Superspace Refinement of Protein Crystals

大分子晶体学家通过对这些分子晶体的x射线衍射分析来确定每个原子在三维空间中的位置，从而描述大分子的整个结构，从而将生命所需的大分子的细节可视化。然而，有时晶体不能以允许精确的x射线衍射和分析的方式形成。处理这个问题的分析工具，当它发生时，还没有开发出来，这个研究项目的目标是提供研究这种性质的蛋白质晶体的原子结构所需的方法和计算机软件。这种方法将在计算上为结构分析增加另一个（第4）维度，允许定义分子的“超结构”。这个极具创新性的项目将打开这一领域，允许其他人完成困难但重要的多维晶体学项目。这项研究将为研究生和本科生提供培训，包括科学界代表性不足的群体的成员。该项目包括对生物科学的许多领域有益的活动，包括大分子晶体学、细胞生物学和DNA修复。该项目的重点是结构确定的非相应调节的蛋白质晶体。调制晶体的独特衍射图案包含主反射旁边的“离晶格”卫星反射。所提议的活动的智力价值是多方面的。将解决第一个不相称调制的蛋白质晶体结构，并将在大分子晶体学的方法学上取得进展。本研究的主要目的是开发新的大分子x射线晶体学软件，用于细化超空间中的不相关调制晶体，并将其应用于解决目前无法解决的几种晶体结构。所采用的方法包括蛋白质晶体生长、x射线衍射数据收集和结构测定。将使用蛋白质晶体学和软件开发的创新方法。活动将包括广泛修改晶体学软件，用于使用调制函数确定超空间中的大分子结构。模拟数据将用作测试用例。然后，将该算法应用于已充分表征的肌动蛋白、UvsY重组介质晶体等非共调晶体，以及其他许多尚未解决的调制晶体。在当前的生物/生化文献的框架内，将分析每个晶体中产生的连续结构。该项目由生物科学局分子和细胞生物科学司和生物基础设施司共同支持。

Macromolecular crystallographers visualize in extraordinary detail the large molecules needed for life, using X-ray diffraction analysis of crystals of these molecules to determine the locations of each atom in three dimensions, thereby describing the entire structure of the macromolecule. However, sometimes the crystals do not form in a way that permits accurate X-ray diffraction and analysis. The analytical tools to deal with this problem, when it happens, have not yet been developed, and the goal of this research project is to provide the methods and computer software needed to study the atomic structure of protein crystals of this nature. This method will computationally add another (4th) dimension to the structural analysis permitting "superstructures" of the molecule to be defined. This highly innovative project will open the field, permitting others to complete difficult but important multidimensional crystallography projects. This research will provide training for graduate and undergraduate students including members of groups underrepresented in science.This project includes activities that will be beneficial to many areas of the biological sciences including macromolecular crystallography, cell biology and DNA repair. The project is focused on the structure determination of incommensurately modulated protein crystals. The unique diffraction patterns from modulated crystals contain "off-lattice" satellite reflections next to the main reflections. The intellectual merits of the proposed activity are multifold. The first incommensurately modulated protein crystal structures will be solved and advances will be made to the methodology of macromolecular crystallography. The main objective of this research is to develop new macromolecular X-ray crystallographic software for the refinement of incommensurately modulated crystals in superspace and to apply them to solve several crystal structures that currently cannot be solved. The methods employed include protein crystal growth, X-ray diffraction data collection and structure determination. Innovative approaches to protein crystallography and software development will be used. Activities will include extensive modification of crystallography software for the determination of macromolecular structures in superspace using modulation functions. Simulated data will be used as a test case. Then the algorithms will be applied to well characterized incommensurately modulated crystals of profilin:actin, UvsY recombination mediator crystals and then to many other unsolved modulated crystals. The resulting continuum of structures within each crystal will be analyzed within the framework of the current biological/biochemical literature.This project is supported jointly by the Division of Molecular and Cellular Biosciences and the Division of Biological Infrastructure in the Directorate for Biological Sciences.