Myofibrillar Structure of Striated Muscle

令人兴奋的最新进展有望从电机的时间分辨结构分析中获得继续的启示 肌肉中的分子，以阐明单独的运动动作以及它们在 整个肌肉。巨水虫甘油昆虫飞行肌肉的高结晶级 Lethocerus给出了来自每种生理状态的独特的X射线衍射(X光)，并允许无与伦比的 肌球蛋白交叉桥的薄层电子显微镜(EM)图像。将图像载体与 原生X射线图样测量和验证薄片EM的保真度。新的同步加速器X射线光束线 探测器允许使用新的方法。我们将把时间切片同步加速器X射线衍射与EM 3- 从速冻纤维进行三维重建(3-D)，以将机械数据与结构数据相结合 肌球蛋白力量中风的毫秒级快照。有源交叉桥分集的三维分析 状态是基于3-D EM层析成像的，它可以呈现非平均结构，但也允许部分 或全平均，以及3D对应分析，以分类和计算不同的十字桥形状。 在主动态、Rigor态和AMPPNP态下IFM高力跨桥的TI荷载引起的变形将是 采用阶梯/坡道长度变化实现机械同步，并用X射线、三维电子显微镜研究了低温和化学过程。 固定纤维，以及肌球蛋白和肌动蛋白晶体结构模型的拟合。部队生成计划将是 以这些配件为原型。一种低力(PowerStroke前)的有源电桥，在高[Ca~+J]时受到青睐 冷却、高[PI]和PI类似物(BDM、钒酸盐、AlF4~、BeFx)将与高力桥梁进行比较 使用X射线、3D-EM和原子模型的拟合(速冻IFM纤维的FT-X-射线低温衍射将 被开发为在记录高分辨率曝光的同时防止高通量辐射损害，以及 冻结捕捉稳定的、不断演变的、甚至可能是动态的状态。4肌球蛋白在交叉桥的S1-S2连接 IFM的起源将通过粗丝的低盐晶格膨胀和高盐松动来探索 我的脊梁。松弛IFM中的粗丝和A带结构将从我们的 在2？、20？和40？(活体正常飞行温度)下的X射线数据，使用我们的辅助EM研究 生成模型几何图形。

Exciting recent progress promises continued revelations from time-resolved structural analysis of motor molecules in muscle, to clarify individualmotor actions as well as their integrated ensemble performance in whole muscles. High paracrystalline order of glycerinated insect flight muscle (IFM)from giant waterbug Lethocerus gives distinctive X-ray diffraction (X-ray) from each physiological state, and allows unexcelled thin-section electron microscope (EM) images of myosin crossbridges. Comparing image Fouriers with native X-ray patterns measures and validates fidelity of thin-section EM. New synchrotron X-ray beamlines and detectors allow new methods. We will coordinate time-sliced synchrotron X-ray diffraction with EM 3- D reconstructions (3-Ds) from quick-frozen fibers to integrate mechanical with structural data for millisecond-timed snapshots of the myosin power stroke. 3-D analysis of crossbridge diversity in active states is based on 3-D EM tomography, which can present non-averages structures, but also allows partial or full averaging, as well as 3D correspondence analysis to classify and count different crossbridge shapes. ti Load-induced distortions of IFM high-force crossbridges in active, rigor and AMPPNP states will be mechanically synchronized by step/ramp length changes and studied by X-ray, 3D EM of cryo- and chem- fixed fibers, and fitting of crystal-structure models of myosin and actin. Force generation schemes will be modeled from these fittings. A Low-force (pre-powerstroke) active bridges, to be favored at high [Ca~+J by cooling, high [Pi],and Pi analogs (BDM, vanadate, A1F4~, BeFx), will be compared with high-force bridges using X-ray, 3D-EM and fitting of atomic models, (ft X-ray cryodiffraction of quick-frozen IFM fibers will be developed to protect against high-flux radiation damage while recording high resolution exposures, and to freeze-capture stable, evolving and maybe dynamic states. 4 Myosin's S1-S2 junction at the crossbridge origin in IFM will be probed by low-salt lattice swelling and high-salt loosening of the thick filament backbone. A Thick filament and A-band structure in relaxed IFM will be collaboratively modeled from our X-ray data at 2¿, 20¿ and 40¿ (normal flight temperature in vivo), using our supporting EM studies to generate model geometry.