MODELLING THE INTERFACE BETWEEN ACTIN AND MYOSIN ON ACTIVE MUSCLE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 以前的研究人员根据分离蛋白质的结晶学和电子显微镜数据提出了肌球蛋白头部与肌动蛋白对接的高分辨率模型(Mendelson和Morris，1997 PNAS 94：8533；Holmes等人)。2003年自然425：423)。另一个小组还声称，力产生的第一步与肌球蛋白-肌动蛋白界面的重新排列有关，随后是杠杆臂倾斜，而且它是温度相关的(Ferenczi等人。2005年结构13：131)。这项工作的目的是收集肌肉的小角X射线散射(SAXS)数据，用于在体内检查Acto-Myosin对接模型的预测，以及是否存在依赖于温度的肌球蛋白-肌动蛋白界面重排。为此，模式中最敏感的反射是2.73 nm的经向反射，这是由于肌动蛋白单体沿肌动蛋白细丝的规则重复而产生的，这改变了肌球蛋白与肌动蛋白连接时的强度。初步模拟表明，杆臂倾斜度对反射强度影响不大，但对肌动蛋白的相对轴向位置和肌球蛋白的催化结构域高度敏感。在不同温度(4~17℃)至0.5 nm-1的倒置空间中，从静息和等长收缩过程中的肌肉获取2D模式，以收集基于肌动蛋白的2.73 nm经向反射以及5.9 nm和5.1 nm层线，也受肌球蛋白与肌动蛋白附着的影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Previous workers have proposed high resolution models for the docking of the myosin heads on actin on the basis of combined crystallographic and electron microscopy data from isolated proteins (Mendelson and Morris, 1997 PNAS 94:8533; Holmes et al. 2003 Nature 425:423). Another group also claims that the first step in the force generation is associated with a rearrangement of the myosin-actin interface, followed by the lever arm tilt, and that it is temperature-dependent (Ferenczi et al. 2005 Structure 13:131). The goal of this work is to collect small angle X-ray scattering (SAXS) data from muscle that may be used to check in vivo the prediction of the models for the acto-myosin docking and whether there is a temperature-dependent rearrangement of the myosin-actin interface. For this purpose, the most sensitive reflection in the pattern is the 2.73nm meridional reflection arising from the regular repeat of the actin monomers along the actin filament, which changes its intensity upon myosin attachment to actin. Preliminary modelling has shown that the reflection intensity is little influenced by the lever arm tilt but it is highly sensitive to the relative axial position of actin and catalytic domain of myosin. 2D patterns will be taken from muscle at rest and during isometric contraction at different temperatures (4 to 17¿C) up to 0.5 nm-1 in reciprocal space, in order to collect the actin-based 2.73nm meridional reflection and the 5.9nm and 5.1nm layer lines, also influenced by myosin attachment to actin.