Grigorov Boyan, Décimo Didier, Smagulova Fatima, Péchoux Christine, Mougel Marylène, Muriaux Delphine, Darlix Jean-Luc
LaboRetro, Unité de virologie humaine INSERM U758, IFR128, ENS, Lyon, France.
Retrovirology. 2007 Aug 3;4:54. doi: 10.1186/1742-4690-4-54.
The HIV-1 nucleocapsid protein (NC) is formed of two CCHC zinc fingers flanked by highly basic regions. HIV-1 NC plays key roles in virus structure and replication via its nucleic acid binding and chaperoning properties. In fact, NC controls proviral DNA synthesis by reverse transcriptase (RT), gRNA dimerization and packaging, and virion assembly.
We previously reported a role for the first NC zinc finger in virion structure and replication 1. To investigate the role of both NC zinc fingers in intracellular Gag trafficking, and in virion assembly, we generated series of NC zinc fingers mutations. Results show that all Zinc finger mutations have a negative impact on virion biogenesis and maturation and rendered defective the mutant viruses. The NC zinc finger mutations caused an intracellular accumulation of Gag, which was found either diffuse in the cytoplasm or at the plasma membrane but not associated with endosomal membranes as for wild type Gag. Evidences are also provided showing that the intracellular interactions between NC-mutated Gag and the gRNA were impaired.
These results show that Gag oligomerization mediated by gRNA-NC interactions is required for correct Gag trafficking, and assembly in HIV-1 producing cells and the release of infectious viruses.
HIV-1核衣壳蛋白（NC）由两个CCHC锌指结构组成，两侧为高度碱性区域。HIV-1 NC通过其核酸结合和伴侣活性在病毒结构和复制中发挥关键作用。事实上，NC通过逆转录酶（RT）控制前病毒DNA合成、gRNA二聚化和包装以及病毒体组装。
我们之前报道了第一个NC锌指在病毒体结构和复制中的作用。为了研究两个NC锌指在细胞内Gag转运和病毒体组装中的作用，我们产生了一系列NC锌指突变。结果表明，所有锌指突变对病毒体生物发生和成熟均有负面影响，使突变病毒存在缺陷。NC锌指突变导致Gag在细胞内积累，其在细胞质中呈弥漫性分布或位于质膜，但不像野生型Gag那样与内体膜相关。还提供了证据表明，NC突变的Gag与gRNA之间的细胞内相互作用受损。
这些结果表明，gRNA-NC相互作用介导的Gag寡聚化对于HIV-1产生细胞中正确的Gag转运、组装以及感染性病毒的释放是必需的。
