X-RAY CRYSTALLOGRAPHIC ANALYSIS OF MUSCLE PROTEINS

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 为子项目列出的总成本可能 表示子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 我们收集了扇贝肌球蛋白头部和尾部的晶体数据。根据我们最近对扇贝肌球蛋白头（S1）肌动蛋白分离、内部解偶联状态的高分辨率晶体结构的研究（Himmel等人，筹备中;在我们的CHESS Progress Report of 2001中报道的），我们现在已经获得了在前动力冲程或引发构象中的S1的2.6 A分辨率结构（Gourinath，et al.，正在筹备中）。这两种结构，这在子域相互作用有很大的不同，比较将提供关键信息的灵活性的联系在不同状态的收缩周期。到目前为止，还没有关于肌球蛋白尾部任何部分的详细结构的报道。使用收集到的数据，以2.6A的分辨率在国际象棋，我们正在确定一个50残基长的扇贝肌球蛋白尾部，位于肌球蛋白头附近的部分的结构。尾部的该区域对于肌球蛋白分子的调节特性是关键的（Li等人，正在筹备中）。基于过去几年在CHESS收集的数据，我们还发表了关于原肌球蛋白和纤维蛋白原关键片段的晶体结构的报告。根据我们对原肌球蛋白的N-末端片段的工作（Brown等人，2001），我们现在已经建立了31个残基的横纹肌原肌球蛋白的C-末端片段的结构，它显示出不寻常的张开构象。这些结果揭示了肌钙蛋白T的特异性识别位点，并阐明了横纹肌独特调节机制的物理基础（Li et al.，PNAS，in press）.在我们努力了解血液凝固的分子基础，我们也追求纤维蛋白原的晶体结构。我们先前报道了牛纤维蛋白原的285 kDa骨架的4A结构（Brown等人，2000），并且现在已经实现了分子的中心结构域的1.4 A分辨率结构（Madrazo等人，2001年）。这种结构具有显著的二聚体界面，这在以前是不可见的。总之，这些结果提高了我们对纤维蛋白原凝块中分子组装的理解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have collected crystal data from both the head and tail regions of scallop myosin. Following our recent study on the high-resolution crystal structure of the actin-detached, internally-uncoupled state of the scallop myosin head (S1) (Himmel, et al., in preparation; reported in our CHESS Progress Report of 2001), we have now obtained a 2.6A resolution structure of S1 in the pre-power stroke or primed conformation (Gourinath, et al., in preparation). Comparison of these two structures, which differ greatly in subdomain interactions, will provide key information on the flexibility of linkages in different states of the contractile cycle. Until now, there has not been a detailed structure reported for any part of the tail of myosin. Using data collected to 2.6A resolution at CHESS, we are determining the structure of a 50-residue-long segment of the scallop myosin tail, located adjacent to the myosin head. This region of the tail is critical for the regulatory properties of the myosin molecule (Li et al., in preparation). Based on data collected at CHESS during the past few years, we have also published reports on crystal structures of key fragments of tropomyosin and fibrinogen. Following our work on an N-terminal fragment of tropomyosin (Brown et al., 2001), we have now established the structure of a 31-residue C-terminal segment of striated-muscle tropomyosin, which shows an unusual splayed conformation. These results reveal a specific recognition site for troponin T and clarify the physical basis for the unique regulatory mechanism of striated muscles (Li et al., PNAS, in press). In our efforts to understand the molecular basis of blood clotting, we have also pursued crystal structures of fibrinogen. We previously reported the 4A structure of the 285 kDa backbone of bovine fibrinogen (Brown et al., 2000), and have now achieved a 1.4A resolution structure of the central domain of the molecule (Madrazo et al., 2001). This structure has a remarkable dimeric interface, which could not previously be visualized. Taken together, these results have improved our understanding of the assembly of the molecule into the fibrinogen clot.