HIV-1 Capsid Protein/Cyclophilin-A Complex : A Structural Study

描述（由申请人提供）：人类免疫缺陷病毒1型（HIV-1）在其生命周期中利用大量宿主细胞蛋白。其中比较突出的蛋白质是人亲环蛋白A (CypA)，它被病毒用于最佳的感染性和病毒复制。CypA的一些假定功能已经被假设，但我们对其在HIV-1生命周期中的确切作用的理解仍然是初级的。为了响应PA-06-388的公告，在当前的R21/R33应用中，提出了一种结合溶液核磁共振和生物物理模拟的研究方法，以确定与亲环蛋白a结合的HIV-1衣壳蛋白（CA）的详细三维结构。野生型全长CA与CypA结合的结构研究已经挫败了晶体学和核磁共振光谱的尝试。因此，在本研究中，我们将使用双突变体CA来研究CypA/CA复合物，该突变体作为单体存在于溶液中，并保留野生型CA的所有关键特性，包括组装活性。利用3D/ 4d核磁共振光谱，剩余偶极耦合测量和生物物理模拟，我们将确定双突变体CA的详细溶液结构，以及它与人类CypA的配合物。了解CypA/CA复合物的详细结构将为我们进一步了解CypA在病毒生命周期中的确切作用提供结构生物学基础。这种结构也可能有助于开发具有治疗潜力的CypA-CA相互作用的新抑制剂。公共卫生相关性：本研究旨在使用联合溶液核磁共振和生物物理模拟方法确定与HIV-1病毒突变衣壳蛋白结合的人亲环蛋白A的详细三维结构。

DESCRIPTION (provided by applicant): The human immunodeficiency virus type 1 (HIV-1) exploits a large number of host cellular proteins in its life cycle. Among the more prominent proteins is the human cyclophilin A (CypA) which is utilized by the virus for optimal infectivity and viral replication. A number of putative functions have been postulated for CypA but our understanding of its precise role within HIV-1 life cycle is still rudimentary. In response to the PA-06-388 announcement, a combined solution NMR and biophysical simulation investigation is proposed in the current R21/R33 application to determine the detailed three dimensional structure of the HIV-1 capsid protein (CA) bound to cyclophilin A. Because of its inherent flexibility, tendency to oligomerize, and its monomer-dimer equilibrium in solution, a structural study of the wild type full-length CA bound to CypA has frustrated attempts by crystallography and NMR spectroscopy. Thus in this investigation we will study the CypA/CA complex using a double mutant CA that exists as a monomer in solution, and retains all the critical properties of the wild type CA including assembly activity. Utilizing 3D/4D-NMR spectroscopy, residual dipolar coupling measurements and biophysical simulations, we will determine the detailed solution structure of the double mutant CA, and of its complex with human CypA. A knowledge of the detailed structure of the CypA/CA complex will provide a structural biology basis in enhancing our understanding of the precise role of CypA within the life cycle of the virus. Such a structure is also likely to contribute to the development of new inhibitors of CypA-CA interaction with therapeutic potential. PUBLIC HEALTH RELEVANCE: This investigation is aimed at the determination of the detailed three dimensional structure of the human Cyclophilin A bound to a mutant capsid protein of HIV-1 virus using a combined solution NMR and biophysical simulation approach.