scholarly journals APOBEC3F and APOBEC3G Inhibit HIV-1 DNA Integration by Different Mechanisms

2010 ◽  
Vol 84 (10) ◽  
pp. 5250-5259 ◽  
Author(s):  
Jean L. Mbisa ◽  
Wei Bu ◽  
Vinay K. Pathak
Keyword(s):  
Catalytic Domain ◽  
Restriction Factors ◽  
Viral Dna ◽  
Dna Integration ◽  
Host Restriction ◽  
Antiviral Activities ◽  
Viral Cdna ◽  
Viral Dna Integration ◽  
Cytidine Deamination ◽  
Hiv 1

ABSTRACT APOBEC3F (A3F) and APBOBEC3G (A3G) both are host restriction factors that can potently inhibit human immunodeficiency virus type 1 (HIV-1) replication. Their antiviral activities are at least partially mediated by cytidine deamination, which causes lethal mutations of the viral genome. We recently showed that A3G blocks viral plus-strand DNA transfer and inhibits provirus establishment in the host genome (J. L. Mbisa, R. Barr, J. A. Thomas, N. Vandegraaff, I. J. Dorweiler, E. S. Svarovskaia, W. L. Brown, L. M. Mansky, R. J. Gorelick, R. S. Harris, A. Engelman, and V. K. Pathak, J. Virol. 81:7099-7110, 2007). Here, we investigated whether A3F similarly interferes with HIV-1 provirus formation. We observed that both A3F and A3G inhibit viral DNA synthesis and integration, but A3F is more potent than A3G in preventing viral DNA integration. We further investigated the mechanisms by which A3F and A3G block viral DNA integration by analyzing their effects on viral cDNA processing using Southern blot analysis. A3G generates a 6-bp extension at the viral U5 end of the 3′ long terminal repeat (3′-LTR), which is a poor substrate for integration; in contrast, A3F inhibits viral DNA integration by reducing the 3′ processing of viral DNA at both the U5 and U3 ends. Furthermore, we demonstrated that a functional C-terminal catalytic domain is more critical for A3G than A3F function in blocking HIV-1 provirus formation. Finally, we showed that A3F has a greater binding affinity for a viral 3′-LTR double-stranded DNA (dsDNA) oligonucleotide template than A3G. Taking these results together, we demonstrated that mechanisms utilized by A3F to prevent HIV-1 viral DNA integration were different from those of A3G, and that their target specificities and/or their affinities for dsDNA may contribute to their distinct mechanisms.

scholarly journals Binding to DCAF1 distinguishes TASOR and SAMHD1 degradation by HIV-2 Vpx

2021 ◽  
Vol 17 (10) ◽  
pp. e1009609
Author(s):  
Michaël M. Martin ◽  
Roy Matkovic ◽  
Pauline Larrous ◽  
Marina Morel ◽  
Angélique Lasserre ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Restriction Factors ◽  
Viral Dna ◽  
Host Restriction ◽  
Viral Expression ◽  
Host Restriction Factors ◽  
Human Immunodeficiency Viruses ◽  
Hiv 1

Human Immunodeficiency viruses type 1 and 2 (HIV-1 and HIV-2) succeed to evade host immune defenses by using their viral auxiliary proteins to antagonize host restriction factors. HIV-2/SIVsmm Vpx is known for degrading SAMHD1, a factor impeding the reverse transcription. More recently, Vpx was also shown to counteract HUSH, a complex constituted of TASOR, MPP8 and periphilin, which blocks viral expression from the integrated viral DNA. In a classical ubiquitin ligase hijacking model, Vpx bridges the DCAF1 ubiquitin ligase substrate adaptor to SAMHD1, for subsequent ubiquitination and degradation. Here, we investigated whether the same mechanism is at stake for Vpx-mediated HUSH degradation. While we confirm that Vpx bridges SAMHD1 to DCAF1, we show that TASOR can interact with DCAF1 in the absence of Vpx. Nonetheless, this association was stabilized in the presence of Vpx, suggesting the existence of a ternary complex. The N-terminal PARP-like domain of TASOR is involved in DCAF1 binding, but not in Vpx binding. We also characterized a series of HIV-2 Vpx point mutants impaired in TASOR degradation, while still degrading SAMHD1. Vpx mutants ability to degrade TASOR correlated with their capacity to enhance HIV-1 minigenome expression as expected. Strikingly, several Vpx mutants impaired for TASOR degradation, but not for SAMHD1 degradation, had a reduced binding affinity for DCAF1, but not for TASOR. In macrophages, Vpx R34A-R42A and Vpx R42A-Q47A-V48A, strongly impaired in DCAF1, but not in TASOR binding, could not degrade TASOR, while being efficient in degrading SAMHD1. Altogether, our results highlight the central role of a robust Vpx-DCAF1 association to trigger TASOR degradation. We then propose a model in which Vpx interacts with both TASOR and DCAF1 to stabilize a TASOR-DCAF1 complex. Furthermore, our work identifies Vpx mutants enabling the study of HUSH restriction independently from SAMHD1 restriction in primary myeloid cells.

scholarly journals HIV-1 Mutants that Escape the Cytotoxic T-Lymphocytes are Defective in Viral DNA Integration

2021 ◽  
Author(s):  
Muthukumar Balasubramaniam ◽  
Santosh Thapa ◽  
Benem-Orom Davids ◽  
Alex Bryer ◽  
Chaoyi Xu ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Cytotoxic T Lymphocytes ◽  
Human Leukocyte ◽  
Virus Infectivity ◽  
Viral Dna ◽  
Ctl Response ◽  
Dna Integration ◽  
Viral Dna Integration ◽  
Hiv 1 ◽  
Selection Of

ABSTRACTHIV-1 replication is durably controlled in certain untreated HIV-1-infected individuals expressing particular human leukocyte antigens (HLA). These HLAs tag infected cells for elimination by presenting specific viral epitopes to CD8+ cytotoxic T-lymphocytes (CTL). In individuals expressing HLA-B27, CTLs primarily target the capsid protein (CA)-derived KK10 epitope. Selection of CA mutation R264K helps HIV-1 escape the CTL response but severely diminishes virus infectivity. Here we report that the R264K mutation-associated infectivity defect arises primarily from impaired viral DNA integration. Strikingly, selection of the compensatory CA mutation S173A or depletion of host cyclophilin A largely rescues the R264K-associated integration and infectivity defects. Collectively, our study reveals novel mechanistic insights into the fitness defect incurred by an HIV-1 variant escaping a CA-directed CTL response.

scholarly journals Binding to DCAF1 distinguishes TASOR and SAMHD1 degradation by HIV-2 Vpx

2021 ◽  
Author(s):  
Michaël M Martin ◽  
Roy Matkovic ◽  
Pauline Larrous ◽  
Marina Morel ◽  
Angélique Lasserre ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Restriction Factors ◽  
Viral Dna ◽  
Host Restriction ◽  
Viral Expression ◽  
Host Restriction Factors ◽  
Human Immunodeficiency Viruses ◽  
Hiv 1

Human Immunodeficiency viruses type 1 and 2 (HIV-1 and HIV-2) succeed to evade host immune defenses by using their viral auxiliary proteins to antagonize host restriction factors. HIV-2/SIVsmm Vpx is known for degrading SAMHD1, a factor impeding the reverse transcription. More recently, Vpx was also shown to counteract HUSH, a complex constituted of TASOR, MPP8 and periphilin, which blocks viral expression from the integrated viral DNA. In a classical ubiquitin ligase hijacking model, Vpx bridges the DCAF1 ubiquitin ligase substrate adaptor to SAMHD1, for subsequent ubiquitination and degradation. Here, we investigated whether the same mechanism is at stake for Vpx-mediated HUSH degradation. While we confirm that Vpx bridges SAMHD1 to DCAF1, we show that TASOR can interact with DCAF1 in the absence of Vpx. Nonetheless, this association was stabilized in the presence of Vpx, suggesting the existence of a ternary complex. The N-terminal PARP-like domain of TASOR is involved in DCAF1 binding, but not in Vpx binding. We also characterized a series of HIV-2 Vpx point mutants impaired in TASOR degradation, while still degrading SAMHD1. Vpx mutants ability to degrade TASOR correlated with their capacity to enhance HIV-1 minigenome expression as expected. Strikingly, several Vpx mutants impaired for TASOR degradation, but not for SAMHD1 degradation, had a reduced binding affinity for DCAF1, but not for TASOR. In macrophages, Vpx R34A-R42A and Vpx R42A-Q47A-V48A, strongly impaired in DCAF1, but not in TASOR binding, could not degrade TASOR, while being efficient in degrading SAMHD1. Altogether, our results highlight the central role of a robust Vpx-DCAF1 association to trigger TASOR degradation. We then propose a model in which Vpx interacts with both TASOR and DCAF1 to stabilize a TASOR-DCAF1 complex. Furthermore, our work identifies Vpx mutants enabling the study of HUSH restriction independently from SAMHD1 restriction in primary myeloid cells.

scholarly journals Contribution of Host Nucleoporin 62 in HIV-1 Integrase Chromatin Association and Viral DNA Integration

2012 ◽  
Vol 287 (13) ◽  
pp. 10544-10555 ◽  
Author(s):  
Zhujun Ao ◽  
Kallesh Danappa Jayappa ◽  
Binchen Wang ◽  
Yingfeng Zheng ◽  
Xiaoxia Wang ◽  
...  
Keyword(s):  
Viral Dna ◽  
Dna Integration ◽  
Viral Dna Integration ◽  
Hiv 1

scholarly journals Capsid-CPSF6 Interaction Licenses Nuclear HIV-1 Trafficking to Sites of Viral DNA Integration

2018 ◽  
Vol 24 (3) ◽  
pp. 392-404.e8 ◽  
Author(s):  
Vasudevan Achuthan ◽  
Jill M. Perreira ◽  
Gregory A. Sowd ◽  
Maritza Puray-Chavez ◽  
William M. McDougall ◽  
...  
Keyword(s):  
Viral Dna ◽  
Dna Integration ◽  
Viral Dna Integration ◽  
Hiv 1

scholarly journals Transcriptional Coactivator LEDGF/p75 Modulates Human Immunodeficiency Virus Type 1 Integrase-Mediated Concerted Integration

2007 ◽  
Vol 81 (8) ◽  
pp. 3969-3979 ◽  
Author(s):  
Krishan K. Pandey ◽  
Sapna Sinha ◽  
Duane P. Grandgenett
Keyword(s):  
Human Immunodeficiency Virus ◽  
Transcriptional Coactivator ◽  
Viral Dna ◽  
Dna Integration ◽  
Molar Ratios ◽  
Immunodeficiency Virus ◽  
Synaptic Complexes ◽  
Viral Dna Integration ◽  
Hiv 1

ABSTRACT Human transcriptional coactivator p75/lens epithelium-derived growth factor (LEDGF) binds human immunodeficiency virus type 1 (HIV-1) integrase (IN). We studied the effects of LEDGF on the assembly and activity of HIV-1 synaptic complexes, which, upon association with a target, mediate concerted integration of viral DNA substrates in vitro. We found that while augmenting single-ended viral DNA integration into target DNA, the host factor was able to either stimulate or abrogate concerted integration in a concentration-dependent manner. LEDGF modestly stimulated (two- to threefold) concerted integration at low molar ratios to IN (<1). The modest stimulation was independent of solution conditions and several different viral DNA substrates. In solution, concerted integration was inhibited if the molar ratios of LEDGF to IN were >1, apparently due to the disruption of IN-IN interactions essential for the formation of active synaptic complexes prior to their association with a circular target. The isolated IN binding domain of LEDGF was sufficient to stimulate and inhibit concerted integration, as observed with full-length protein, albeit at lower efficiencies. Our data show that LEDGF differentially affects IN-DNA complexes mediating single-ended viral DNA integration and synaptic complexes mediating concerted integration. Synaptic complexes associated with target, termed strand transfer complexes, are resistant to disruption by high concentrations of LEDGF. The results suggest that LEDGF may influence HIV-1 integration in vivo.

scholarly journals Foamy Viruses, Bet, and APOBEC3 Restriction

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Ananda Ayyappan Jaguva Vasudevan ◽  
Daniel Becker ◽  
Tom Luedde ◽  
Holger Gohlke ◽  
Carsten Münk
Keyword(s):  
Current Knowledge ◽  
Regulatory Protein ◽  
Host Population ◽  
Life Cycles ◽  
Restriction Factors ◽  
Host Restriction ◽  
Open Questions ◽  
Foamy Viruses ◽  
Natural Hosts ◽  
Hiv 1

Non-human primates (NHP) are an important source of viruses that can spillover to humans and, after adaptation, spread through the host population. Whereas HIV-1 and HTLV-1 emerged as retroviral pathogens in humans, a unique class of retroviruses called foamy viruses (FV) with zoonotic potential are occasionally detected in bushmeat hunters or zookeepers. Various FVs are endemic in numerous mammalian natural hosts, such as primates, felines, bovines, and equines, and other animals, but not in humans. They are apathogenic, and significant differences exist between the viral life cycles of FV and other retroviruses. Importantly, FVs replicate in the presence of many well-defined retroviral restriction factors such as TRIM5α, BST2 (Tetherin), MX2, and APOBEC3 (A3). While the interaction of A3s with HIV-1 is well studied, the escape mechanisms of FVs from restriction by A3 is much less explored. Here we review the current knowledge of FV biology, host restriction factors, and FV–host interactions with an emphasis on the consequences of FV regulatory protein Bet binding to A3s and outline crucial open questions for future studies.

Host Restriction Factors and Human Immunodeficiency Virus (HIV-1): A Dynamic Interplay Involving All Phases of the Viral Life Cycle

2018 ◽  
Vol 16 (3) ◽  
pp. 184-207 ◽  
Author(s):  
Vanessa D`Urbano ◽  
Elisa De Crignis ◽  
Maria Carla Re
Keyword(s):  
Mammalian Cells ◽  
Viral Evolution ◽  
Type I ◽  
Restriction Factors ◽  
Host Restriction ◽  
Host Restriction Factors ◽  
Immunodeficiency Virus ◽  
Lentiviral Infection ◽  
Specific Proteins ◽  
Hiv 1

Mammalian cells have evolved several mechanisms to prevent or block lentiviral infection and spread. Among the innate immune mechanisms, the signaling cascade triggered by type I interferon (IFN) plays a pivotal role in limiting the burden of HIV-1. In the presence of IFN, human cells upregulate the expression of a number of genes, referred to as IFN-stimulated genes (ISGs), many of them acting as antiviral restriction factors (RFs). RFs are dominant proteins that target different essential steps of the viral cycle, thereby providing an early line of defense against the virus. The identification and characterization of RFs have provided unique insights into the molecular biology of HIV-1, further revealing the complex host-pathogen interplay that characterizes the infection. The presence of RFs drove viral evolution, forcing the virus to develop specific proteins to counteract their activity. The knowledge of the mechanisms that prevent viral infection and their viral counterparts may offer new insights to improve current antiviral strategies. This review provides an overview of the RFs targeting HIV-1 replication and the mechanisms that regulate their expression as well as their impact on viral replication and the clinical course of the disease.

scholarly journals Functional Mapping of Regions Involved in the Negative Imprinting of Virion Particle Infectivity and in Target Cell Protection by Interferon-Induced Transmembrane Protein 3 against HIV-1

2018 ◽  
Vol 93 (2) ◽  
Author(s):  
Romain Appourchaux ◽  
Mathilde Delpeuch ◽  
Li Zhong ◽  
Julien Burlaud-Gaillard ◽  
Kevin Tartour ◽  
...  
Keyword(s):  
Target Cell ◽  
Transmembrane Protein ◽  
Regulatory Role ◽  
Target Cells ◽  
Restriction Factors ◽  
Cell Protection ◽  
Differential Behavior ◽  
Antiviral Activities ◽  
Divergent Behavior ◽  
Hiv 1

ABSTRACT The interferon-induced transmembrane proteins (IFITMs) are a family of highly related antiviral factors that affect numerous viruses at two steps: in target cells by sequestering incoming viruses in endosomes and in producing cells by leading to the production of virions that package IFITMs and exhibit decreased infectivity. While most studies have focused on the former, little is known about the regulation of the negative imprinting of virion particle infectivity by IFITMs and about its relationship with target cell protection. Using a panel of IFITM3 mutants against HIV-1, we have explored these issues as well as others related to the biology of IFITM3, in particular virion packaging, stability, the relation to CD63/multivesicular bodies (MVBs), the modulation of cholesterol levels, and the relationship between negative imprinting of virions and target cell protection. The results that we have obtained exclude a role for cholesterol and indicate that CD63 accumulation does not directly relate to an antiviral behavior. We have defined regions that modulate the two antiviral properties of IFITM3 as well as novel domains that modulate protein stability and that, in so doing, influence the extent of its packaging into virions. The results that we have obtained, however, indicate that, even in the context of an IFITM-susceptible virus, IFITM3 packaging is not sufficient for negative imprinting. Finally, while most mutations concomitantly affect target cell protection and negative imprinting, a region in the C-terminal domain (CTD) exhibits a differential behavior, potentially highlighting the regulatory role that this domain may play in the two antiviral activities of IFITM3. IMPORTANCE IFITM proteins have been associated with the sequestration of incoming virions in endosomes (target cell protection) and with the production of virion particles that incorporate IFITMs and exhibit decreased infectivity (negative imprinting of virion infectivity). How the latter is regulated and whether these two antiviral properties are related remain unknown. By examining the behavior of a large panel of IFITM3 mutants against HIV-1, we determined that IFITM3 mutants are essentially packaged into virions proportionally to their intracellular levels of expression. However, even in the context of an IFITM-susceptible virus, IFITM3 packaging is not sufficient for the antiviral effects. Most mutations were found to concomitantly affect both antiviral properties of IFITM3, but one CTD mutant exhibited a divergent behavior, possibly highlighting a novel regulatory role for this domain. These findings thus advance our comprehension of how this class of broad antiviral restriction factors acts.

Sign in / Sign up

Export Citation Format

Share Document