We report the crystal structure of the SARS-CoV-2 putative primase composed of the nsp7 and nsp8 proteins. We observed a dimer of dimers (2:2 nsp7-nsp8) in the crystallographic asymmetric unit. The structure revealed a fold with a helical core of the heterotetramer formed by both nsp7 and nsp8 that is flanked with two symmetry-related nsp8 β-sheet subdomains. It was also revealed that two hydrophobic interfaces one of approx. 1340 Å² connects the nsp7 to nsp8 and a second one of approx. 950 Å² connects the dimers and form the observed heterotetramer. Interestingly, analysis of the surface electrostatic potential revealed a putative RNA binding site that is formed only within the heterotetramer.

我们报告了由nsp7和nsp8蛋白质组成的SARS-CoV-2假定的启动酶的晶体结构。我们在晶体学不对称单元中观察到二聚体的二聚体（2：2 nsp7-nsp8）。该结构揭示了由nsp7和nsp8形成的具有异源四聚体螺旋核心的折叠，其侧翼是两个对称相关的nsp8β-sheet子域。还揭示了两个疏水性界面之一为约。1340埃²连接到nsp7的和nsp8大约的第二个。950 ²连接二聚体和形成异四聚观察。有趣的是，对表面静电势的分析揭示了仅在异四聚体内形成的假定的RNA结合位点。