-12-29
影响因子：
6.3
通讯作者：
Molloy, JE
中科院分区：
文献类型：
--
作者：
Batters, C;Wallace, MI;Molloy, JE
我们使用基于光学镊子的仪器对非常规肌球蛋白Myo1b和Myo1c进行单分子力学实验。这些肌凝蛋白的单头性质和缓慢的atp酶动力学使它们成为详细研究肌动蛋白产生力的分子机制的理想选择。Myo1c表现出几个使用快速骨骼肌肌球蛋白II未观察到的特征。(i)工作行程分为两个不同的阶段，产生最初的3nm，然后再产生1.5 nm的运动。（ii）观察到两种类型的结合相互作用：短期的不依赖于atp的结合事件，不产生运动；长期的依赖于atp的事件，产生完整的工作卒中。两种相互作用的刚度相似。在一种新型的实验中……使用反馈将控制位移应用于单个肌动蛋白-肌球蛋白交叉桥，我们发现在肌动蛋白-肌球蛋白交叉桥的附着过程中，力会发生突然变化，这一结果与单个肌肉纤维的经典“T-2”行为一致。考虑到这些肌凝蛋白可能表现出经典的T-2行为。我们提出了一个新的模型来解释内耳毛细胞的感觉适应的缓慢阶段。
We have used an optical tweezers-based apparatus to perform single molecule mechanical experiments using the unconventional myosins, Myo1b and Myo1c. The single-headed nature and slow ATPase kinetics of these myosins make them ideal for detailed studies of the molecular mechanism of force generation by, acto-myosin. Myo1c exhibits several features that have not been seen using fast skeletal muscle myosin II. (i) The working stroke occurs in two, distinct phases, producing an initial 3 nm and then a further 1.5 nm of movement. (ii) Two types of binding interaction were observed: short-lived ATP-independent binding events that produced no movement and longer-lived, ATP-dependent events that produced a full working stroke. The stiffness of both types of interaction was similar. (iii) In a new type of experiment.. using feedback to apply controlled displacements to a single acto-myosin cross-bridge, we found abrupt changes in force during attachment of the acto-Myo1b cross-bridge, a result that is consistent with the classical 'T-2' behaviour of single muscle fibres. Given that these myosins might exhibit the classical T-2 behaviour. we propose a new model to explain the slow phase of sensory adaptation of the hair cells of the inner ear.