Search for the Structural Basis of Biomacromolecular Function and Activity

（一）.我们已经在RAP中发现了一种新的组氨酸开关，细胞使用该开关来介导受体成熟过程中低密度脂蛋白受体相关蛋白（LRP）的结合/释放（Mol. Cell，2006，22（3）：423-30）。组氨酸开关踪迹的发现为螯合受体开辟了一条新途径。我们在研究过程中产生的突变体在治疗与LRP受体相关的疾病中具有潜在的治疗应用。在本项目的过程中，我们还完成了RAP蛋白的结构测定。RAP是一种蛋白伴侣，在细胞内低密度脂蛋白受体的折叠/运输中起重要作用。由于RAP结构的性质，确定RAP的3D结构非常困难。我们的团队已经成功地确定了RAP的三维结构，使用溶液NMR和小角中子散射（SANS）的组合。RAP的3D结构提供了对蛋白质多功能性的结构基础的第一次洞察。该结果已发表在Prot。科学，2007，16（8）：1628-40.我们将继续研究LRP受体在Wnt/β-catenin信号通路中的作用。我们已经成功地克隆和表达可溶性胞外结构域的LRP 5和LRP 6（LRP 5/6）受体在大规模使用的昆虫细胞。目前，我们正在研究一种实用的方法来大规模纯化受体。我必须指出，我们在这方面的研究进度，取决于分配给我的科的资源，并受其限制。（二）、我们已经完成了蛋白质L11在自由，在L11-RNA二元和L11-RNA-thiostrepton三元复合物的结构和动力学研究，并揭示了结构和动力学基础L11门控参与蛋白质合成中的延伸的各种组件的运动。这一结果对于理解蛋白质合成中的延伸/易位反应的机制具有重要意义。这项工作已发表在J. Mol. 2007，367（4），1007-1022。（三）、我们已经完成了3 P计划的开发。3 P程序使用来自单个排列张量的残余偶极耦合来确定蛋白质的骨架结构。一个J. Magn. Res.的文章，提出了严格的理论处理和3 P方法的程序的详细描述是在印刷。（四）、3UTR RNA（100 nt）结构的测定正在顺利进行中。目前，我们已经用各种同位素标记和突变方案制备了几个NMR样品;我们已经在国家阿贡实验室收集了几个RNA构建体的高质量X射线小角和广角散射数据集;我们正在开发计算协议，该协议需要在散射数据的约束下细化RNA结构;我们正在记录溶液核磁共振谱的阵列，这是阐明溶液中RNA分子结构细节所必需的。我们已经开发了3UTR RNA的初始结构模型。

(1). We have discovery a novel histidine switch in RAP that cell uses to mediate the binding/release of the low-density lipoprotein receptor related protein (LRP) in the receptor maturation process (Mol. Cell, 2006, 22(3):423-30). The discovery the histidine switch trail blazes a new way to sequester receptors. The mutants that we have made during the course of the study have potential therapeutic applications in treatment of diseases involved with the LRP receptors. During the course of this project, we have also completed the determination of the structure of protein RAP. RAP is a protein chaperone and plays an important role in folding/trafficking of the low-density lipoprotein receptors in cells. Due to the nature of the RAP structure, it has been extremely difficult to determine the 3D structure of RAP. Our group has successfully determined the 3D structure of RAP using a combination of the solution NMR and the Small Angle Neutron Scattering (SANS). The 3D structure of RAP provides the first insight into the structural basis of versatility of the protein. This result has been published in Prot. Sci., 2007, 16(8):1628-40. We will continue our studies of the roles of the LRP receptors in the Wnt/beta-catenin signaling pathway. We have successfully cloned and expressed the soluble extracellular domains of the LRP5 and LRP6 (LRP5/6) receptors on a large scale using the insect cells. At the present time, we are working on a practical procedure to purify the receptors on a large scale. I should point out that the pace of our research in this area depends on and is limited by the resource that was allocated to my section. (2). We have completed the structural and dynamics studies of protein L11 in free, in the L11-RNA binary and the L11-RNA-thiostrepton ternary complexes, and revealed the structural and dynamics basis for L11 to gate the movements of various components involved in the elongation in protein synthesis. This result is of fundamental importance in understanding the mechanism of the elongation/translocation reaction in the protein synthesis. This work has been published in J. Mol. Biol. 2007, 367(4), 1007-1022. (3). We have completed the development of the 3P program. The 3P program uses the residual dipolar couplings from a single alignment tensor to determine the backbone structure of a protein. A J. Magn. Res. article that presents a detailed description of rigorous theoretical treatment and the programs of the 3P method is in press. (4). The determination of the structure of a 3UTR RNA (100 nt) is well underway. At the present time, we have made several NMR samples with various isotope-labeling and mutation schemes; we have collected high quality X-ray small and wide angle scattering data sets of several RNA constructs at the National Argonne Laboratory; we are developing the computational protocol that is required to refine RNA structures with restraints of scattering data; we are recoding an arrays of solution NMR spectra that are required to elucidate structural details of RNA molecules in solution.; we have developed the initial structural model of the 3UTR RNA.