Zhao L J, Wang L, Mukherjee S, Narayan O
Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City 66160-7424.
J Biol Chem. 1994 Dec 23;269(51):32131-7.
The human immunodeficiency virus, type 1 (HIV-1) genome encodes a 15-kDa accessory gene product, Vpr, that is essential for virus replication in primary monocytes/macrophages. Being present in the virion, Vpr is believed to function in the early phases of HIV-1 replication, including nuclear migration of the pre-integration complex and/or transcription of the provirus genome. By gel filtration analysis of highly purified Vpr protein and its mutants, we demonstrate that HIV-1 Vpr exists as an oligomer. The N-terminal domain of Vpr (amino acids (aa) 1-42) is sufficient for oligomerization; however, deletion of aa 36-76 from Vpr disrupts oligomerization, suggesting that aa 36-42 are critical for Vpr oligomerization. As a result of Vpr oligomerization, basic aa residues within Vpr aa 1-73 are highly resistant to trypsin digestion, while those within Vpr aa 74-96 are easily accessible. Mutations within the leucine-/isoleucine-rich domain (aa 60-81), which was previously identified to be involved in Vpr interaction with a host cellular protein, rendered Arg62 more susceptible to trypsin digestion. Thus, the Vpr oligomeric structure must be extended into this domain. These results suggest a novel feature of HIV-1 Vpr that may be important for its functions.
1型人类免疫缺陷病毒（HIV-1）基因组编码一种15千道尔顿的辅助基因产物Vpr，它对于病毒在原代单核细胞/巨噬细胞中的复制至关重要。Vpr存在于病毒粒子中，被认为在HIV-1复制的早期阶段发挥作用，包括整合前复合物的核迁移和/或原病毒基因组的转录。通过对高度纯化的Vpr蛋白及其突变体进行凝胶过滤分析，我们证明HIV-1 Vpr以寡聚体形式存在。Vpr的N端结构域（氨基酸（aa）1 - 42）足以形成寡聚体；然而，从Vpr中缺失aa 36 - 76会破坏寡聚化，这表明aa 36 - 42对Vpr寡聚化至关重要。由于Vpr寡聚化，Vpr aa 1 - 73内的碱性氨基酸残基对胰蛋白酶消化具有高度抗性，而Vpr aa 74 - 96内的那些残基则易于被消化。先前已确定富含亮氨酸/异亮氨酸的结构域（aa 60 - 81）参与Vpr与宿主细胞蛋白的相互作用，该结构域内的突变使Arg62更容易被胰蛋白酶消化。因此，Vpr寡聚体结构必定延伸至该结构域。这些结果提示了HIV-1 Vpr的一个新特性，这可能对其功能很重要。
