Group-Theoretic Methods in Protein Structure Determina-n

描述（由申请人提供）：通知：NOT-OD-09-058，NIH宣布恢复法案基金可用于竞争性申请摘要声明“蛋白质结构测定中的群论方法”本补充申请的重点是分析柔性蛋白质构象集合的统计数据。也就是说，而最初的资助重点是从各种实验模式中确定蛋白质结构的新算法，这个补充申请的目标是量化结构数据中所代表的构象的可变性。其中一个最明显的例子是在NMR中，其中通常报告构象的集合而不是单个结构。在这九个月的高度集中的努力中，除了最初的三个具体目标之外，还将解决以下具体目标：具体目标4：有效生成柔性环构象的包络统计。在这个特定的目标，新的方法从机器人机械手运动学领域的卷积和协方差传播的概念的基础上的刚体运动的组将被用来生成合奏统计的候选环路构象没有明确采样构象空间。通过规避与传统采样技术相关的指数价格，我们预计在分析蛋白质环构象的方式上产生质的差异，而不仅仅是在特定计算中的定量差异。作为一个具体的测试案例，我们将应用这种方法来确定人类Ube 2g 2的结构。具体目标5：评价二级结构组装中环的偏置效应。在这个特定的目标，我们将研究环路长度/组成和所产生的二级结构相互作用的特殊几何特征之间的相关性。我们将开始考虑螺旋-环-螺旋基序中的螺旋-螺旋相互作用以及螺旋相互作用参数与定义环的参数之间的关系。换句话说，我们将检查几何特性，如交叉角以及螺旋线沿沿着螺旋线长度相互接触的位置，这些都取决于环路参数。这是一个纯粹的计算机目标，它将涉及从蛋白质数据库中挖掘数据。具体目标6：表征三级包体。我们将评估以下假设：蛋白质三级结构并不总是以单一构象存在，并且“三级系综”成员的计数将比假设单一构象的模型更好地匹配实验数据。我们将测试这一假设验证三级合奏对NMR残留偶极耦合。特别是，我们建议利用脑膜炎奈瑟氏球菌血红素加氧酶（nmHO）作为我们的能力，以产生三级合奏，保持，甚至提高，如RDC的NMR数据的协议的测试情况。由于原始赠款目前处于无成本延长阶段，几乎所有的资金都已用完，这种竞争性的更新将为PI/co-PI工资，博士后和两名学生提供持续资助的途径，为期九个月。这一数额连同实验室用品的拟议预算构成拟议的请求。 公共卫生相关性：这个补充应用程序的重点是分析柔性蛋白质构象系综的统计。也就是说，而最初的资助重点是从各种实验模式中确定蛋白质结构的新算法，这个补充申请的目标是量化结构数据中所代表的构象的可变性。

DESCRIPTION (provided by applicant): Notice: NOT-OD-09-058, NIH Announces the Availability of Recovery Act Funds for Competitive Applications SUMMARY STATEMENT "Group Theoretic Methods in Protein Structure Determination" The emphasis of this supplemental application is to analyze the statistics of ensembles of conformations of flexible proteins. That is, whereas the original grant focuses on new algorithms for determining protein structures from a variety of experimental modalities, the goal of this supplemental application is to quantify the variability of conformations represented in structural data. One of the most obvious examples of this is in NMR, where ensembles of conformations are often reported rather than an individual structure. The following specific aims to be addressed in this highly focused nine-month effort add to the original three specific aims: Specific Aim 4: Efficient Generation of Ensemble Statistics of Flexible Loop Conformations. In this specific aim, new methods from the field of robotic manipulator kinematics based on the concept of convolution and covariance propagation on the group of rigid-body motions will be used to generate ensemble statistics of candidate loop conformations without explicitly sampling conformational space. By circumventing the exponential price associated with traditional sampling techniques, we anticipate making a qualitative difference in the way protein-loop conformations are analyzed, not just a quantitative difference in particular computations. As a concrete test case, we will apply this methodology to the structure determination of human Ube2g2. Specific Aim 5: Evaluation of the Biasing Effects of Loops in the Assembly of Secondary Structures. In this specific aim we will study the correlation between loop length/composition and the special geometric characteristics of the resulting secondary structure interactions. We will begin by considering the helix-helix interaction in the helix-loop-helix motif and the relationship between helix interaction parameters and the parameters defining the loop. In other words, we will examine geometric characteristics such as crossing angle and where along the helix lengths the helices contact each other that depends on loop parameters. This is a purely in- silico objective, which will involve mining data from the Protein Data Bank. Specific Aim 6: Characterizing the Tertiary Ensemble. We will evaluate the following hypothesis: Protein tertiary structures do not always exist as single conformations, and enumeration of members of the 'tertiary ensemble' will better match experimental data than models in which a single conformation is assumed. We will test this hypothesis by validating tertiary ensembles against NMR residual dipolar couplings. In particular, we propose to utilize Neisseria meningitidis Heme Oxygenase (nmHO) as a test case of our ability to generate tertiary ensembles which maintain, or even improve, agreement with NMR data such as RDCs. Since the original grant is currently in no-cost extension, and almost all of the funds have been spent, this competitive renewal will provide an avenue for the continued funding of PI/co-PI salaries, a postdoc, and two students for a nine-month period. This, together with the proposed budget for laboratory supplies, constitutes the proposed request. PUBLIC HEALTH RELEVANCE: The emphasis of this supplemental application is to analyze the statistics of ensembles of conformations of flexible proteins. That is, whereas the original grant focuses on new algorithms for determining protein structures from a variety of experimental modalities, the goal of this supplemental application is to quantify the variability of conformations represented in structural data.