Structural highlights
Function
[VPR_HV1N5] Involved in the transport of the viral pre-integration (PIC) complex to the nucleus during the early stages of the infection. This function is crucial for viral infection of non-dividing macrophages. May interact with karyopherin alpha/KPNA1 and KPNA2 to increase their affinity for proteins containing basic-type nuclear localization signal, including the viral matrix protein MA, thus facilitating the translocation of the viral genome into the nucleus. May also act directly at the nuclear pore complex, by binding nucleoporins phenylalanine-glycine (FG)-repeat regions (By similarity). May target specific host proteins for degradation by the 26S proteasome. Acts by associating with the cellular CUL4A-DDB1 E3 ligase complex through direct interaction with host VPRPB/DCAF-1. This change in the E3 ligase substrate specificity would result in cell cycle arrest or apoptosis in infected cells. Prevents infected cells from undergoing mitosis and proliferating, by inducing arrest or delay in the G2 phase of the cell cycle. This arrest creates a favorable environment for maximizing viral expression and production by rendering the HIV-1 LTR transcriptionally more active. In this context, Vpr stimulates gene expression driven by the HIV-1 LTR by interacting with human SP1, TFIIB and TFIID. Cell cycle arrest reportedly occurs within hours of infection and is not blocked by antiviral agents, suggesting that it is initiated by the Vpr carried into the virion. Additionally, Vpr induces apoptosis in a cell cycle dependent manner suggesting that these two effects are mechanistically linked. Interacts with mitochondrial permeability transition pore complex (PTPC). This interaction induces a rapid dissipation of the mitochondrial transmembrane potential, and mitochondrial release of apoptogenic proteins such as cytochrome C or apoptosis inducing factors. Detected in the serum and cerebrospinal fluid of AIDS patient, Vpr may also induce cell death to bystander cells (By similarity).
Publication Abstract from PubMed
Vpr, one of the accessory gene products encoded by HIV-1, is a 96-residue protein with a number of functions, including targeting of the viral pre-integration complex to the nucleus and inducing growth arrest of dividing cells. We have characterized by 2D NMR the solution conformations of bioactive synthetic peptide fragments of Vpr encompassing a pair of H(F/S)RIG sequence motifs (residues 71-75 and 78-82 of HIV-1 Vpr) that cause cell membrane permeabilization and death in yeast and mammalian cells. Due to limited solubility of the peptides in water, their structures were studied in aqueous trifluoroethanol. Peptide Vpr59-86 (residues 59-86 of Vpr) formed an alpha-helix encompassing residues 60-77, with a kink in the vicinity of residue 62. The first of the repeated sequence motifs (HFRIG) participated in the well-defined alpha-helical domain whereas the second (HSRIG) lay outside the helical domain and formed a reverse turn followed by a less ordered region. On the other hand, peptides Vpr71-82 and Vpr71-96, in which the sequence motifs were located at the N-terminus, were largely unstructured under similar conditions, as judged by their C(alpha)H chemical shifts. Thus, the HFRIG and HSRIG motifs adopt alpha-helical and turn structures, respectively, when preceded by a helical structure, but are largely unstructured in isolation. The implications of these findings for interpretation of the structure-function relationships of synthetic peptides containing these motifs are discussed.
Solution structure of peptides from HIV-1 Vpr protein that cause membrane permeabilization and growth arrest.,Yao S, Torres AM, Azad AA, Macreadie IG, Norton RS J Pept Sci. 1998 Nov;4(7):426-35. PMID:9851370[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Yao S, Torres AM, Azad AA, Macreadie IG, Norton RS. Solution structure of peptides from HIV-1 Vpr protein that cause membrane permeabilization and growth arrest. J Pept Sci. 1998 Nov;4(7):426-35. PMID:9851370 doi:<426::AID-PSC161>3.0.CO;2-J 10.1002/(SICI)1099-1387(199811)4:7<426::AID-PSC161>3.0.CO;2-J
