CRYSTAL STRUCTURE OF SQS1 AND CATCH S1 AND TROPOMYOSIN

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。肌肉收缩需要来自粗纤维的肌凝蛋白头与肌动蛋白的循环相互作用，肌动蛋白是细纤维的主要成分。我们试图通过获得不同收缩状态下的分子快照，在原子细节上可视化肌凝蛋白运动是如何工作的。在过去的几年里，我们已经确定了扇贝肌凝蛋白头部在各种弱肌动蛋白结合状态下的原子结构，以及一段使分子二聚化的肌凝蛋白尾部。肌凝蛋白马达由钙离子打开和关闭，钙离子与脊椎动物骨骼肌细丝上的肌钙蛋白/原肌凝蛋白结合。对这些结构进行完整的原子描述是为了理解运动活动是如何被控制的。我们现在已经确定了近80%横纹肌原肌球蛋白分子的原子结构。为了实现我们的目标，必须完全了解肌肉组成蛋白之间的相互作用。我们的长期目标是获得适合x射线分析的这些蛋白质的复合物。目前，我们手头上有肌凝蛋白和原肌凝蛋白的特定异构体晶体，其不寻常的性质特别适合于了解肌动蛋白的结合。我们最近结晶，收集了中分辨率x射线数据，并部分细化了鱿鱼肌凝蛋白头部的结构，这是第一次显示出肌肉肌凝蛋白的严格的强肌动蛋白结合构象。我们还获得了非肌肉原肌凝蛋白异构体的晶体，它与肌动蛋白的结合比传统的原肌凝蛋白紧密得多。从这些晶体和相关晶体中获得高分辨率同步加速器数据将是理解这些分子功能所必需的特征的关键一步。许多肌肉疾病是由于肌凝蛋白运动、肌动蛋白成分和控制机制的缺陷造成的。我们的研究旨在为基于结构的药物设计提供信息。

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. Muscle contraction requires the cyclic interactions of myosin heads from the thick filaments with actin, the major component of the thin filament. We seek to visualize, in atomic detail, how the myosin motor works by obtaining ¿¿¿snapshots¿¿¿ of the molecule in different states of contraction. Over the past few years, we have determined the atomic structures of the scallop myosin head in a variety of ¿¿¿weak actin-binding¿¿¿ states, as well as a piece of the myosin tail that dimerizes the molecule. The myosin motor is switched ¿¿¿on¿¿¿ and ¿¿¿off¿¿¿ by calcium ions which bind to troponin/tropomyosin on the thin filament in vertebrate skeletal muscles. A complete atomic description of these structures is sought to understand how motor activity is controlled. We have now determined the atomic structure of nearly 80% of the striated muscle tropomyosin molecule. To accomplish our goals, a complete understanding of the interactions between the component proteins of muscle must be obtained. Our long term aim is to obtain complexes of these proteins that are suitable for X-ray analysis. Currently, we have in hand crystals of specific isoforms of myosin and tropomyosin whose unusual properties are especially suited for understanding actin binding. We have recently crystallized, collected medium resolution X-ray data, and partially refined the structure of the squid myosin head, which for the first time has shown the rigor-like strong actin-binding conformation of a muscle myosin. We have also obtained crystals of a non-muscle tropomyosin isoform that binds actin much tighter than conventional tropomyosins. Obtaining high resolution synchrotron data from these and related crystals will be a critical step towards understanding the features of these molecules necessary for their functions. Many muscle diseases are due to defects in the myosin motor, the actin component, and in the control machinery. Our studies aim to establish information for structure-based drug design.