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Herrmann D, Meng S, Yang H, Mansky LM, Saad JS. The Assembly of HTLV-1-How Does It Differ from HIV-1? Viruses 2024; 16:1528. [PMID: 39459862 PMCID: PMC11512237 DOI: 10.3390/v16101528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2024] [Revised: 09/21/2024] [Accepted: 09/25/2024] [Indexed: 10/28/2024] Open
Abstract
Retroviral assembly is a highly coordinated step in the replication cycle. The process is initiated when the newly synthesized Gag and Gag-Pol polyproteins are directed to the inner leaflet of the plasma membrane (PM), where they facilitate the budding and release of immature viral particles. Extensive research over the years has provided crucial insights into the molecular determinants of this assembly step. It is established that Gag targeting and binding to the PM is mediated by interactions of the matrix (MA) domain and acidic phospholipids such as phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). This binding event, along with binding to viral RNA, initiates oligomerization of Gag on the PM, a process mediated by the capsid (CA) domain. Much of the previous studies have focused on human immunodeficiency virus type 1 (HIV-1). Although the general steps of retroviral replication are consistent across different retroviruses, comparative studies revealed notable differences in the structure and function of viral components. In this review, we present recent findings on the assembly mechanisms of Human T-cell leukemia virus type 1 and highlight key differences from HIV-1, focusing particularly on the molecular determinants of Gag-PM interactions and CA assembly.
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Affiliation(s)
- Dominik Herrmann
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
| | - Shuyu Meng
- Institute for Molecular Virology, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA; (S.M.); (H.Y.); (L.M.M.)
- Molecular Pharmacology and Therapeutics Graduate Program, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA; (S.M.); (H.Y.); (L.M.M.)
| | - Louis M. Mansky
- Institute for Molecular Virology, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA; (S.M.); (H.Y.); (L.M.M.)
- Molecular Pharmacology and Therapeutics Graduate Program, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA
- Department of Diagnostic and Biological Sciences, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA
- Masonic Cancer Center, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota–Twin Cities, Minneapolis, MN 55455, USA
| | - Jamil S. Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
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2
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Muecksch F, Klaus S, Laketa V, Müller B, Kräusslich HG. Probing Gag-Env dynamics at HIV-1 assembly sites using live-cell microscopy. J Virol 2024; 98:e0064924. [PMID: 39136462 PMCID: PMC11406925 DOI: 10.1128/jvi.00649-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 07/02/2024] [Indexed: 09/18/2024] Open
Abstract
Human immunodeficiency virus (HIV)-1 assembly is initiated by Gag binding to the inner leaflet of the plasma membrane (PM). Gag targeting is mediated by its N-terminally myristoylated matrix (MA) domain and PM phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2]. Upon Gag assembly, envelope (Env) glycoproteins are recruited to assembly sites; this process depends on the MA domain of Gag and the Env cytoplasmic tail. To investigate the dynamics of Env recruitment, we applied a chemical dimerizer system to manipulate HIV-1 assembly by reversible PI(4,5)P2 depletion in combination with super resolution and live-cell microscopy. This approach enabled us to control and synchronize HIV-1 assembly and track Env recruitment to individual nascent assembly sites in real time. Single virion tracking revealed that Gag and Env are accumulating at HIV-1 assembly sites with similar kinetics. PI(4,5)P2 depletion prevented Gag PM targeting and Env cluster formation, confirming Gag dependence of Env recruitment. In cells displaying pre-assembled Gag lattices, PI(4,5)P2 depletion resulted in the disintegration of the complete assembly domain, as not only Gag but also Env clusters were rapidly lost from the PM. These results argue for the existence of a Gag-induced and -maintained membrane micro-environment, which attracts Env. Gag cluster dissociation by PI(4,5)P2 depletion apparently disrupts this micro-environment, resulting in the loss of Env from the former assembly domain.IMPORTANCEHuman immunodeficiency virus (HIV)-1 assembles at the plasma membrane of infected cells, resulting in the budding of membrane-enveloped virions. HIV-1 assembly is a complex process initiated by the main structural protein of HIV-1, Gag. Interestingly, HIV-1 incorporates only a few envelope (Env) glycoproteins into budding virions, although large Env accumulations surrounding nascent Gag assemblies are detected at the plasma membrane of HIV-expressing cells. The matrix domain of Gag and the Env cytoplasmatic tail play a role in Env recruitment to HIV-1 assembly sites and its incorporation into nascent virions. However, the regulation of these processes is incompletely understood. By combining a chemical dimerizer system to manipulate HIV-1 assembly with super resolution and live-cell microscopy, our study provides new insights into the interplay between Gag, Env, and host cell membranes during viral assembly and into Env incorporation into HIV-1 virions.
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Affiliation(s)
- Frauke Muecksch
- Department of Infectious Diseases, Virology, Heidelberg University Medical Faculty, Center for Infectious Diseases Research (CIID), Heidelberg, Germany
- Chica and Heinz Schaller (CHS) Research Group, Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany
| | - Severina Klaus
- Department of Infectious Diseases, Virology, Heidelberg University Medical Faculty, Center for Infectious Diseases Research (CIID), Heidelberg, Germany
| | - Vibor Laketa
- Department of Infectious Diseases, Virology, Heidelberg University Medical Faculty, Center for Infectious Diseases Research (CIID), Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, Heidelberg University Medical Faculty, Center for Infectious Diseases Research (CIID), Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Heidelberg University Medical Faculty, Center for Infectious Diseases Research (CIID), Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
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3
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McGraw A, Hillmer G, Choi J, Narayan K, Mehedincu SM, Marquez D, Tibebe H, DeCicco-Skinner KL, Izumi T. Evaluating HIV-1 Infectivity and Virion Maturation across Varied Producer Cells with a Novel FRET-Based Detection and Quantification Assay. Int J Mol Sci 2024; 25:6396. [PMID: 38928103 PMCID: PMC11204348 DOI: 10.3390/ijms25126396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 05/27/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
The maturation of HIV-1 virions is a crucial process in viral replication. Although T-cells are a primary source of virus production, much of our understanding of virion maturation comes from studies using the HEK293T human embryonic kidney cell line. Notably, there is a lack of comparative analyses between T-cells and HEK293T cells in terms of virion maturation efficiency in existing literature. We previously developed an advanced virion visualization system based on the FRET principle, enabling the effective distinction between immature and mature virions via fluorescence microscopy. In this study, we utilized pseudotyped, single-round infectious viruses tagged with FRET labels (HIV-1 Gag-iFRET∆Env) derived from Jurkat (a human T-lymphocyte cell line) and HEK293T cells to evaluate their virion maturation rates. HEK293T-derived virions demonstrated a maturity rate of 81.79%, consistent with other studies and our previous findings. However, virions originating from Jurkat cells demonstrated a significantly reduced maturation rate of 68.67% (p < 0.0001). Correspondingly, viruses produced from Jurkat cells exhibited significantly reduced infectivity compared to those derived from HEK293T cells, with the relative infectivity measured at 65.3%. This finding is consistent with the observed relative maturation rate of viruses produced by Jurkat cells. These findings suggest that initiation of virion maturation directly correlates with viral infectivity. Our observation highlights the dynamic nature of virus-host interactions and their implications for virion production and infectivity.
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Affiliation(s)
- Aidan McGraw
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Grace Hillmer
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Jeongpill Choi
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Kedhar Narayan
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Stefania M. Mehedincu
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Dacia Marquez
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Hasset Tibebe
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Kathleen L. DeCicco-Skinner
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
| | - Taisuke Izumi
- Department of Biology, College of Arts and Sciences, American University, Washington, DC 20016, USA; (A.M.); (G.H.); (J.C.); (K.N.); (S.M.M.); (D.M.); (H.T.); (K.L.D.-S.)
- District of Columbia Center for AIDS Research, Washington, DC 20052, USA
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4
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Sever B, Otsuka M, Fujita M, Ciftci H. A Review of FDA-Approved Anti-HIV-1 Drugs, Anti-Gag Compounds, and Potential Strategies for HIV-1 Eradication. Int J Mol Sci 2024; 25:3659. [PMID: 38612471 PMCID: PMC11012182 DOI: 10.3390/ijms25073659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 03/22/2024] [Accepted: 03/22/2024] [Indexed: 04/14/2024] Open
Abstract
Acquired immunodeficiency syndrome (AIDS) is an enormous global health threat stemming from human immunodeficiency virus (HIV-1) infection. Up to now, the tremendous advances in combination antiretroviral therapy (cART) have shifted HIV-1 infection from a fatal illness into a manageable chronic disorder. However, the presence of latent reservoirs, the multifaceted nature of HIV-1, drug resistance, severe off-target effects, poor adherence, and high cost restrict the efficacy of current cART targeting the distinct stages of the virus life cycle. Therefore, there is an unmet need for the discovery of new therapeutics that not only bypass the limitations of the current therapy but also protect the body's health at the same time. The main goal for complete HIV-1 eradication is purging latently infected cells from patients' bodies. A potential strategy called "lock-in and apoptosis" targets the budding phase of the life cycle of the virus and leads to susceptibility to apoptosis of HIV-1 infected cells for the elimination of HIV-1 reservoirs and, ultimately, for complete eradication. The current work intends to present the main advantages and disadvantages of United States Food and Drug Administration (FDA)-approved anti-HIV-1 drugs as well as plausible strategies for the design and development of more anti-HIV-1 compounds with better potency, favorable pharmacokinetic profiles, and improved safety issues.
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Affiliation(s)
- Belgin Sever
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Anadolu University, Eskisehir 26470, Türkiye;
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
| | - Masami Otsuka
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
- Department of Drug Discovery, Science Farm Ltd., Kumamoto 862-0976, Japan
| | - Mikako Fujita
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
| | - Halilibrahim Ciftci
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto 862-0973, Japan;
- Department of Drug Discovery, Science Farm Ltd., Kumamoto 862-0976, Japan
- Department of Bioengineering Sciences, Izmir Katip Celebi University, Izmir 35620, Türkiye
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5
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Alfadhli A, Romanaggi C, Barklis RL, Barklis E. Second site reversion of HIV-1 envelope protein baseplate mutations maps to the matrix protein. J Virol 2024; 98:e0174223. [PMID: 38193694 PMCID: PMC10878238 DOI: 10.1128/jvi.01742-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024] Open
Abstract
The HIV-1 Envelope (Env) protein cytoplasmic tail (CT) recently has been shown to assemble an unusual trimeric baseplate structure that locates beneath Env ectodomain trimers. Mutations at linchpin residues that help organize the baseplate impair virus replication in restrictive T cell lines but not in permissive cell lines. We have identified and characterized a second site suppressor of these baseplate mutations, located at residue 34 in the viral matrix (MA) protein, that rescues viral replication in restrictive cells. The suppressor mutation was dependent on the CT to exert its activity and did not appear to affect Env protein traffic or fusion functions in restrictive cells. Instead, the suppressor mutation increased Env incorporation into virions 3-fold and virus infectivity in single-round infections 10-fold. We also found that a previously described suppressor of Env-incorporation defects that stabilizes the formation of MA trimers was ineffective at rescuing Env baseplate mutations. Our results support an interpretation in which changes at MA residue 34 induce conformational changes that stabilize MA lattice trimer-trimer interactions and/or direct MA-CT associations.IMPORTANCEHow HIV-1 Env trimers assemble into virus particles remains incompletely understood. In restrictive cells, viral incorporation of Env is dependent on the Env CT and on the MA protein, which assembles lattices composed of hexamers of trimers in immature and mature viruses. Recent evidence indicates that CT assembles trimeric baseplate structures that require membrane-proximal residues to interface with trimeric transmembrane domains and C-terminal helices in the CT. We found that mutations of these membrane-proximal residues impaired replication in restrictive cells. This defect was countered by a MA mutation that does not localize to any obvious interprotein regions but was only inefficiently suppressed by a MA mutation that stabilizes MA trimers and has been shown to suppress other CT-dependent Env defects. Our results suggest that efficient suppression of baseplate mutations involves stabilization of MA inter-trimer contacts and/or direct MA-CT associations. These observations shed new light on how Env assembles into virions.
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Affiliation(s)
- Ayna Alfadhli
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - CeAnn Romanaggi
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - Robin Lid Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
| | - Eric Barklis
- Department of Molecular Microbiology and Immunology, Oregon Health & Sciences University, Portland, Oregon, USA
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6
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Weaver N, Hammonds J, Ding L, Lerner G, Dienger-Stambaugh K, Spearman P. KIF16B Mediates Anterograde Transport and Modulates Lysosomal Degradation of the HIV-1 Envelope Glycoprotein. J Virol 2023; 97:e0025523. [PMID: 37358446 PMCID: PMC10373548 DOI: 10.1128/jvi.00255-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 06/08/2023] [Indexed: 06/27/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) is incorporated into virions at the site of particle assembly on the plasma membrane (PM). The route taken by Env to reach the site of assembly and particle incorporation remains incompletely understood. Following initial delivery to the PM through the secretory pathway, Env is rapidly endocytosed, suggesting that recycling is required for particle incorporation. Endosomes marked by the small GTPase Rab14 have been previously shown to play a role in Env trafficking. Here, we examined the role of KIF16B, the molecular motor protein that directs outward movement of Rab14-dependent cargo, in Env trafficking. Env colocalized extensively with KIF16B+ endosomes at the cellular periphery, while expression of a motor-deficient mutant of KIF16B redistributed Env to a perinuclear location. The half-life of Env labeled at the cell surface was markedly reduced in the absence of KIF16B, while a normal half-life was restored through inhibition of lysosomal degradation. In the absence of KIF16B, Env expression on the surface of cells was reduced, leading to a reduction in Env incorporation into particles and a corresponding reduction in particle infectivity. HIV-1 replication in KIF16B knockout cells was substantially reduced compared to that in wild-type cells. These results indicated that KIF16B regulates an outward sorting step involved in Env trafficking, thereby limiting lysosomal degradation and enhancing particle incorporation. IMPORTANCE The HIV-1 envelope glycoprotein is an essential component of HIV-1 particles. The cellular pathways that contribute to incorporation of envelope into particles are not fully understood. Here, we have identified KIF16B, a motor protein that directs movement from internal compartments toward the plasma membrane, as a host factor that prevents envelope degradation and enhances particle incorporation. This is the first host motor protein identified that contributes to HIV-1 envelope incorporation and replication.
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Affiliation(s)
- Nicholas Weaver
- Immunobiology Division, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
| | - Jason Hammonds
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
| | - Lingmei Ding
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
| | - Grigoriy Lerner
- Immunobiology Division, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
| | - Krista Dienger-Stambaugh
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
| | - Paul Spearman
- Infectious Diseases, Cincinnati Children’s Hospital Medical Center and University of Cincinnati, Cincinnati, Ohio, USA
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7
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Fernandez-de Céspedes MV, Hoffman HK, Carter H, Simons LM, Naing L, Ablan SD, Scheiblin DA, Hultquist JF, van Engelenburg SB, Freed EO. Rab11-FIP1C Is Dispensable for HIV-1 Replication in Primary CD4 + T Cells, but Its Role Is Cell Type Dependent in Immortalized Human T-Cell Lines. J Virol 2022; 96:e0087622. [PMID: 36354340 PMCID: PMC9749476 DOI: 10.1128/jvi.00876-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/11/2022] [Indexed: 11/12/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) contains a long cytoplasmic tail harboring highly conserved motifs that direct Env trafficking and incorporation into virions and promote efficient virus spread. The cellular trafficking factor Rab11a family interacting protein 1C (FIP1C) has been implicated in the directed trafficking of Env to sites of viral assembly. In this study, we confirm that small interfering RNA (siRNA)-mediated depletion of FIP1C in HeLa cells modestly reduces Env incorporation into virions. To determine whether FIP1C is required for Env incorporation and HIV-1 replication in physiologically relevant cells, CRISPR-Cas9 technology was used to knock out the expression of this protein in several human T-cell lines-Jurkat E6.1, SupT1, and H9-and in primary human CD4+ T cells. FIP1C knockout caused modest reductions in Env incorporation in SupT1 cells but did not inhibit virus replication in SupT1 or Jurkat E6.1 T cells. In H9 cells, FIP1C knockout caused a cell density-dependent defect in virus replication. In primary CD4+ T cells, FIP1C knockout had no effect on HIV-1 replication. Furthermore, human T-cell leukemia virus type 1 (HTLV-1)-transformed cell lines that are permissive for HIV-1 replication do not express FIP1C. Mutation of an aromatic motif in the Env cytoplasmic tail (Y795W) implicated in FIP1C-mediated Env incorporation impaired virus replication independently of FIP1C expression in SupT1, Jurkat E6.1, H9, and primary T cells. Together, these results indicate that while FIP1C may contribute to HIV-1 Env incorporation in some contexts, additional and potentially redundant host factors are likely required for Env incorporation and virus dissemination in T cells. IMPORTANCE The incorporation of the HIV-1 envelope (Env) glycoproteins, gp120 and gp41, into virus particles is critical for virus infectivity. gp41 contains a long cytoplasmic tail that has been proposed to interact with host cell factors, including the trafficking factor Rab11a family interacting protein 1C (FIP1C). To investigate the role of FIP1C in relevant cell types-human T-cell lines and primary CD4+ T cells-we used CRISPR-Cas9 to knock out FIP1C expression and examined the effect on HIV-1 Env incorporation and virus replication. We observed that in two of the T-cell lines examined (Jurkat E6.1 and SupT1) and in primary CD4+ T cells, FIP1C knockout did not disrupt HIV-1 replication, whereas FIP1C knockout reduced Env expression and delayed replication in H9 cells. The results indicate that while FIP1C may contribute to Env incorporation in some cell lines, it is not an essential factor for efficient HIV-1 replication in primary CD4+ T cells.
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Affiliation(s)
| | | | - Hannah Carter
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Lacy M. Simons
- Division of Infectious Diseases, Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Lwar Naing
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Sherimay D. Ablan
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - David A. Scheiblin
- Optical Microscopy and Analysis Laboratory, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Judd F. Hultquist
- Division of Infectious Diseases, Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | | | - Eric O. Freed
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
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8
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Viral and Host Factors Regulating HIV-1 Envelope Protein Trafficking and Particle Incorporation. Viruses 2022; 14:v14081729. [PMID: 36016351 PMCID: PMC9415270 DOI: 10.3390/v14081729] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/25/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) is an essential structural component of the virus, serving as the receptor-binding protein and principal neutralizing determinant. Env trimers are incorporated into developing particles at the plasma membrane of infected cells. Incorporation of HIV-1 Env into particles in T cells and macrophages is regulated by the long Env cytoplasmic tail (CT) and the matrix region of Gag. The CT incorporates motifs that interact with cellular factors involved in endosomal trafficking. Env follows an unusual pathway to arrive at the site of particle assembly, first traversing the secretory pathway to the plasma membrane (PM), then undergoing endocytosis, followed by directed sorting to the site of particle assembly on the PM. Many aspects of Env trafficking remain to be defined, including the sequential events that occur following endocytosis, leading to productive recycling and particle incorporation. This review focuses on the host factors and pathways involved in Env trafficking, and discusses leading models of Env incorporation into particles.
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9
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Atomic view of the HIV-1 matrix lattice; implications on virus assembly and envelope incorporation. Proc Natl Acad Sci U S A 2022; 119:e2200794119. [PMID: 35658080 PMCID: PMC9191676 DOI: 10.1073/pnas.2200794119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
SignificanceThe assembly of immature HIV-1 particles is initiated by targeting of the Gag polyproteins to the plasma membrane (PM). Gag binding to the PM is mediated by the N-terminally myristoylated matrix (myrMA) domain. Formation of a Gag lattice on the PM is obligatory for the assembly of immature HIV-1 and envelope (Env) incorporation. The structure of the myrMA lattice presented here provided insights on the molecular factors that stabilize the lattice and hence favor Env incorporation. Our data support a mechanism for Gag binding to the PM during the assembly of immature particles and upon maturation. These findings advance our understanding of a critical step in HIV-1 assembly.
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10
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Sumner C, Ono A. Relationship between HIV-1 Gag Multimerization and Membrane Binding. Viruses 2022; 14:v14030622. [PMID: 35337029 PMCID: PMC8949992 DOI: 10.3390/v14030622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 12/11/2022] Open
Abstract
HIV-1 viral particle assembly occurs specifically at the plasma membrane and is driven primarily by the viral polyprotein Gag. Selective association of Gag with the plasma membrane is a key step in the viral assembly pathway, which is traditionally attributed to the MA domain. MA regulates specific plasma membrane binding through two primary mechanisms including: (1) specific interaction of the MA highly basic region (HBR) with the plasma membrane phospholipid phosphatidylinositol (4,5) bisphosphate [PI(4,5)P2], and (2) tRNA binding to the MA HBR, which prevents Gag association with non-PI(4,5)P2 containing membranes. Gag multimerization, driven by both CA–CA inter-protein interactions and NC-RNA binding, also plays an essential role in viral particle assembly, mediating the establishment and growth of the immature Gag lattice on the plasma membrane. In addition to these functions, the multimerization of HIV-1 Gag has also been demonstrated to enhance its membrane binding activity through the MA domain. This review provides an overview of the mechanisms regulating Gag membrane binding through the MA domain and multimerization through the CA and NC domains, and examines how these two functions are intertwined, allowing for multimerization mediated enhancement of Gag membrane binding.
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11
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Lerner G, Weaver N, Anokhin B, Spearman P. Advances in HIV-1 Assembly. Viruses 2022; 14:v14030478. [PMID: 35336885 PMCID: PMC8952333 DOI: 10.3390/v14030478] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The assembly of HIV-1 particles is a concerted and dynamic process that takes place on the plasma membrane of infected cells. An abundance of recent discoveries has advanced our understanding of the complex sequence of events leading to HIV-1 particle assembly, budding, and release. Structural studies have illuminated key features of assembly and maturation, including the dramatic structural transition that occurs between the immature Gag lattice and the formation of the mature viral capsid core. The critical role of inositol hexakisphosphate (IP6) in the assembly of both the immature and mature Gag lattice has been elucidated. The structural basis for selective packaging of genomic RNA into virions has been revealed. This review will provide an overview of the HIV-1 assembly process, with a focus on recent advances in the field, and will point out areas where questions remain that can benefit from future investigation.
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12
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Bou-Nader C, Muecksch F, Brown JB, Gordon JM, York A, Peng C, Ghirlando R, Summers MF, Bieniasz PD, Zhang J. HIV-1 matrix-tRNA complex structure reveals basis for host control of Gag localization. Cell Host Microbe 2021; 29:1421-1436.e7. [PMID: 34384537 PMCID: PMC8650744 DOI: 10.1016/j.chom.2021.07.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/24/2021] [Accepted: 07/19/2021] [Indexed: 10/20/2022]
Abstract
The HIV-1 virion structural polyprotein, Gag, is directed to particle assembly sites at the plasma membrane by its N-terminal matrix (MA) domain. MA also binds to host tRNAs. To understand the molecular basis of MA-tRNA interaction and its potential function, we present a co-crystal structure of HIV-1 MA-tRNALys3 complex. The structure reveals a specialized group of MA basic and aromatic residues preconfigured to recognize the distinctive structure of the tRNA elbow. Mutational, cross-linking, fluorescence, and NMR analyses show that the crystallographically defined interface drives MA-tRNA binding in solution and living cells. The structure indicates that MA is unlikely to bind tRNA and membrane simultaneously. Accordingly, single-amino-acid substitutions that abolish MA-tRNA binding caused striking redistribution of Gag to the plasma membrane and reduced HIV-1 replication. Thus, HIV-1 exploits host tRNAs to occlude a membrane localization signal and control the subcellular distribution of its major structural protein.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Frauke Muecksch
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Janae B Brown
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Jackson M Gordon
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Ashley York
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Chen Peng
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Michael F Summers
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; Howard Hughes Medical Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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13
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Qu K, Ke Z, Zila V, Anders-Össwein M, Glass B, Mücksch F, Müller R, Schultz C, Müller B, Kräusslich HG, Briggs JAG. Maturation of the matrix and viral membrane of HIV-1. Science 2021; 373:700-704. [PMID: 34353956 DOI: 10.1126/science.abe6821] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 06/24/2021] [Indexed: 12/22/2022]
Abstract
Gag, the primary structural protein of HIV-1, is recruited to the plasma membrane for virus assembly by its matrix (MA) domain. Gag is subsequently cleaved into its component domains, causing structural maturation to repurpose the virion for cell entry. We determined the structure and arrangement of MA within immature and mature HIV-1 through cryo-electron tomography. We found that MA rearranges between two different hexameric lattices upon maturation. In mature HIV-1, a lipid extends out of the membrane to bind with a pocket in MA. Our data suggest that proteolytic maturation of HIV-1 not only assembles the viral capsid surrounding the genome but also repurposes the membrane-bound MA lattice for an entry or postentry function and results in the partial removal of up to 2500 lipids from the viral membrane.
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Affiliation(s)
- Kun Qu
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany
| | - Zunlong Ke
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK
| | - Vojtech Zila
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Maria Anders-Össwein
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Bärbel Glass
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Frauke Mücksch
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Rainer Müller
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Carsten Schultz
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | - Barbara Müller
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg, Germany
| | - John A G Briggs
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany. .,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany
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14
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Eastep GN, Ghanam RH, Green TJ, Saad JS. Structural characterization of HIV-1 matrix mutants implicated in envelope incorporation. J Biol Chem 2021; 296:100321. [PMID: 33485964 PMCID: PMC7952133 DOI: 10.1016/j.jbc.2021.100321] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/05/2021] [Accepted: 01/20/2021] [Indexed: 11/28/2022] Open
Abstract
During the late phase of HIV-1 infection, viral Gag polyproteins are targeted to the plasma membrane (PM) for assembly. Gag localization at the PM is a prerequisite for the incorporation of the envelope protein (Env) into budding particles. Gag assembly and Env incorporation are mediated by the N-terminal myristoylated matrix (MA) domain of Gag. Nonconservative mutations in the trimer interface of MA (A45E, T70R, and L75G) were found to impair Env incorporation and infectivity, leading to the hypothesis that MA trimerization is an obligatory step for Env incorporation. Conversely, Env incorporation can be rescued by a compensatory mutation in the MA trimer interface (Q63R). The impact of these MA mutations on the structure and trimerization properties of MA is not known. In this study, we employed NMR spectroscopy, X-ray crystallography, and sedimentation techniques to characterize the structure and trimerization properties of HIV-1 MA A45E, Q63R, T70R, and L75G mutant proteins. NMR data revealed that these point mutations did not alter the overall structure and folding of MA but caused minor structural perturbations in the trimer interface. Analytical ultracentrifugation data indicated that mutations had a minimal effect on the MA monomer–trimer equilibrium. The high-resolution X-ray structure of the unmyristoylated MA Q63R protein revealed hydrogen bonding between the side chains of adjacent Arg-63 and Ser-67 on neighboring MA molecules, providing the first structural evidence for an additional intermolecular interaction in the trimer interface. These findings advance our knowledge of the interplay of MA trimerization and Env incorporation into HIV-1 particles.
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Affiliation(s)
- Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Todd J Green
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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15
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Dual Pathways of Human Immunodeficiency Virus Type 1 Envelope Glycoprotein Trafficking Modulate the Selective Exclusion of Uncleaved Oligomers from Virions. J Virol 2021; 95:JVI.01369-20. [PMID: 33148792 DOI: 10.1128/jvi.01369-20] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/24/2020] [Indexed: 12/14/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer is transported through the secretory pathway to the infected cell surface and onto virion particles. In the Golgi, the gp160 Env precursor is modified by complex sugars and proteolytically cleaved to produce the mature functional Env trimer, which resists antibody neutralization. We observed mostly uncleaved gp160 and smaller amounts of cleaved gp120 and gp41 Envs on the surface of HIV-1-infected or Env-expressing cells; however, cleaved Envs were relatively enriched in virions and virus-like particles (VLPs). This relative enrichment of cleaved Env in VLPs was observed for wild-type Envs, for Envs lacking the cytoplasmic tail, and for CD4-independent, conformationally flexible Envs. On the cell surface, we identified three distinct populations of Envs: (i) the cleaved Env was transported through the Golgi, was modified by complex glycans, formed trimers that cross-linked efficiently, and was recognized by broadly neutralizing antibodies; (ii) a small fraction of Env modified by complex carbohydrates escaped cleavage in the Golgi; and (iii) the larger population of uncleaved Env lacked complex carbohydrates, cross-linked into diverse oligomeric forms, and was recognized by poorly neutralizing antibodies. This last group of more "open" Env oligomers reached the cell surface in the presence of brefeldin A, apparently bypassing the Golgi apparatus. Relative to Envs transported through the Golgi, these uncleaved Envs were counterselected for virion incorporation. By employing two pathways for Env transport to the surface of infected cells, HIV-1 can misdirect host antibody responses toward conformationally flexible, uncleaved Env without compromising virus infectivity.IMPORTANCE The envelope glycoprotein (Env) trimers on the surface of human immunodeficiency virus type 1 (HIV-1) mediate the entry of the virus into host cells and serve as targets for neutralizing antibodies. The cleaved, functional Env is incorporated into virus particles from the surface of the infected cell. We found that an uncleaved form of Env is transported to the cell surface by an unconventional route, but this nonfunctional Env is mostly excluded from the virus. Thus, only one of the pathways by which Env is transported to the surface of infected cells results in efficient incorporation into virus particles, potentially allowing the uncleaved Env to act as a decoy to the host immune system without compromising virus infectivity.
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16
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Elucidating the Basis for Permissivity of the MT-4 T-Cell Line to Replication of an HIV-1 Mutant Lacking the gp41 Cytoplasmic Tail. J Virol 2020; 94:JVI.01334-20. [PMID: 32938764 DOI: 10.1128/jvi.01334-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/07/2020] [Indexed: 12/11/2022] Open
Abstract
HIV-1 encodes an envelope glycoprotein (Env) that contains a long cytoplasmic tail (CT) harboring trafficking motifs implicated in Env incorporation into virus particles and viral transmission. In most physiologically relevant cell types, the gp41 CT is required for HIV-1 replication, but in the MT-4 T-cell line the gp41 CT is not required for a spreading infection. To help elucidate the role of the gp41 CT in HIV-1 transmission, in this study, we investigated the viral and cellular factors that contribute to the permissivity of MT-4 cells to gp41 CT truncation. We found that the kinetics of HIV-1 production and virus release are faster in MT-4 than in the other T-cell lines tested, but MT-4 cells express equivalent amounts of HIV-1 proteins on a per-cell basis relative to cells not permissive to CT truncation. MT-4 cells express higher levels of plasma-membrane-associated Env than nonpermissive cells, and Env internalization from the plasma membrane is less efficient than that from another T-cell line, SupT1. Paradoxically, despite the high levels of Env on the surface of MT-4 cells, 2-fold less Env is incorporated into virus particles produced from MT-4 than SupT1 cells. Contact-dependent transmission between cocultured 293T and MT-4 cells is higher than in cocultures of 293T with most other T-cell lines tested, indicating that MT-4 cells are highly susceptible to cell-to-cell infection. These data help to clarify the long-standing question of how MT-4 cells overcome the requirement for the HIV-1 gp41 CT and support a role for gp41 CT-dependent trafficking in Env incorporation and cell-to-cell transmission in physiologically relevant cell lines.IMPORTANCE The HIV-1 Env cytoplasmic tail (CT) is required for efficient Env incorporation into nascent particles and viral transmission in primary CD4+ T cells. The MT-4 T-cell line has been reported to support multiple rounds of infection of HIV-1 encoding a gp41 CT truncation. Uncovering the underlying mechanism of MT-4 T-cell line permissivity to gp41 CT truncation would provide key insights into the role of the gp41 CT in HIV-1 transmission. This study reveals that multiple factors contribute to the unique ability of a gp41 CT truncation mutant to spread in cultures of MT-4 cells. The lack of a requirement for the gp41 CT in MT-4 cells is associated with the combined effects of rapid HIV-1 protein production, high levels of cell-surface Env expression, and increased susceptibility to cell-to-cell transmission compared to nonpermissive cells.
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17
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Datir R, Kemp S, El Bouzidi K, Mlchocova P, Goldstein R, Breuer J, Towers GJ, Jolly C, Quiñones-Mateu ME, Dakum PS, Ndembi N, Gupta RK. In Vivo Emergence of a Novel Protease Inhibitor Resistance Signature in HIV-1 Matrix. mBio 2020; 11:e02036-20. [PMID: 33144375 PMCID: PMC7642677 DOI: 10.1128/mbio.02036-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 09/21/2020] [Indexed: 12/16/2022] Open
Abstract
Protease inhibitors (PIs) are the second- and last-line therapy for the majority of HIV-infected patients worldwide. Only around 20% of individuals who fail PI regimens develop major resistance mutations in protease. We sought to explore the role of mutations in gag-pro genotypic and phenotypic changes in viruses from six Nigerian patients who failed PI-based regimens without known drug resistance-associated protease mutations in order to identify novel determinants of PI resistance. Target enrichment and next-generation sequencing (NGS) with the Illumina MiSeq system were followed by haplotype reconstruction. Full-length Gag-protease gene regions were amplified from baseline (pre-PI) and virologic failure (VF) samples, sequenced, and used to construct gag-pro-pseudotyped viruses. Phylogenetic analysis was performed using maximum-likelihood methods. Susceptibility to lopinavir (LPV) and darunavir (DRV) was measured using a single-cycle replication assay. Western blotting was used to analyze Gag cleavage. In one of six participants (subtype CRF02_AG), we found 4-fold-lower LPV susceptibility in viral clones during failure of second-line treatment. A combination of four mutations (S126del, H127del, T122A, and G123E) in the p17 matrix of baseline virus generated a similar 4-fold decrease in susceptibility to LPV but not darunavir. These four amino acid changes were also able to confer LPV resistance to a subtype B Gag-protease backbone. Western blotting demonstrated significant Gag cleavage differences between sensitive and resistant isolates in the presence of drug. Resistant viruses had around 2-fold-lower infectivity than sensitive clones in the absence of drug. NGS combined with haplotype reconstruction revealed that resistant, less fit clones emerged from a minority population at baseline and thereafter persisted alongside sensitive fitter viruses. We used a multipronged genotypic and phenotypic approach to document emergence and temporal dynamics of a novel protease inhibitor resistance signature in HIV-1 matrix, revealing the interplay between Gag-associated resistance and fitness.
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Affiliation(s)
| | - Steven Kemp
- University College London, London, United Kingdom
| | | | - Petra Mlchocova
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | | | - Judy Breuer
- University College London, London, United Kingdom
| | | | - Clare Jolly
- University College London, London, United Kingdom
| | | | - Patrick S Dakum
- Institute for Human Virology, Abuja, Nigeria
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Nicaise Ndembi
- Institute for Human Virology, Abuja, Nigeria
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Ravindra K Gupta
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Africa Health Research Institute, Durban, South Africa
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18
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Boyd PS, Brown JB, Brown JD, Catazaro J, Chaudry I, Ding P, Dong X, Marchant J, O’Hern CT, Singh K, Swanson C, Summers MF, Yasin S. NMR Studies of Retroviral Genome Packaging. Viruses 2020; 12:v12101115. [PMID: 33008123 PMCID: PMC7599994 DOI: 10.3390/v12101115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/18/2020] [Accepted: 09/26/2020] [Indexed: 12/03/2022] Open
Abstract
Nearly all retroviruses selectively package two copies of their unspliced RNA genomes from a cellular milieu that contains a substantial excess of non-viral and spliced viral RNAs. Over the past four decades, combinations of genetic experiments, phylogenetic analyses, nucleotide accessibility mapping, in silico RNA structure predictions, and biophysical experiments were employed to understand how retroviral genomes are selected for packaging. Genetic studies provided early clues regarding the protein and RNA elements required for packaging, and nucleotide accessibility mapping experiments provided insights into the secondary structures of functionally important elements in the genome. Three-dimensional structural determinants of packaging were primarily derived by nuclear magnetic resonance (NMR) spectroscopy. A key advantage of NMR, relative to other methods for determining biomolecular structure (such as X-ray crystallography), is that it is well suited for studies of conformationally dynamic and heterogeneous systems—a hallmark of the retrovirus packaging machinery. Here, we review advances in understanding of the structures, dynamics, and interactions of the proteins and RNA elements involved in retroviral genome selection and packaging that are facilitated by NMR.
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19
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Sengupta P, Lippincott-Schwartz J. Revisiting Membrane Microdomains and Phase Separation: A Viral Perspective. Viruses 2020; 12:v12070745. [PMID: 32664429 PMCID: PMC7412473 DOI: 10.3390/v12070745] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/29/2020] [Accepted: 07/07/2020] [Indexed: 12/11/2022] Open
Abstract
Retroviruses selectively incorporate a specific subset of host cell proteins and lipids into their outer membrane when they bud out from the host plasma membrane. This specialized viral membrane composition is critical for both viral survivability and infectivity. Here, we review recent findings from live cell imaging of single virus assembly demonstrating that proteins and lipids sort into the HIV retroviral membrane by a mechanism of lipid-based phase partitioning. The findings showed that multimerizing HIV Gag at the assembly site creates a liquid-ordered lipid phase enriched in cholesterol and sphingolipids. Proteins with affinity for this specialized lipid environment partition into it, resulting in the selective incorporation of proteins into the nascent viral membrane. Building on this and other work in the field, we propose a model describing how HIV Gag induces phase separation of the viral assembly site through a mechanism involving transbilayer coupling of lipid acyl chains and membrane curvature changes. Similar phase-partitioning pathways in response to multimerizing structural proteins likely help sort proteins into the membranes of other budding structures within cells.
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20
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Brown JB, Summers HR, Brown LA, Marchant J, Canova PN, O'Hern CT, Abbott ST, Nyaunu C, Maxwell S, Johnson T, Moser MB, Ablan SD, Carter H, Freed EO, Summers MF. Structural and Mechanistic Studies of the Rare Myristoylation Signal of the Feline Immunodeficiency Virus. J Mol Biol 2020; 432:4076-4091. [PMID: 32442659 PMCID: PMC7316625 DOI: 10.1016/j.jmb.2020.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/13/2020] [Accepted: 05/14/2020] [Indexed: 10/24/2022]
Abstract
All retroviruses encode a Gag polyprotein containing an N-terminal matrix domain (MA) that anchors Gag to the plasma membrane and recruits envelope glycoproteins to virus assembly sites. Membrane binding by the Gag protein of HIV-1 and most other lentiviruses is dependent on N-terminal myristoylation of MA by host N-myristoyltransferase enzymes (NMTs), which recognize a six-residue "myristoylation signal" with consensus sequence: M1GXXX[ST]. For unknown reasons, the feline immunodeficiency virus (FIV), which infects both domestic and wild cats, encodes a non-consensus myristoylation sequence not utilized by its host or by other mammals (most commonly: M1GNGQG). To explore the evolutionary basis for this sequence, we compared the structure, dynamics, and myristoylation properties of native FIV MA with a mutant protein containing a consensus feline myristoylation motif (MANOS) and examined the impact of MA mutations on virus assembly and ability to support spreading infection. Unexpectedly, myristoylation efficiency of MANOS in Escherichia coli by co-expressed mammalian NMT was reduced by ~70% compared to the wild-type protein. NMR studies revealed that residues of the N-terminal myristoylation signal are fully exposed and mobile in the native protein but partially sequestered in the MANOS chimera, suggesting that the unusual FIV sequence is conserved to promote exposure and efficient myristoylation of the MA N terminus. In contrast, virus assembly studies indicate that the MANOS mutation does not affect virus assembly, but does prevent virus spread, in feline kidney cells. Our findings indicate that residues of the FIV myristoylation sequence play roles in replication beyond NMT recognition and Gag-membrane binding.
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Affiliation(s)
- Janae B Brown
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Holly R Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Lola A Brown
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Jan Marchant
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Paige N Canova
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Colin T O'Hern
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Sophia T Abbott
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Constance Nyaunu
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Simon Maxwell
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Talayah Johnson
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Morgan B Moser
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Sherimay D Ablan
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA
| | - Hannah Carter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute at Fredrick, Fredrick, MD 21702-1201, USA.
| | - Michael F Summers
- Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
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21
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Murphy RE, Saad JS. The Interplay between HIV-1 Gag Binding to the Plasma Membrane and Env Incorporation. Viruses 2020; 12:E548. [PMID: 32429351 PMCID: PMC7291237 DOI: 10.3390/v12050548] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/14/2020] [Accepted: 05/14/2020] [Indexed: 12/21/2022] Open
Abstract
Advancement in drug therapies and patient care have drastically improved the mortality rates of HIV-1 infected individuals. Many of these therapies were developed or improved upon by using structure-based techniques, which underscore the importance of understanding essential mechanisms in the replication cycle of HIV-1 at the structural level. One such process which remains poorly understood is the incorporation of the envelope glycoprotein (Env) into budding virus particles. Assembly of HIV particles is initiated by targeting of the Gag polyproteins to the inner leaflet of the plasma membrane (PM), a process mediated by the N-terminally myristoylated matrix (MA) domain and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). There is strong evidence that formation of the Gag lattice on the PM is a prerequisite for the incorporation of Env into budding particles. It is also suggested that Env incorporation is mediated by an interaction between its cytoplasmic tail (gp41CT) and the MA domain of Gag. In this review, we highlight the latest developments and current efforts to understand the interplay between gp41CT, MA, and the membrane during assembly. Elucidation of the molecular determinants of Gag-Env-membrane interactions may help in the development of new antiviral therapeutic agents that inhibit particle assembly, Env incorporation and ultimately virus production.
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Affiliation(s)
| | - Jamil S. Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
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Dick A, Cocklin S. Recent Advances in HIV-1 Gag Inhibitor Design and Development. Molecules 2020; 25:molecules25071687. [PMID: 32272714 PMCID: PMC7181048 DOI: 10.3390/molecules25071687] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/31/2020] [Accepted: 04/05/2020] [Indexed: 02/06/2023] Open
Abstract
Acquired Immune Deficiency Syndrome (AIDS) treatment with combination antiretroviral therapy (cART) has improved the life quality of many patients since its implementation. However, resistance mutations and the accumulation of severe side effects associated with cART remain enormous challenges that need to be addressed with the continual design and redesign of anti-HIV drugs. In this review, we focus on the importance of the HIV-1 Gag polyprotein as the master coordinator of HIV-1 assembly and maturation and as an emerging drug target. Due to its multiple roles in the HIV-1 life cycle, the individual Gag domains are attractive but also challenging targets for inhibitor design. However, recent encouraging developments in targeting the Gag domains such as the capsid protein with highly potent and potentially long-acting inhibitors, as well as the exploration and successful targeting of challenging HIV-1 proteins such as the matrix protein, have demonstrated the therapeutic viability of this important protein. Such Gag-directed inhibitors have great potential for combating the AIDS pandemic and to be useful tools to dissect HIV-1 biology.
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