| Structural highlights
Function
[NEF_HV1A2] Factor of infectivity and pathogenicity, required for optimal virus replication. Alters numerous pathways of T-lymphocytes function and down-regulates immunity surface molecules in order to evade host defense and increase viral infectivity. Alters the functionality of other immunity cells, like dendritic cells, monocytes/macrophages and NK cells. One of the earliest and most abundantly expressed viral proteins (By similarity).[1] [2] [3] [4] [5] [6] In infected CD4(+) T-lymphocytes, down-regulates the surface MHC-I, mature MHC-II, CD4, CD28, CCR5 and CXCR4 molecules. Mediates internalization and degradation of host CD4 through the interaction of with the cytoplasmic tail of CD4, the recruitment of AP-2 (clathrin adapter protein complex 2), internalization through clathrin coated pits, and subsequent transport to endosomes and lysosomes for degradation. Diverts host MHC-I molecules to the trans-Golgi network-associated endosomal compartments by an endocytic pathway to finally target them for degradation. MHC-I down-regulation may involve AP-1 (clathrin adapter protein complex 1) or possibly Src family kinase-ZAP70/Syk-PI3K cascade recruited by PACS2. In consequence infected cells are masked for immune recognition by cytotoxic T-lymphocytes. Decreasing the number of immune receptors also prevents reinfection by more HIV particles (superinfection) (By similarity).[7] [8] [9] [10] [11] [12] Bypasses host T-cell signaling by inducing a transcriptional program nearly identical to that of anti-CD3 cell activation. Interaction with TCR-zeta chain up-regulates the Fas ligand (FasL). Increasing surface FasL molecules and decreasing surface MHC-I molecules on infected CD4(+) cells send attacking cytotoxic CD8+ T-lymphocytes into apoptosis (By similarity).[13] [14] [15] [16] [17] [18] Plays a role in optimizing the host cell environment for viral replication without causing cell death by apoptosis. Protects the infected cells from apoptosis in order to keep them alive until the next virus generation is ready to strike. Inhibits the Fas and TNFR-mediated death signals by blocking MAP3K5. Interacts and decreases the half-life of p53, protecting the infected cell against p53-mediated apoptosis. Inhibits the apoptotic signals regulated by the Bcl-2 family proteins through the formation of a Nef/PI3-kinase/PAK2 complex that leads to activation of PAK2 and induces phosphorylation of Bad (By similarity).[19] [20] [21] [22] [23] [24] Extracellular Nef protein targets CD4(+) T-lymphocytes for apoptosis by interacting with CXCR4 surface receptors (By similarity).[25] [26] [27] [28] [29] [30]
Publication Abstract from PubMed
The HIV-1 Nef accessory protein is essential for viral pathogenicity and AIDS progression. Nef forms complexes with multiple host cell factors to facilitate viral replication and promote immune escape of HIV-infected cells. Previous X-ray crystal structures demonstrate that Nef forms homodimers, the orientation of which are influenced by host cell binding partners. In cell-based fluorescence complementation assays, Nef forms homodimers at the plasma membrane. However, recombinant Nef proteins often exist as monomers in solution, suggesting that membrane interaction may also trigger monomer to dimer transitions. In this study, we show that monomeric Nef core proteins can be induced to form dimers in the presence of low concentrations of the non-ionic surfactant, beta-octyl glucoside (betaOG). X-ray crystallography revealed that a single betaOG molecule is present in the Nef dimer, with the 8-carbon acyl chain of the ligand binding to a hydrophobic pocket formed by the dimer interface. This Nef-betaOG dimer interface involves helix alphaB, as observed in previous dimer structures, as well as a helix formed by N-terminal residues 54-66. Nef dimer formation is stabilized in solution by the addition of betaOG, providing biochemical validation for the crystal structure. These observations together suggest that the interaction with host cell lipid mediators or other hydrophobic ligands may play a role in Nef dimerization, which has been previously linked to multiple Nef functions including host cell protein kinase activation, CD4 downregulation, and enhancement of HIV-1 replication.
A single beta-octyl glucoside molecule induces HIV-1 Nef dimer formation in the absence of partner protein binding.,Wu M, Alvarado JJ, Augelli-Szafran CE, Ptak RG, Smithgall TE PLoS One. 2018 Feb 7;13(2):e0192512. doi: 10.1371/journal.pone.0192512., eCollection 2018. PMID:29415006[31]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Briggs SD, Sharkey M, Stevenson M, Smithgall TE. SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1. J Biol Chem. 1997 Jul 18;272(29):17899-902. PMID:9218412
- ↑ Xu XN, Laffert B, Screaton GR, Kraft M, Wolf D, Kolanus W, Mongkolsapay J, McMichael AJ, Baur AS. Induction of Fas ligand expression by HIV involves the interaction of Nef with the T cell receptor zeta chain. J Exp Med. 1999 May 3;189(9):1489-96. PMID:10224289
- ↑ Kim YH, Chang SH, Kwon JH, Rhee SS. HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes. Virology. 1999 Apr 25;257(1):208-19. PMID:10208934 doi:S0042-6822(99)99642-3
- ↑ Arora VK, Molina RP, Foster JL, Blakemore JL, Chernoff J, Fredericksen BL, Garcia JV. Lentivirus Nef specifically activates Pak2. J Virol. 2000 Dec;74(23):11081-7. PMID:11070003
- ↑ Simmons A, Aluvihare V, McMichael A. Nef triggers a transcriptional program in T cells imitating single-signal T cell activation and inducing HIV virulence mediators. Immunity. 2001 Jun;14(6):763-77. PMID:11420046
- ↑ Wolf D, Witte V, Laffert B, Blume K, Stromer E, Trapp S, d'Aloja P, Schurmann A, Baur AS. HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals. Nat Med. 2001 Nov;7(11):1217-24. PMID:11689886 doi:10.1038/nm1101-1217
- ↑ Briggs SD, Sharkey M, Stevenson M, Smithgall TE. SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1. J Biol Chem. 1997 Jul 18;272(29):17899-902. PMID:9218412
- ↑ Xu XN, Laffert B, Screaton GR, Kraft M, Wolf D, Kolanus W, Mongkolsapay J, McMichael AJ, Baur AS. Induction of Fas ligand expression by HIV involves the interaction of Nef with the T cell receptor zeta chain. J Exp Med. 1999 May 3;189(9):1489-96. PMID:10224289
- ↑ Kim YH, Chang SH, Kwon JH, Rhee SS. HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes. Virology. 1999 Apr 25;257(1):208-19. PMID:10208934 doi:S0042-6822(99)99642-3
- ↑ Arora VK, Molina RP, Foster JL, Blakemore JL, Chernoff J, Fredericksen BL, Garcia JV. Lentivirus Nef specifically activates Pak2. J Virol. 2000 Dec;74(23):11081-7. PMID:11070003
- ↑ Simmons A, Aluvihare V, McMichael A. Nef triggers a transcriptional program in T cells imitating single-signal T cell activation and inducing HIV virulence mediators. Immunity. 2001 Jun;14(6):763-77. PMID:11420046
- ↑ Wolf D, Witte V, Laffert B, Blume K, Stromer E, Trapp S, d'Aloja P, Schurmann A, Baur AS. HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals. Nat Med. 2001 Nov;7(11):1217-24. PMID:11689886 doi:10.1038/nm1101-1217
- ↑ Briggs SD, Sharkey M, Stevenson M, Smithgall TE. SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1. J Biol Chem. 1997 Jul 18;272(29):17899-902. PMID:9218412
- ↑ Xu XN, Laffert B, Screaton GR, Kraft M, Wolf D, Kolanus W, Mongkolsapay J, McMichael AJ, Baur AS. Induction of Fas ligand expression by HIV involves the interaction of Nef with the T cell receptor zeta chain. J Exp Med. 1999 May 3;189(9):1489-96. PMID:10224289
- ↑ Kim YH, Chang SH, Kwon JH, Rhee SS. HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes. Virology. 1999 Apr 25;257(1):208-19. PMID:10208934 doi:S0042-6822(99)99642-3
- ↑ Arora VK, Molina RP, Foster JL, Blakemore JL, Chernoff J, Fredericksen BL, Garcia JV. Lentivirus Nef specifically activates Pak2. J Virol. 2000 Dec;74(23):11081-7. PMID:11070003
- ↑ Simmons A, Aluvihare V, McMichael A. Nef triggers a transcriptional program in T cells imitating single-signal T cell activation and inducing HIV virulence mediators. Immunity. 2001 Jun;14(6):763-77. PMID:11420046
- ↑ Wolf D, Witte V, Laffert B, Blume K, Stromer E, Trapp S, d'Aloja P, Schurmann A, Baur AS. HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals. Nat Med. 2001 Nov;7(11):1217-24. PMID:11689886 doi:10.1038/nm1101-1217
- ↑ Briggs SD, Sharkey M, Stevenson M, Smithgall TE. SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1. J Biol Chem. 1997 Jul 18;272(29):17899-902. PMID:9218412
- ↑ Xu XN, Laffert B, Screaton GR, Kraft M, Wolf D, Kolanus W, Mongkolsapay J, McMichael AJ, Baur AS. Induction of Fas ligand expression by HIV involves the interaction of Nef with the T cell receptor zeta chain. J Exp Med. 1999 May 3;189(9):1489-96. PMID:10224289
- ↑ Kim YH, Chang SH, Kwon JH, Rhee SS. HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes. Virology. 1999 Apr 25;257(1):208-19. PMID:10208934 doi:S0042-6822(99)99642-3
- ↑ Arora VK, Molina RP, Foster JL, Blakemore JL, Chernoff J, Fredericksen BL, Garcia JV. Lentivirus Nef specifically activates Pak2. J Virol. 2000 Dec;74(23):11081-7. PMID:11070003
- ↑ Simmons A, Aluvihare V, McMichael A. Nef triggers a transcriptional program in T cells imitating single-signal T cell activation and inducing HIV virulence mediators. Immunity. 2001 Jun;14(6):763-77. PMID:11420046
- ↑ Wolf D, Witte V, Laffert B, Blume K, Stromer E, Trapp S, d'Aloja P, Schurmann A, Baur AS. HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals. Nat Med. 2001 Nov;7(11):1217-24. PMID:11689886 doi:10.1038/nm1101-1217
- ↑ Briggs SD, Sharkey M, Stevenson M, Smithgall TE. SH3-mediated Hck tyrosine kinase activation and fibroblast transformation by the Nef protein of HIV-1. J Biol Chem. 1997 Jul 18;272(29):17899-902. PMID:9218412
- ↑ Xu XN, Laffert B, Screaton GR, Kraft M, Wolf D, Kolanus W, Mongkolsapay J, McMichael AJ, Baur AS. Induction of Fas ligand expression by HIV involves the interaction of Nef with the T cell receptor zeta chain. J Exp Med. 1999 May 3;189(9):1489-96. PMID:10224289
- ↑ Kim YH, Chang SH, Kwon JH, Rhee SS. HIV-1 Nef plays an essential role in two independent processes in CD4 down-regulation: dissociation of the CD4-p56(lck) complex and targeting of CD4 to lysosomes. Virology. 1999 Apr 25;257(1):208-19. PMID:10208934 doi:S0042-6822(99)99642-3
- ↑ Arora VK, Molina RP, Foster JL, Blakemore JL, Chernoff J, Fredericksen BL, Garcia JV. Lentivirus Nef specifically activates Pak2. J Virol. 2000 Dec;74(23):11081-7. PMID:11070003
- ↑ Simmons A, Aluvihare V, McMichael A. Nef triggers a transcriptional program in T cells imitating single-signal T cell activation and inducing HIV virulence mediators. Immunity. 2001 Jun;14(6):763-77. PMID:11420046
- ↑ Wolf D, Witte V, Laffert B, Blume K, Stromer E, Trapp S, d'Aloja P, Schurmann A, Baur AS. HIV-1 Nef associated PAK and PI3-kinases stimulate Akt-independent Bad-phosphorylation to induce anti-apoptotic signals. Nat Med. 2001 Nov;7(11):1217-24. PMID:11689886 doi:10.1038/nm1101-1217
- ↑ Wu M, Alvarado JJ, Augelli-Szafran CE, Ptak RG, Smithgall TE. A single beta-octyl glucoside molecule induces HIV-1 Nef dimer formation in the absence of partner protein binding. PLoS One. 2018 Feb 7;13(2):e0192512. doi: 10.1371/journal.pone.0192512., eCollection 2018. PMID:29415006 doi:http://dx.doi.org/10.1371/journal.pone.0192512
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