scholarly journals MxB sensitivity of HIV-1 is determined by a highly variable and dynamic capsid surface

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Richard J Miles ◽  
Claire Kerridge ◽  
Laura Hilditch ◽  
Christopher Monit ◽  
David A Jacques ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Cytotoxic T Lymphocyte ◽  
Cyclophilin A ◽  
Conformational Flexibility ◽  
Restriction Factors ◽  
Nuclear Entry ◽  
Linear Forms ◽  
Cofactor Binding ◽  
Cofactor Recruitment ◽  
Hiv 1

The type one interferon induced restriction factor Myxovirus resistance B (MxB) restricts HIV-1 nuclear entry evidenced by inhibition of 2-LTR but not linear forms of viral DNA. The HIV-1 capsid is the key determinant of MxB sensitivity and cofactor binding defective HIV-1 capsid mutants P90A (defective for cyclophilin A and Nup358 recruitment) and N74D (defective for CPSF6 recruitment) have reduced dependency on nuclear transport associated cofactors, altered integration targeting preferences and are not restricted by MxB expression. This has suggested that nuclear import mechanism may determine MxB sensitivity. Here we have use genetics to separate HIV-1 nuclear import cofactor dependence from MxB sensitivity. We provide evidence that MxB sensitivity depends on HIV-1 capsid conformation, rather than cofactor recruitment. We show that depleting CPSF6 to change nuclear import pathway does not impact MxB sensitivity, but mutants that recapitulate the effect of Cyclophilin A binding on capsid conformation and dynamics strongly impact MxB sensitivity. We demonstrate that HIV-1 primary isolates have different MxB sensitivities due to cytotoxic T lymphocyte (CTL) selected differences in Gag sequence but similar cofactor dependencies. Overall our work demonstrates a complex relationship between cyclophilin dependence and MxB sensitivity likely driven by CTL escape. We propose that cyclophilin binding provides conformational flexibility to HIV-1 capsid facilitating simultaneous evasion of capsid-targeting restriction factors including TRIM5 as well as MxB.

scholarly journals SUN1 Regulates HIV-1 Nuclear Import in a Manner Dependent on the Interaction between the Viral Capsid and Cellular Cyclophilin A

2018 ◽  
Vol 92 (13) ◽  
pp. e00229-18 ◽  
Author(s):  
Xinlong Luo ◽  
Wei Yang ◽  
Guangxia Gao
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Leukemia Virus ◽  
Cyclophilin A ◽  
Cellular Protein ◽  
Wild Type Virus ◽  
Nuclear Pore ◽  
Nuclear Entry ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) can infect nondividing cells via passing through the nuclear pore complex. The nuclear membrane-imbedded protein SUN2 was recently reported to be involved in the nuclear import of HIV-1. Whether SUN1, which shares many functional similarities with SUN2, is involved in this process remained to be explored. Here we report that overexpression of SUN1 specifically inhibited infection by HIV-1 but not that by simian immunodeficiency virus (SIV) or murine leukemia virus (MLV). Overexpression of SUN1 did not affect reverse transcription but led to reduced accumulation of the 2-long-terminal-repeat (2-LTR) circular DNA and integrated viral DNA, suggesting a block in the process of nuclear import. HIV-1 CA was mapped as a determinant for viral sensitivity to SUN1. Treatment of SUN1-expressing cells with cyclosporine (CsA) significantly reduced the sensitivity of the virus to SUN1, and an HIV-1 mutant containing CA-G89A, which does not interact with cyclophilin A (CypA), was resistant to SUN1 overexpression. Downregulation of endogenous SUN1 inhibited the nuclear entry of the wild-type virus but not that of the G89A mutant. These results indicate that SUN1 participates in the HIV-1 nuclear entry process in a manner dependent on the interaction of CA with CypA.IMPORTANCEHIV-1 infects both dividing and nondividing cells. The viral preintegration complex (PIC) can enter the nucleus through the nuclear pore complex. It has been well known that the viral protein CA plays an important role in determining the pathways by which the PIC enters the nucleus. In addition, the interaction between CA and the cellular protein CypA has been reported to be important in the selection of nuclear entry pathways, though the underlying mechanisms are not very clear. Here we show that both SUN1 overexpression and downregulation inhibited HIV-1 nuclear entry. CA played an important role in determining the sensitivity of the virus to SUN1: the regulatory activity of SUN1 toward HIV-1 relied on the interaction between CA and CypA. These results help to explain how SUN1 is involved in the HIV-1 nuclear entry process.

scholarly journals Binding and Susceptibility to Postentry Restriction Factors in Monkey Cells Are Specified by Distinct Regions of the Human Immunodeficiency Virus Type 1 Capsid

2004 ◽  
Vol 78 (10) ◽  
pp. 5423-5437 ◽  
Author(s):  
Christopher M. Owens ◽  
Byeongwoon Song ◽  
Michel J. Perron ◽  
Peter C. Yang ◽  
Matthew Stremlau ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cyclophilin A ◽  
New World Monkeys ◽  
Restriction Factors ◽  
Factor Binding ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT In cells of Old World and some New World monkeys, dominant factors restrict human immunodeficiency virus type 1 (HIV-1) infections after virus entry. The simian immunodeficiency virus SIVmac is less susceptible to these restrictions, a property that is determined largely by the viral capsid protein. For this study, we altered exposed amino acid residues on the surface of the HIV-1 capsid, changing them to the corresponding residues found on the SIVmac capsid. We identified two distinct pathways of escape from early, postentry restriction in monkey cells. One set of mutants that were altered near the base of the cyclophilin A-binding loop of the N-terminal capsid domain or in the interdomain linker exhibited a decreased ability to bind the restricting factor(s). Consistent with the location of this putative factor-binding site, cyclophilin A and the restricting factor(s) cooperated to achieve the postentry block. A second set of mutants that were altered in the ridge formed by helices 3 and 6 of the N-terminal capsid domain efficiently bound the restricting factor(s) but were resistant to the consequences of factor binding. These results imply that binding of the simian restricting factor(s) is not sufficient to mediate the postentry block to HIV-1 and that SIVmac capsids escape the block by decreases in both factor binding and susceptibility to the effects of the factor(s).

scholarly journals The V86M mutation in HIV-1 capsid confers resistance to TRIM5α by abrogation of cyclophilin a-dependent restriction and enhancement of viral nuclear import

Retrovirology ◽  
2013 ◽  
Vol 10 (1) ◽  
pp. 25 ◽  
Author(s):  
Maxime Veillette ◽  
Katsiaryna Bichel ◽  
Paulina Pawlica ◽  
Stefan M V Freund ◽  
Mélodie B Plourde ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Cyclophilin A ◽  
Hiv 1

scholarly journals HIV-1 replication complexes accumulate in nuclear speckles and integrate into speckle-associated genomic domains

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ashwanth C. Francis ◽  
Mariana Marin ◽  
Parmit K. Singh ◽  
Vasudevan Achuthan ◽  
Mathew J. Prellberg ◽  
...  
Keyword(s):  
Viral Replication ◽  
Nuclear Import ◽  
Integration Site ◽  
Nuclear Speckles ◽  
Nuclear Entry ◽  
Primary Monocyte ◽  
Integration Sites ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor ◽  
Hiv 1

AbstractThe early steps of HIV-1 infection, such as uncoating, reverse transcription, nuclear import, and transport to integration sites are incompletely understood. Here, we imaged nuclear entry and transport of HIV-1 replication complexes in cell lines, primary monocyte-derived macrophages (MDMs) and CD4+ T cells. We show that viral replication complexes traffic to and accumulate within nuclear speckles and that these steps precede the completion of viral DNA synthesis. HIV-1 transport to nuclear speckles is dependent on the interaction of the capsid proteins with host cleavage and polyadenylation specificity factor 6 (CPSF6), which is also required to stabilize the association of the viral replication complexes with nuclear speckles. Importantly, integration site analyses reveal a strong preference for HIV-1 to integrate into speckle-associated genomic domains. Collectively, our results demonstrate that nuclear speckles provide an architectural basis for nuclear homing of HIV-1 replication complexes and subsequent integration into associated genomic loci.

Cyclophilin A modulates the sensitivity of HIV-1 to host restriction factors

10.1038/nm910 ◽  
2003 ◽  
Vol 9 (9) ◽  
pp. 1138-1143 ◽  
Author(s):  
Greg J Towers ◽  
Theodora Hatziioannou ◽  
Simone Cowan ◽  
Stephen P Goff ◽  
Jeremy Luban ◽  
...  
Keyword(s):  
Cyclophilin A ◽  
Restriction Factors ◽  
Host Restriction ◽  
Host Restriction Factors ◽  
Hiv 1

scholarly journals A DNA-origami nuclear pore mimic reveals nuclear entry mechanisms of HIV-1 capsid

2020 ◽  
Author(s):  
Qi Shen ◽  
Chaoyi Xu ◽  
Sooin Jang ◽  
Qiancheng Xiong ◽  
Swapnil C. Devarkar ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Dna Origami ◽  
Nuclear Pore ◽  
Nuclear Entry ◽  
Cellular Factors ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Human Immunodeficiency Virus 1

SummaryThe capsid of human immunodeficiency virus 1 (HIV-1) plays a pivotal role in viral nuclear import, but the mechanism by which the viral core passages the nuclear pore complex (NPC) is poorly understood. Here, we use DNA-origami mimics of the NPC, termed NuPODs (NucleoPorins Organized by DNA), to reveal the mechanistic underpinnings of HIV-1 capsid nuclear entry. We found that trimeric interface formed via three capsid protein hexamers is targeted by a triple-arginine (RRR) motif but not the canonical phenylalanine-glycine (FG) motif of NUP153. As NUP153 is located on the nuclear face of the NPC, this result implies that the assembled capsid must cross the NPC in vivo. This hypothesis is corroborated by our observations of tubular capsid assemblies penetrating through NUP153 NuPODs. NUP153 prefers to bind highly curved capsid assemblies including those found at the tips of viral cores, thereby facilitating capsid insertion into the NPC. Furthermore, a balance of capsid stabilization by NUP153 and deformation by CPSF6, along with other cellular factors, may allow for the intact capsid to pass NPCs of various sizes. The NuPOD system serves as a unique tool for unraveling the previously elusive mechanisms of nuclear import of HIV-1 and other viruses.

scholarly journals From Entry to Egress: Strategic Exploitation of the Cellular Processes by HIV-1

2020 ◽  
Vol 11 ◽  
Author(s):  
Pavitra Ramdas ◽  
Amit Kumar Sahu ◽  
Tarun Mishra ◽  
Vipin Bhardwaj ◽  
Ajit Chande
Keyword(s):  
Life Cycle ◽  
Nuclear Import ◽  
Arms Race ◽  
Surface Proteins ◽  
Restriction Factors ◽  
Host Restriction ◽  
Cellular Processes ◽  
Host Restriction Factors ◽  
Post Entry ◽  
Hiv 1

HIV-1 employs a rich arsenal of viral factors throughout its life cycle and co-opts intracellular trafficking pathways. This exquisitely coordinated process requires precise manipulation of the host microenvironment, most often within defined subcellular compartments. The virus capitalizes on the host by modulating cell-surface proteins and cleverly exploiting nuclear import pathways for post entry events, among other key processes. Successful virus–cell interactions are indeed crucial in determining the extent of infection. By evolving defenses against host restriction factors, while simultaneously exploiting host dependency factors, the life cycle of HIV-1 presents a fascinating montage of an ongoing host–virus arms race. Herein, we provide an overview of how HIV-1 exploits native functions of the host cell and discuss recent findings that fundamentally change our understanding of the post-entry replication events.

scholarly journals Primate TRIM5 proteins form hexagonal nets on HIV-1 capsids

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yen-Li Li ◽  
Viswanathan Chandrasekaran ◽  
Stephen D Carter ◽  
Cora L Woodward ◽  
Devin E Christensen ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Reverse Transcription ◽  
Cyclophilin A ◽  
Restriction Factors ◽  
Viral Capsids ◽  
Ring Domains ◽  
Conformational Plasticity ◽  
Retroviral Infections ◽  
Hiv 1 ◽  
Terminal Domains

TRIM5 proteins are restriction factors that block retroviral infections by binding viral capsids and preventing reverse transcription. Capsid recognition is mediated by C-terminal domains on TRIM5α (SPRY) or TRIMCyp (cyclophilin A), which interact weakly with capsids. Efficient capsid recognition also requires the conserved N-terminal tripartite motifs (TRIM), which mediate oligomerization and create avidity effects. To characterize how TRIM5 proteins recognize viral capsids, we developed methods for isolating native recombinant TRIM5 proteins and purifying stable HIV-1 capsids. Biochemical and EM analyses revealed that TRIM5 proteins assembled into hexagonal nets, both alone and on capsid surfaces. These nets comprised open hexameric rings, with the SPRY domains centered on the edges and the B-box and RING domains at the vertices. Thus, the principles of hexagonal TRIM5 assembly and capsid pattern recognition are conserved across primates, allowing TRIM5 assemblies to maintain the conformational plasticity necessary to recognize divergent and pleomorphic retroviral capsids.

scholarly journals SUN2 Overexpression Deforms Nuclear Shape and Inhibits HIV

2016 ◽  
Vol 90 (8) ◽  
pp. 4199-4214 ◽  
Author(s):  
Daniel A. Donahue ◽  
Sonia Amraoui ◽  
Francesca di Nunzio ◽  
Camille Kieffer ◽  
Françoise Porrot ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Hiv Infection ◽  
Nuclear Membrane ◽  
Cyclophilin A ◽  
Nuclear Lamina ◽  
Nuclear Shape ◽  
Nuclear Entry ◽  
Hiv Inhibition ◽  
Hiv 1 ◽  
Nuclear Membrane Protein

ABSTRACTIn a previous screen of putative interferon-stimulated genes, SUN2 was shown to inhibit HIV-1 infection in an uncharacterized manner. SUN2 is an inner nuclear membrane protein belonging to the linker of nucleoskeleton and cytoskeleton complex. We have analyzed here the role of SUN2 in HIV infection. We report that in contrast to what was initially thought, SUN2 is not induced by type I interferon, and that SUN2 silencing does not modulate HIV infection. However, SUN2 overexpression in cell lines and in primary monocyte-derived dendritic cells inhibits the replication of HIV but not murine leukemia virus or chikungunya virus. We identified HIV-1 and HIV-2 strains that are unaffected by SUN2, suggesting that the effect is specific to particular viral components or cofactors. Intriguingly, SUN2 overexpression induces a multilobular flower-like nuclear shape that does not impact cell viability and is similar to that of cells isolated from patients with HTLV-I-associated adult T-cell leukemia or with progeria. Nuclear shape changes and HIV inhibition both mapped to the nucleoplasmic domain of SUN2 that interacts with the nuclear lamina. This block to HIV replication occurs between reverse transcription and nuclear entry, and passaging experiments selected for a single-amino-acid change in capsid (CA) that leads to resistance to overexpressed SUN2. Furthermore, using chemical inhibition or silencing of cyclophilin A (CypA), as well as CA mutant viruses, we implicated CypA in the SUN2-imposed block to HIV infection. Our results demonstrate that SUN2 overexpression perturbs both nuclear shape and early events of HIV infection.IMPORTANCECells encode proteins that interfere with viral replication, a number of which have been identified in overexpression screens. SUN2 is a nuclear membrane protein that was shown to inhibit HIV infection in such a screen, but how it blocked HIV infection was not known. We show that SUN2 overexpression blocks the infection of certain strains of HIV before nuclear entry. Mutation of the viral capsid protein yielded SUN2-resistant HIV. Additionally, the inhibition of HIV infection by SUN2 involves cyclophilin A, a protein that binds the HIV capsid and directs subsequent steps of infection. We also found that SUN2 overexpression substantially changes the shape of the cell's nucleus, resulting in many flower-like nuclei. Both HIV inhibition and deformation of nuclear shape required the domain of SUN2 that interacts with the nuclear lamina. Our results demonstrate that SUN2 interferes with HIV infection and highlight novel links between nuclear shape and viral infection.

scholarly journals A general model for retroviral capsid pattern recognition by TRIM5 proteins

2017 ◽  
pp. JVI.01563-17 ◽  
Author(s):  
Jonathan M. Wagner ◽  
Devin E. Christensen ◽  
Akash Bhattacharya ◽  
Daria M. Dawidziak ◽  
Marcin D. Roganowicz ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Sequence Similarity ◽  
Hexagonal Lattice ◽  
Cyclophilin A ◽  
Higher Order ◽  
Restriction Factors ◽  
Defense Proteins ◽  
Spry Domain ◽  
Capsid Shell ◽  
Hiv 1

Restriction factors are intrinsic cellular defense proteins that have evolved to block microbial infections. Retroviruses such as HIV-1 are restricted by TRIM5 proteins, which recognize the viral capsid shell that surrounds, organizes, and protects the viral genome. TRIM5α uses a SPRY domain to bind capsids with low intrinsic affinity (KD>1 mM), and therefore requires higher-order assembly into a hexagonal lattice to generate sufficient avidity for productive capsid recognition. TRIMCyp, on the other hand, binds HIV-1 capsids through a cyclophilin A domain, which has a well-defined binding site and higher (KD∼10 μM) affinity for isolated capsid subunits. It has therefore been argued that TRIMCyp proteins may have dispensed with the need for higher-order assembly to function as antiviral factors. Here, we show that, consistent with its high degree of sequence similarity with TRIM5α, the TRIMCyp B-box 2 domain shares the same ability to self-associate and facilitate assembly of a TRIMCyp hexagonal lattice that can wrap about the HIV-1 capsid. We also show that under stringent experimental conditions, TRIMCyp-mediated restriction of HIV-1 is indeed dependent on higher-order assembly. Both forms of TRIM5 therefore use the same mechanism of avidity-driven capsid pattern recognition.IMPORTANCERhesus macaques and owl monkeys are highly resistant to HIV-1 infection due to the activity of TRIM5 restriction factors. The rhesus macaque TRIM5α protein blocks HIV-1 through a mechanism that requires self-assembly of a hexagonal TRIM5α lattice around the invading viral core. Lattice assembly amplifies very weak interactions between the TRIM5α SPRY domain and the HIV-1 capsid. Assembly also promotes dimerization of the TRIM5α RING E3 ligase domain, resulting in synthesis of polyubiquitin chains that mediate downstream steps of restriction. In contrast to rhesus TRIM5α, the owl monkey TRIM5 homolog, TRIMCyp, binds isolated HIV-1 CA subunits more tightly through its cyclophilin A domain, and was therefore thought to act independent of higher-order assembly. Here, we show that TRIMCyp shares the assembly properties of TRIM5α and that both forms of TRIM5 use the same mechanism of hexagonal lattice formation to promote viral recognition and restriction.

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