Visualizing Actomyosin Transients by Data Merging

说明(申请人提供)：肌球蛋白与肌动蛋白结合，将ATP中的化学自由能转化为肌动蛋白的形式，对抗相反的作用力。来自生化动力学数据的推论表明，肌动球蛋白相互作用由一系列状态组成，在这些状态下，ATP降解的每个中间体对应于一种独特的肌动球蛋白构象。肌球蛋白球状头部或亚片段1(S1)的晶体结构显示，一个由几乎完整的N端催化结构域和C端杠杆臂结构域组成的关节分子，由于中间肽中的局部变形而改变了它们的相对位置。该系统的工作原理是放大催化结构域活性部位的小结构变化，在那里ATP被水解为大的杠杆-臂结构域运动。阐明活性部位结构变化为杠杆-臂运动的传播和放大机制是通过构建显式模型来实现的主要目的。该模型涉及能量转导中的单个残基参与者，从而可以现实地分析特定残基修饰或突变的影响。在目标1中，来自战略定位的外在探针和内在的ATP敏感色氨酸的光谱检测转导过程中的肌球蛋白构象。在目标2中，生化和分子生物学方法探索了肌动球蛋白相互作用中结构表面环的作用。目标3是利用能量传导模型，结合AIMS 1和AIMS 2数据的结构含义，从蛋白质数据库中挖掘出的晶体结构，建立代表收缩周期中骨骼肌动球蛋白构象的原子结构。该模型同时满足了来自结晶学、光谱学和生物化学/分子生物学的多个独立的要求，以得出肌球蛋白转导中间结构的最佳解决方案。此外，随着新数据的出现，该模型将受到累积改进的影响。目标4是实现可验证的可靠例程，用于将多肽结构转换为光谱信号，这一过程的准确性对所提议的模型建立至关重要。结构到光谱的转换例程对于生物物理学中的结构传感光学光谱学具有更广泛的意义。

DESCRIPTION (provided by applicant): The motor protein myosin in association with actin transduces chemical free energy in ATP into work in the form of actin translation against an opposing force. Inferences from biochemical kinetic data suggest the actomyosin interaction consists of a series of states for which each intermediate in the degradation of ATP corresponds to a unique actomyosin conformation. Crystal structures of the myosin globular head or subfragment 1 (S1) representing the ATP hydrolysis intermediates show an articulated molecule made from nearly intact N-terminal catalytic and C-terminal lever-arm domains that change their relative position due to localized deformations in the intervening peptide. The system works by amplifying small structure changes in the catalytic domain active site where ATP is hydrolyzed into the large lever-arm domain movement. Elucidating the mechanism for propagation and amplification of the active site structure changes into the lever-arm movement is the principal aim of the proposal to be accomplished by construction of an explicit model. The model involves individual residue participants in energy transduction such that the effect of a specific residue modification or mutation may be realistically analyzed. In Aim 1, spectroscopy from strategically located extrinsic probes and an intrinsic ATP-sensitive tryptophan detect myosin conformation during transduction. In Aim 2, biochemical and molecular biological approaches probe the role of a structured surface loop in the actomyosin interaction. Aim 3 is to build the atomic structures representing skeletal actomyosin conformation during the contraction cycle from crystallographic structures mined from the protein database combined with structural implications from Aims 1 and 2 data using the energy transduction model. The model satisfies simultaneously, multiple independent requirements from crystallography, spectroscopy, and biochemistry/molecular-biology to arrive at a best solution for the myosin transduction intermediate structure. Additionally, the model is subject to cumulative improvement as new data becomes available. Aim 4 is to implement verifiably reliable routines for translating peptide structure to a spectroscopic signal, a process whose accuracy is critical to the proposed model building. The structure to spectrum translation routines have broader implications for structure sensing optical spectroscopy in biophysics.