1x9v
From Proteopedia
Dimeric structure of the C-terminal domain of Vpr
Structural highlights
Function[VPR_HV1B9] 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). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHIV-1 Vpr is a highly conserved accessory protein that is involved in many functions of the virus life cycle. Vpr facilitates the entry of the HIV pre-integration complex through the nuclear pore, induces G2 cell cycle arrest, regulates cell apoptosis, increases transcription from the long terminal repeat and enhances viral replication. Vpr contains a Leu/Ile-rich domain (amino acids 60-81) in its C-terminal part, which is critical for dimerization. The sequence comprising residues 52-96 is implicated in properties of the protein such as DNA interaction and apoptosis via interaction with the adenine nucleotide translocator. To understand the specific interactions of Vpr-(52-96), the ability of this peptide to dimerize via a leucine-zipper mechanism has been investigated, by NMR and fluorescence spectroscopy. In contrast with results from a study performed in the presence of trifluoroethanol, our results, obtained in 30% (v/v) [2H]acetonitrile, show that Vpr-(52-96) in solution still forms an a-helix spanning residues 53-75, but dimerizes in an antiparallel orientation, through hydrophobic interactions between leucine and isoleucine residues and stacking between His71 and Trp54. Moreover, to demonstrate the physiological relevance of the dimer structure, fluorescence spectroscopy experiments have been performed in a Mes buffer, which confirmed the formation of the dimer in aqueous solution and highlighted the spatial proximity between Trp54 and His71. Surprisingly, the leucine-zipper structure shown in the present work for Vpr-(52-96) mimics the structure of full-length Vpr-(1-96), and this could explain why some of the properties of Vpr-(52-96) and Vpr-(1-96) are identical, while some are even enhanced for Vpr-(52-96), particularly in the case of DNA transfection experiments. The C-terminal domain of the HIV-1 regulatory protein Vpr adopts an antiparallel dimeric structure in solution via its leucine-zipper-like domain.,Bourbigot S, Beltz H, Denis J, Morellet N, Roques BP, Mely Y, Bouaziz S Biochem J. 2005 Apr 15;387(Pt 2):333-41. PMID:15571493[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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