Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA. Electronic address: https://twitter.com/BioChemTalledge.
Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA.
J Mol Biol. 2023 Aug 1;435(15):168143. doi: 10.1016/j.jmb.2023.168143. Epub 2023 May 6.
Retrovirus immature particle morphology consists of a membrane enclosed, pleomorphic, spherical and incomplete lattice of Gag hexamers. Previously, we demonstrated that human immunodeficiency virus type 2 (HIV-2) immature particles possess a distinct and extensive Gag lattice morphology. To better understand the nature of the continuously curved hexagonal Gag lattice, we have used the single particle cryo-electron microscopy method to determine the HIV-2 Gag lattice structure for immature virions. The reconstruction map at 5.5 Å resolution revealed a stable, wineglass-shaped Gag hexamer structure with structural features consistent with other lentiviral immature Gag lattice structures. Cryo-electron tomography provided evidence for nearly complete ordered Gag lattice structures in HIV-2 immature particles. We also solved a 1.98 Å resolution crystal structure of the carboxyl-terminal domain (CTD) of the HIV-2 capsid (CA) protein that identified a structured helix 12 supported via an interaction of helix 10 in the absence of the SP1 region of Gag. Residues at the helix 10-12 interface proved critical in maintaining HIV-2 particle release and infectivity. Taken together, our findings provide the first 3D organization of HIV-2 immature Gag lattice and important insights into both HIV Gag lattice stabilization and virus maturation.
逆转录病毒不成熟颗粒的形态由一个包裹着膜的、多形的、球形的和不完全的 Gag 六聚体晶格组成。此前，我们已经证明，人类免疫缺陷病毒 2 型（HIV-2）不成熟颗粒具有独特而广泛的 Gag 晶格形态。为了更好地了解连续弯曲的六边形 Gag 晶格的性质，我们使用单颗粒冷冻电镜方法来确定 HIV-2 Gag 晶格结构的不成熟病毒。分辨率为 5.5 Å 的重建图谱显示了一个稳定的、酒杯状的 Gag 六聚体结构，其结构特征与其他慢病毒不成熟 Gag 晶格结构一致。冷冻电镜断层摄影术为 HIV-2 不成熟颗粒中几乎完全有序的 Gag 晶格结构提供了证据。我们还解析了 HIV-2 衣壳（CA）蛋白羧基末端结构域（CTD）的 1.98 Å 分辨率晶体结构，该结构确定了一个有结构的螺旋 12，其通过在没有 Gag 的 SP1 区域的情况下，与螺旋 10 相互作用来支持。螺旋 10-12 界面处的残基对于维持 HIV-2 颗粒释放和感染性至关重要。总之，我们的发现提供了 HIV-2 不成熟 Gag 晶格的第一个 3D 组织，并为 HIV Gag 晶格的稳定和病毒成熟提供了重要的见解。
