Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.
PLoS Pathog. 2010 Nov 24;6(11):e1001173. doi: 10.1371/journal.ppat.1001173.
The structure of immature and mature HIV-1 particles has been analyzed in detail by cryo electron microscopy, while no such studies have been reported for cellular HIV-1 budding sites. Here, we established a system for studying HIV-1 virus-like particle assembly and release by cryo electron tomography of intact human cells. The lattice of the structural Gag protein in budding sites was indistinguishable from that of the released immature virion, suggesting that its organization is determined at the assembly site without major subsequent rearrangements. Besides the immature lattice, a previously not described Gag lattice was detected in some budding sites and released particles; this lattice was found at high frequencies in a subset of infected T-cells. It displays the same hexagonal symmetry and spacing in the MA-CA layer as the immature lattice, but lacks density corresponding to NC-RNA-p6. Buds and released particles carrying this lattice consistently lacked the viral ribonucleoprotein complex, suggesting that they correspond to aberrant products due to premature proteolytic activation. We hypothesize that cellular and/or viral factors normally control the onset of proteolytic maturation during assembly and release, and that this control has been lost in a subset of infected T-cells leading to formation of aberrant particles.
通过低温电子显微镜对不成熟和成熟 HIV-1 颗粒的结构进行了详细分析，而对于细胞 HIV-1 出芽部位则没有此类研究报告。在这里，我们通过对完整人类细胞的低温电子断层扫描，建立了一个研究 HIV-1 病毒样颗粒组装和释放的系统。出芽部位结构 Gag 蛋白的晶格与释放的不成熟病毒粒子的晶格无法区分，这表明其组织在组装部位确定，没有重大的后续重排。除了不成熟的晶格，在一些出芽部位和释放的颗粒中还检测到了以前未描述的 Gag 晶格；在一组受感染的 T 细胞中，这种晶格以高频率出现。它在 MA-CA 层中显示出与不成熟晶格相同的六方对称性和间距，但缺乏与 NC-RNA-p6 相对应的密度。带有这种晶格的芽和释放的颗粒一致缺乏病毒核糖核蛋白复合物，这表明它们对应于过早的蛋白水解激活导致的异常产物。我们假设细胞和/或病毒因素通常控制组装和释放过程中蛋白水解成熟的开始，而在一组受感染的 T 细胞中，这种控制已经丢失，导致异常颗粒的形成。
