CCR5 & CXCR4 Antagonist & Agonist Binding Site Structure

描述(由申请人提供)： 耐药性问题、潜在的病毒库以及当前抗艾滋病毒药物的毒性作用要求开发具有不同作用模式的新的抗逆转录病毒药物。一种有希望的药物开发方法是干扰艾滋病毒进入细胞。HIV进入是一个复杂的过程，需要将HIV包膜蛋白gp120与细胞共受体(CCR5或CXCR4)结合。这一建议旨在加强对CCR5和CXCR4结构的理解，包括有助于拮抗剂结合的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进入的病毒分离株是艾滋病毒从一个人传播到另一个人的主要感染形式。需要CXCR4进入的病毒株通常出现在感染的晚期，被认为更具致病性，与CD4T淋巴细胞的严重丧失和由于严重的免疫缺陷而发生机会性感染有关。几种阻断病毒感染的CCR5或CXCR4小分子拮抗剂已被制药公司确定为有希望的药物先导，但它们在受体上的结合位置和阻断HIV的机制尚不清楚。该项目将使用高亲和力的拮抗剂和激动剂分子的光活性类似物来研究CCR5和CXCR4中的相互作用部位，并将通过定点突变来研究交联点上残基的作用。我们还将通过研究针对CCR5拮抗剂或激动剂结合构象的单抗的相互作用位点，来研究导致HIV结合的激活或拮抗的CCR5构象的变化。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，这些药物可以抑制艾滋病毒进入，同时最大限度地减少由于激活或阻断CCR5和CXCR4的正常功能而产生的副作用。

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.