Crystal Structures of CXCR4 complexed to CXCL12

描述（由申请人提供）：CXCR4是一种g蛋白偶联受体，由唯一的生理激动剂，趋化因子CXCL12激活，其功能是在胚胎发育期间和成人应激反应中引起细胞向适当的解剖位置迁移。CXCR4还参与多种癌症的生长和/或转移，是HIV-1的共同受体，突变的CXCR4会导致一种称为WHIM综合征的免疫抑制状况。疱疹病毒-8释放的趋化因子v-MIP-II是CXCR4的拮抗剂。CXCL12和vCCL2属于趋化因子家族的不同亚家族，根据其序列和结构的定义，它们有望激活其亚家族中的受体。该提案旨在确定CXCR4与(a)作为拮抗剂的突变CXCL12P2G和(b)在溶液中主要为单体的另一突变（H25R）背景下的CXCL12P2G复合物结构的三维结构。已知糖胺聚糖与大多数趋化因子相互作用，促进二聚体和寡聚的形成。在存在和不存在肝素双糖的情况下进行结晶(已知在两个位置结合CXCL12（由PI实验室的x射线晶体学确定）并促进二聚化也将进行，以验证糖胺聚糖向其受体呈现趋化因子的假设。这些结构将与CXCR4-AMD3100（一种小分子拮抗剂）复合物进行比较，该复合物已由合作者（Ray Steven博士，Scripps研究所）结晶，其高分辨率结构正在进行中。CXCR4的结构工作将为未来涉及内源性和HIV-1蛋白结合CXCR4并具有医学相关性的工作奠定基础。

DESCRIPTION (provided by applicant): CXCR4 is a G-protein coupled receptor is activated by a sole physiological agonist, the chemokine CXCL12 and functions to cause the migration of cells to the appropriate anatomical location during embryonic development and in response to stress in adults. CXCR4 is also involved in growth and/or metastasis of a number of cancers, is a co-receptor for HIV-1, and mutant CXCR4 causes an immunosuppressive condition known as WHIM syndrome. A chemokine released by herpesvirus-8, v-MIP-II, is an antagonist of CXCR4. CXCL12 and vCCL2 belong to different subfamilies of the chemokine family as defined by their sequence and structure, and would be expected to expected to activate receptors within their subfamily. This proposal aims to determine the three-dimensional structures of the structures of CXCR4 complexed to (a) mutated CXCL12P2G that functions as an antagonist and (b) CXCL12P2G in the context of another mutation (H25R), which is predominantly a monomer in solution. Glycosaminoglycans are known to interact with most chemokines and promote the formation of dimers and oligomerization. Crystallization in the presence and absence of a heparin disaccharide known to bind CXCL12 at two locations (determined by X-ray crystallography in the PI's lab) and to promote dimerization will also be performed to test the hypothesis that glycosaminoglycans present chemokines to their receptors. These structures will be compared to each other and the CXCR4-AMD3100 (a small molecule antagonist) complex, a complex which has been crystallized by the collaborator (Dr. Ray Steven's, Scripps Institute) and its high resolution structure is in progress. Structural work with CXCR4 will lay the foundation for future work involving endogenous and HIV-1 proteins that bind CXCR4 and have medical relevance. PUBLIC HEALTH RELEVANCE: The chemokine receptor CXCR4 is a G-protein coupled receptor involved in HIV-1 entry, the metastasis and growth of several cancers and, when mutated at the C-terminus, responsible for the immunosuppressive disorder known as WHIM syndrome. It is also the target of the drug, Plexifor, for CD34+ peripheral cell mobilization used for multiple myeloma and non-Hodgkin's lymphoma. This proposal seeks to determine the three-dimensional structure of CXCL12 complexed to CXCR4.