Butovskaya Elena, Soldà Paola, Scalabrin Matteo, Nadai Matteo, Richter Sara N
Department of Molecular Medicine , University of Padua , via Aristide Gabelli 63 , 35121 Padua , Italy.
ACS Infect Dis. 2019 Dec 13;5(12):2127-2135. doi: 10.1021/acsinfecdis.9b00272. Epub 2019 Nov 6.
The G-quadruplexes that form in the HIV-1 RNA genome hinder progression of reverse transcriptase in vitro, but not in infected cells. We investigated the possibility that the HIV-1 nucleocapsid protein NCp7, which remains associated with the viral RNA during reverse transcription, modulated HIV-1 RNA G-quadruplex stability. By electrophoresis, circular dichroism, mass spectrometry, and reverse transcriptase stop assays, we demonstrated that NCp7 binds and unfolds the HIV-1 RNA G-quadruplexes and promotes DNA/RNA duplex formation, allowing reverse transcription to proceed. The G-quadruplex ligand BRACO-19 was able to partially counteract this effect. These results indicate NCp7 as the first known viral protein able to unfold RNA G-quadruplexes, and they explain how the extra-stable HIV-1 RNA G-quadruplexes are processed; they also point out that the reverse transcription process is hindered by G-quadruplex ligands at both reverse transcriptase and NCp7 level. This information can lead to the development of more effective anti-HIV-1 drugs with a new mechanism of action.
在HIV-1 RNA基因组中形成的G-四链体在体外会阻碍逆转录酶的进程，但在受感染细胞中则不会。我们研究了HIV-1核衣壳蛋白NCp7在逆转录过程中与病毒RNA保持结合状态时，是否能调节HIV-1 RNA G-四链体稳定性的可能性。通过电泳、圆二色性、质谱分析和逆转录酶终止试验，我们证明NCp7能结合并解开HIV-1 RNA G-四链体，促进DNA/RNA双链体的形成，从而使逆转录得以进行。G-四链体配体BRACO-19能够部分抵消这种作用。这些结果表明NCp7是首个已知的能够解开RNA G-四链体的病毒蛋白，它们解释了超稳定的HIV-1 RNA G-四链体是如何被处理的；它们还指出，在逆转录酶和NCp7水平上，G-四链体配体都会阻碍逆转录过程。这一信息有助于开发具有新作用机制的更有效的抗HIV-1药物。
