Baranovskiy Andrey G, Morstadt Lucia M, Babayeva Nigar D, Tahirov Tahir H
Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA.
bioRxiv. 2024 Sep 5:2024.09.03.608162. doi: 10.1101/2024.09.03.608162.
The human primosome, a four-subunit complex of DNA primase and DNA polymerase alpha (Polα), plays a critical role in DNA replication by initiating RNA and DNA synthesis on both chromosome strands. A recent study has shown that a major virulence factor in the SARS-CoV-2 infection, Nsp1 (non-structural protein 1), forms a stable complex with Polα but does not affect the primosome activity. Here we show that Nsp1 inhibits DNA synthesis across inverted repeats prone to hairpin formation. Analysis of current structural data revealed the overlapping binding sites for Nsp1 and the winged helix-turn-helix domain of RPA (wHTH) on Polα, indicating a competition between them. Comparison of the inhibitory effect of Nsp1 and wHTH on DNA hairpin bypass by Polα showed an 8-fold lower IC value for Nsp1 (1 μM). This study provides a valuable insight into the mechanism of inhibition of human DNA replication by Nsp1 during a SARS-CoV-2 infection.
人类引发体是一种由DNA引发酶和DNA聚合酶α（Polα）组成的四亚基复合物，通过在两条染色体链上启动RNA和DNA合成，在DNA复制中发挥关键作用。最近的一项研究表明，严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染中的一种主要毒力因子Nsp1（非结构蛋白1）与Polα形成稳定复合物，但不影响引发体活性。在此我们表明，Nsp1抑制易形成发夹结构的反向重复序列上的DNA合成。对当前结构数据的分析揭示了Nsp1和RPA（wHTH）的翼状螺旋-转角-螺旋结构域在Polα上的重叠结合位点，表明它们之间存在竞争。Nsp1和wHTH对Polα绕过DNA发夹的抑制作用比较显示，Nsp1的半数抑制浓度（IC）值低8倍（1μM）。这项研究为SARS-CoV-2感染期间Nsp1抑制人类DNA复制的机制提供了有价值的见解。
