Dipartimento di Scienze del Farmaco , Università di Padova , via Marzolo 5 , 35131 Padova , Italy.
Dipartimento di Farmacia , Università degli Studi di Napoli "Federico II" , Via D. Montesano 49 , 80131 Napoli , Italy.
Bioconjug Chem. 2018 Jul 18;29(7):2195-2207. doi: 10.1021/acs.bioconjchem.8b00104. Epub 2018 Jun 12.
The HIV-1 nucleocapsid (NC) protein represents an excellent molecular target for the development of anti-retrovirals by virtue of its well-characterized chaperone activities, which play pivotal roles in essential steps of the viral life cycle. Our ongoing search for candidates able to impair NC binding/annealing activities led to the identification of peptidyl-anthraquinones as a promising class of nucleic acid ligands. Seeking to elucidate the inhibition determinants and increase the potency of this class of compounds, we have now explored the effects of chirality in the linker connecting the planar nucleus to the basic side chains. We show here that the non-natural linker configuration imparted unexpected TAR RNA targeting properties to the 2,6-peptidyl-anthraquinones and significantly enhanced their potency. Even if the new compounds were able to interact directly with the NC protein, they manifested a consistently higher affinity for the TAR RNA substrate and their TAR-binding properties mirrored their ability to interfere with NC-TAR interactions. Based on these findings, we propose that the viral Tat protein, sharing the same RNA substrate but acting in distinct phases of the viral life cycle, constitutes an additional druggable target for this class of peptidyl-anthraquinones. The inhibition of Tat-TAR interaction for the test compounds correlated again with their TAR-binding properties, while simultaneously failing to demonstrate any direct Tat-binding capabilities. These considerations highlighted the importance of TAR RNA in the elucidation of their inhibition mechanism, rather than direct protein inhibition. We have therefore identified anti-TAR compounds with dual in vitro inhibitory activity on different viral proteins, demonstrating that it is possible to develop multitarget compounds capable of interfering with processes mediated by the interactions of this essential RNA domain of HIV-1 genome with NC and Tat proteins.
HIV-1 核衣壳（NC）蛋白因其特征明确的伴侣活性而成为开发抗逆转录病毒药物的极佳分子靶标，这些伴侣活性在病毒生命周期的关键步骤中发挥着重要作用。我们一直在寻找能够损害 NC 结合/退火活性的候选物，这导致了肽基蒽醌类作为一种有前途的核酸配体类别的出现。为了阐明抑制决定因素并提高这类化合物的效力，我们现在已经探索了连接平面核与碱性侧链的连接子中的手性的影响。我们在这里表明，非天然连接子构型赋予了 2,6-肽基蒽醌类化合物对 TAR RNA 的靶向性质，并显著提高了它们的效力。即使新化合物能够直接与 NC 蛋白相互作用，它们对 TAR RNA 底物表现出更高的亲和力，并且它们的 TAR 结合特性反映了它们干扰 NC-TAR 相互作用的能力。基于这些发现，我们提出病毒 Tat 蛋白与相同的 RNA 底物共享，但在病毒生命周期的不同阶段发挥作用，构成了这类肽基蒽醌类化合物的另一个可成药靶标。测试化合物对 Tat-TAR 相互作用的抑制作用再次与其 TAR 结合特性相关，同时未能证明它们具有任何直接的 Tat 结合能力。这些考虑因素强调了 TAR RNA 在阐明其抑制机制中的重要性，而不是直接的蛋白质抑制。因此，我们已经确定了具有针对不同病毒蛋白的双重体外抑制活性的抗 TAR 化合物，证明了开发能够干扰 HIV-1 基因组这一关键 RNA 结构域与 NC 和 Tat 蛋白相互作用介导的过程的多靶标化合物是可能的。
