A Flexible Approach to Inhibiting HIV NCp7

 描述（由申请人提供）：抗病毒药物的广泛使用导致出现了对目前可用的核苷治疗剂具有抗性的突变病毒株。使用靶向不同病毒酶的药物组合（称为高效抗逆转录病毒疗法或HAART）有所帮助，但不良副作用和毒性通常普遍存在，多药耐药的报告正在增加。因此，对新的病毒酶靶点的需求至关重要。在这方面，HIV的核衣壳蛋白提供了一个有吸引力的靶标。NCp 7是一种小的锌结合蛋白，已被证明在HIV-1复制过程的早期和晚期都是至关重要的。NCp 7（和Gag前体多聚蛋白的NCp 7结构域）在HIV复制中具有几个关键作用，包括直接参与RNA基因组识别和包装，促进tRNA引物退火以启动逆转录，以及促进逆转录期间的链转移。NCp 7含有两个CCHC型锌指结构域，在复制过程中发挥关键的RNA结合作用，并且破坏锌配位的单原子Cys到Ser突变足以完全阻断病毒复制。已经尝试了几种设计抑制剂的方法，最常见的是使用锌喷射器，然而迄今为止，这些方法表现出显著的毒性和差的特异性。这一问题阻碍了确定可行的 抑制剂是蛋白质本身固有的灵活性。因此，在Seley-Radtke实验室中设计和开发的柔性核苷（称为“fleximers”）可以提供解决方案。在这方面，已经通过虚拟筛选方法鉴定了一系列NCp 7的柔性核碱基（“flexbase”）抑制剂。flexbase类似物与已知对NCp 7的生物学相关构象至关重要的中心鸟苷残基具有极好的比对，因此形成了本申请的基础。值得注意的是，柔性基底不应导致锌喷射，从而克服与其他方法相关的问题。

 DESCRIPTION (provided by applicant): The extensive use of antiviral drugs has resulted in the emergence of mutant viral strains that are resistant to the currently available nucleoside therapeutics. Using a combination of drugs that target different viral enzymes (termed highly active anti-retroviral therapy or HAART) has helped, however undesirable side effects and toxicity are often prevalent and reports of multidrug resistance are increasing. As a result, the need for new viral enzymatic targets is critical. In that regard, the nucleocapsid protein of HIV offers forth an attractive target. NCp7 is a small zinc-binding protein that has been shown to be critical in both the early and late stages of the HIV-1 replication process. NCp7 (and the NCp7 domain of the Gag precursor polyprotein) has several key roles in HIV replication, including direct participation in RNA genome recognition and packaging, promoting annealing of the tRNA primer to initiate reverse transcription, and facilitating strand transfer during reverse transcription. NCp7 contains two CCHC-type zinc finger domains that play critical RNA-binding roles during replication, and single-atom Cys-to-Ser mutations that disrupt zinc coordination are sufficient to completely block viral replication. Several approaches to designing inhibitors have been tried, most commonly, use of zinc-ejectors, however to date these have exhibited significant toxicity and poor specificity. A problem that has hindered the identification of viable inhibitors is the inherent flexibility of the protein itself. As such, flexible nucleosides, known s "fleximers" designed and developed in the Seley-Radtke laboratory may provide a solution. In that regard, a series of flexible nucleobase ("flexbase") inhibitors of NCp7 have been identified by means of a virtual screening process. The flexbase analogues are in excellent alignment with the central guanosine residue known to be critical to the biologically relevant conformations of NCp7, thus form the basis for this application. Notably, the flexbases should not result in zinc ejection thereby overcoming the problems associated with other approaches.