CCR5 & CXCR4 Antagonist & Agonist Binding Site Structure

描述（由申请人提供）： 现有抗艾滋病毒药物的耐药性、潜伏病毒库和毒性作用等问题要求开发具有不同作用方式的新型抗逆转录病毒药物。药物开发的一种有前途的方法是干扰艾滋病毒进入细胞。 HIV 进入是一个复杂的过程，需要 HIV 包膜蛋白 gp120 与细胞共受体（CCR5 或 CXCR4）结合。该提案旨在增强对 CCR5 和 CXCR4 结构的理解，包括有助于拮抗剂结合替代模式的氨基酸残基和参与激动剂激活的接触残基。需要 CCR5 才能进入的病毒分离株是人与人之间传播的 HIV 的主要传染形式。需要 CXCR4 进入的病毒株通常出现在感染的后期，被认为更具致病性，并且与 CD4 T 淋巴细胞的严重丧失以及由于严重免疫缺陷而导致机会性感染的发展相关。制药公司已将几种阻断病毒感染的 CCR5 或 CXCR4 小分子拮抗剂确定为有前景的先导药物，但它们在受体上的结合位点和阻断 HIV 的机制却知之甚少。该项目将使用拮抗剂和激动剂分子的高亲和力光活性类似物来检查 CCR5 和 CXCR4 中的相互作用位点，并将通过位点特异性诱变研究残基在交联位点的作用。我们还将通过研究针对 CCR5 拮抗剂或激动剂结合构象的单克隆抗体的相互作用位点，研究导致 HIV 结合激活或拮抗的 CCR5 构象变化。拟议的研究将有助于更好地了解 CCR5 和 CXCR4 的结构和功能，并旨在为设计更有效的药物提供有用的信息，这些药物可抑制 HIV 进入，同时最大限度地减少由于激活或阻断 CCR5 和 CXCR4 正常功能而导致的副作用。

DESCRIPTION (provided by applicant): Problems of drug resistance, latent viral reservoirs, and the toxic effects of current anti-HIV drugs call for the development of new anti-retrovirals with different modes of action. A promising approach for drug development is interference with the entry of HIV into cells. HIV entry is a complex process that requires binding of the HIV envelope protein gp120 to a cellular co-receptor (CCR5 or CXCR4). This proposal seeks to enhance understanding of the structure of CCR5 and CXCR4, including the amino acid residues that contribute to alternative modes of antagonist binding and contact residues involved in agonist activation. Virus isolates that require CCR5 for entry are the predominant infectious forms of HIV transmitted from one person to another. Virus strains that require CXCR4 for entry often emerge in the late stages of infection, are considered to be more pathogentic, and correlate with severe loss of CD4+ T lymphocytes and the development of opportunistic infections due to severe immunodeficiency. Several small-molecule antagonists for CCR5 or CXCR4 that block virus infection have been identified as promising drug leads by pharmaceutical companies, but their binding sites on the receptors and the mechanism of HIV blocking are poorly understood. This project will use high-affinity photoactive analogs of antagonist and agonist molecules to examine the interaction sites in CCR5 and CXCR4-and will investigate the roles of the residues at the crosslinking sites by site-specific mutagenesis. We will also investigate the changes in the conformation of CCR5 that result in activation or antagonism of HIV binding, by studying the interaction sites of monoclonal antibodies specific for the antagonist- or agonist-bound conformations of CCR5. The proposed studies will lead to a better understanding of the structure and function of CCR5 and CXCR4 and aim to provide information useful for the design of more potent drugs that inhibit HIV entry while minimizing side effects due to activating or blocking normal functions of CCR5 and CXCR4.