Biochemical mechanism of HIV-1 Vpr function. Oligomerization mediated by the N-terminal domain.
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.
Zhao
L J
LJ
Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City 66160-7424.
Wang
L
L
Mukherjee
S
S
Narayan
O
O
D000595:Amino Acid Sequence; D001704:Biopolymers; D015153:Blotting, Western; D002850:Chromatography, Gel; D016336:Gene Products, vpr / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014357:Trypsin / Q000378:metabolism; D054325:vpr Gene Products, Human Immunodeficiency Virus
D001704:Biopolymers; D016336:Gene Products, vpr; D054325:vpr Gene Products, Human Immunodeficiency Virus; D014357:Trypsin