1
|
Role of the arginine cluster in the disordered domain of Herpes Simplex Virus 1 UL34 for the recruitment of ESCRT-III for viral primary envelopment. J Virol 2021; 96:e0170421. [PMID: 34730397 DOI: 10.1128/jvi.01704-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
During the nuclear export of nascent nucleocapsids of herpesviruses, the nucleocapsids bud through the inner nuclear membrane (INM) by acquiring the INM as a primary envelope (primary envelopment). We recently reported that herpes simplex virus 1 (HSV-1) nuclear egress complex (NEC), which consists of UL34 and UL31, interacts with an ESCRT-III adaptor ALIX and recruits ESCRT-III machinery to the INM for efficient primary envelopment. In this study, we identified a cluster of six arginine residues in the disordered domain of UL34 as a minimal region required for the interaction with ALIX as well as the recruitment of ALIX and an ESCRT-III protein CHMP4B to the INM in HSV-1-infected cells. Mutations in the arginine cluster exhibited phenotypes similar to those with ESCRT-III inhibition reported previously, including the mis-localization of NEC, induction of membranous invagination structures containing enveloped virions, aberrant accumulation of enveloped virions in the invaginations and perinuclear space, and reduction of viral replication. We also showed that the effect of the arginine cluster in UL34 on HSV-1 replication was dependent primarily on ALIX. These results indicated that the arginine cluster in the disordered domain of UL34 was required for the interaction with ALIX and the recruitment of ESCRT-III machinery to the INM to promote primary envelopment. IMPORTANCE Herpesvirus UL34 homologs contain conserved amino-terminal domains that mediate vesicle formation through interactions with UL31 homologs during primary envelopment. UL34 homologs also comprise other domains adjacent to their membrane-anchoring regions, which differ in length, are variable in herpesviruses and do not form distinguished secondary structures. However, the role of these disordered domains in infected cells remains to be elucidated. In this study, we present data suggesting that the arginine cluster in the disordered domain of HSV-1 UL34 mediates the interaction with ALIX, thereby leading to the recruitment of ESCRT-III machinery to the INM for efficient primary envelopment. This is the first study to report the role of the disordered domain of a UL34 homolog in herpesvirus infections.
Collapse
|
2
|
Welker L, Paillart JC, Bernacchi S. Importance of Viral Late Domains in Budding and Release of Enveloped RNA Viruses. Viruses 2021; 13:1559. [PMID: 34452424 PMCID: PMC8402826 DOI: 10.3390/v13081559] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 01/09/2023] Open
Abstract
Late assembly (L) domains are conserved sequences that are necessary for the late steps of viral replication, acting like cellular adaptors to engage the ESCRT membrane fission machinery that promote virion release. These short sequences, whose mutation or deletion produce the accumulation of immature virions at the plasma membrane, were firstly identified within retroviral Gag precursors, and in a further step, also in structural proteins of many other enveloped RNA viruses including arenaviruses, filoviruses, rhabdoviruses, reoviruses, and paramyxoviruses. Three classes of L domains have been identified thus far (PT/SAP, YPXnL/LXXLF, and PPxY), even if it has recently been suggested that other motifs could act as L domains. Here, we summarize the current state of knowledge of the different types of L domains and their cellular partners in the budding events of RNA viruses, with a particular focus on retroviruses.
Collapse
Affiliation(s)
| | | | - Serena Bernacchi
- Architecture et Réactivité de l’ARN, UPR 9002, IBMC, CNRS, Université de Strasbourg, F-67000 Strasbourg, France; (L.W.); (J.-C.P.)
| |
Collapse
|
3
|
Structural Insight into the Interaction of Sendai Virus C Protein with Alix To Stimulate Viral Budding. J Virol 2021; 95:e0081521. [PMID: 34287046 DOI: 10.1128/jvi.00815-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Sendai virus (SeV), belonging to the Respirovirus genus of the family Paramyxoviridae, harbors an accessory protein, named C protein, which facilitates the viral pathogenicity in mice. In addition, the C protein is known to stimulate the budding of virus-like particles through the binding to the host ALG-2 interacting protein X (Alix), a component of the endosomal sorting complexes required for transport (ESCRT) machinery. However, siRNA-mediated gene knockdown studies suggested that neither Alix nor C protein are related to the SeV budding. In the present study, we determined the crystal structure of a complex comprising of the C-terminal half of the C protein (Y3) and the Bro1 domain of Alix at a resolution of 2.2 Å, to investigate the role of the association in the SeV budding. The structure revealed that a novel consensus sequence, LxxW, which is conserved among the Respirovirus C proteins, is important for the Alix-binding. SeV possessing a mutated C protein with a reduced Alix-binding affinity showed impaired virus production, which correlated with the binding affinity. Infectivity analysis showed a 160-fold reduction at 12 h post-infection compared with non-mutated virus, while C protein competes with CHMP4, one subunit of the ESCRT-III complex, on the binding to Alix. Altogether, these results highlight the critical role of C protein in the SeV budding. IMPORTANCE Human parainfluenza virus type I (hPIV1) is a respiratory pathogen affecting in young children, immunocompromised patients, and the elderly, with no available vaccines or antiviral drugs. Sendai virus (SeV), a murine counterpart of hPIV1, has been extensively studied to determine the molecular and biological properties of hPIV1. These viruses possess a multifunctional accessory protein, C protein, which is essential for stimulating the viral reproduction, however, its role in budding remains controversial. In the present study, the crystal structure of the C-terminal half of the SeV C protein associated with the Bro1 domain of Alix, a component of a cell membrane modulating machinery ESCRT, was elucidated. Based on the structure, we designed mutated C proteins with different binding affinity to Alix, and showed that the interaction between C and Alix is vital for the viral budding. These findings provide new insights into the development of a new antiviral drugs against hPIV1.
Collapse
|
4
|
Novel Tsg101 Binding Partners Regulate Viral L Domain Trafficking. Viruses 2021; 13:v13061147. [PMID: 34203832 PMCID: PMC8232796 DOI: 10.3390/v13061147] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/07/2021] [Accepted: 06/09/2021] [Indexed: 02/06/2023] Open
Abstract
Two decades ago, Tsg101, a component of the Endosomal Sorting Complexes Required for Transport (ESCRT) complex 1, was identified as a cellular factor recruited by the human immunodeficiency virus type 1 (HIV-1) to facilitate budding of viral particles assembled at the cell periphery. A highly conserved Pro-(Thr/Ser)-Ala-Pro [P(T/S)AP] motif in the HIV-1 structural polyprotein, Gag, engages a P(T/S)AP-binding pocket in the Tsg101 N-terminal domain. Since the same domain in Tsg101 that houses the pocket was found to bind mono-ubiquitin (Ub) non-covalently, Ub binding was speculated to enhance P(T/S)AP interaction. Within the past five years, we found that the Ub-binding site also accommodates di-Ub, with Lys63-linked di-Ub exhibiting the highest affinity. We also identified small molecules capable of disrupting Ub binding and inhibiting budding. The structural similarity of these molecules, prazoles, to nucleosides prompted testing for nucleic acid binding and led to identification of tRNA as a Tsg101 binding partner. Here, we discuss these recently identified interactions and their contribution to the viral assembly process. These new partners may provide additional insight into the control and function of Tsg101 as well as identify opportunities for anti-viral drug design.
Collapse
|
5
|
Rose KM. When in Need of an ESCRT: The Nature of Virus Assembly Sites Suggests Mechanistic Parallels between Nuclear Virus Egress and Retroviral Budding. Viruses 2021; 13:v13061138. [PMID: 34199191 PMCID: PMC8231873 DOI: 10.3390/v13061138] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/17/2022] Open
Abstract
The proper assembly and dissemination of progeny virions is a fundamental step in virus replication. As a whole, viruses have evolved a myriad of strategies to exploit cellular compartments and mechanisms to ensure a successful round of infection. For enveloped viruses such as retroviruses and herpesviruses, acquisition and incorporation of cellular membrane is an essential process during the formation of infectious viral particles. To do this, these viruses have evolved to hijack the host Endosomal Sorting Complexes Required for Transport (ESCRT-I, -II, and -III) to coordinate the sculpting of cellular membrane at virus assembly and dissemination sites, in seemingly different, yet fundamentally similar ways. For instance, at the plasma membrane, ESCRT-I recruitment is essential for HIV-1 assembly and budding, while it is dispensable for the release of HSV-1. Further, HSV-1 was shown to recruit ESCRT-III for nuclear particle assembly and egress, a process not used by retroviruses during replication. Although the cooption of ESCRTs occurs in two separate subcellular compartments and at two distinct steps for these viral lifecycles, the role fulfilled by ESCRTs at these sites appears to be conserved. This review discusses recent findings that shed some light on the potential parallels between retroviral budding and nuclear egress and proposes a model where HSV-1 nuclear egress may occur through an ESCRT-dependent mechanism.
Collapse
Affiliation(s)
- Kevin M Rose
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, CA 94720, USA
| |
Collapse
|
6
|
Raghav PK, Kalyanaraman K, Kumar D. Human cell receptors: potential drug targets to combat COVID-19. Amino Acids 2021; 53:813-842. [PMID: 33950300 PMCID: PMC8097256 DOI: 10.1007/s00726-021-02991-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 04/21/2021] [Indexed: 01/08/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19). The World Health Organization (WHO) has announced that COVID-19 is a pandemic having a higher spread rate rather than the mortality. Identification of a potential approach or therapy against COVID-19 is still under consideration. Therefore, it is essential to have an insight into SARS-CoV-2, its interacting partner, and domains for an effective treatment. The present study is divided into three main categories, including SARS-CoV-2 prominent receptor and its expression levels, other interacting partners, and their binding domains. The first section focuses primarily on coronaviruses' general aspects (SARS-CoV-2, SARS-CoV, and the Middle East Respiratory Syndrome Coronaviruses (MERS-CoV)) their structures, similarities, and mode of infections. The second section discusses the host receptors which includes the human targets of coronaviruses like dipeptidyl peptidase 4 (DPP4), CD147, CD209L, Angiotensin-Converting Enzyme 2 (ACE2), and other miscellaneous targets (type-II transmembrane serine proteases (TTSPs), furin, trypsin, cathepsins, thermolysin, elastase, phosphatidylinositol 3-phosphate 5-kinase, two-pore segment channel, and epithelium sodium channel C-α subunit). The human cell receptor, ACE2 plays an essential role in the Renin-Angiotensin system (RAS) pathway and COVID-19. Thus, this section also discusses the ACE2 expression and risk of COVID-19 infectivity in various organs and tissues such as the liver, lungs, intestine, heart, and reproductive system in the human body. Absence of ACE2 protein expression in immune cells could be used for limiting the SARS-CoV-2 infection. The third section covers the current available approaches for COVID-19 treatment. Overall, this review focuses on the critical role of human cell receptors involved in coronavirus pathogenesis, which would likely be used in designing target-specific drugs to combat COVID-19.
Collapse
Affiliation(s)
| | - Keerthana Kalyanaraman
- Amity Institute of Biotechnology, Amity University, Sector-125, Noida, Uttar Pradesh, India
| | - Dinesh Kumar
- ICMR-National Institute of Cancer Prevention & Research, Noida, 201301, India.
| |
Collapse
|
7
|
Dicker K, Järvelin AI, Garcia-Moreno M, Castello A. The importance of virion-incorporated cellular RNA-Binding Proteins in viral particle assembly and infectivity. Semin Cell Dev Biol 2021; 111:108-118. [PMID: 32921578 PMCID: PMC7482619 DOI: 10.1016/j.semcdb.2020.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/30/2020] [Accepted: 08/03/2020] [Indexed: 12/14/2022]
Abstract
RNA is a central molecule in RNA virus biology due to its dual function as messenger and genome. However, the small number of proteins encoded by viral genomes is insufficient to enable virus infection. Hence, viruses hijack cellular RNA-binding proteins (RBPs) to aid replication and spread. In this review we discuss the 'knowns' and 'unknowns' regarding the contribution of host RBPs to the formation of viral particles and the initial steps of infection in the newly infected cell. Through comparison of the virion proteomes of ten different human RNA viruses, we confirm that a pool of cellular RBPs are typically incorporated into viral particles. We describe here illustrative examples supporting the important functions of these RBPs in viral particle formation and infectivity and we propose that the role of host RBPs in these steps can be broader than previously anticipated. Understanding how cellular RBPs regulate virus infection can lead to the discovery of novel therapeutic targets against viruses.
Collapse
Affiliation(s)
- Kate Dicker
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Aino I Järvelin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Manuel Garcia-Moreno
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
| | - Alfredo Castello
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK; MRC-University of Glasgow Centre for Virus Research, University of Glasgow, 464 Bearsden Road, Glasgow, G61 1QH, Scotland, UK.
| |
Collapse
|
8
|
The Interplay between ESCRT and Viral Factors in the Enveloped Virus Life Cycle. Viruses 2021; 13:v13020324. [PMID: 33672541 PMCID: PMC7923801 DOI: 10.3390/v13020324] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 02/08/2021] [Accepted: 02/12/2021] [Indexed: 12/13/2022] Open
Abstract
Viruses are obligate parasites that rely on host cellular factors to replicate and spread. The endosomal sorting complexes required for transport (ESCRT) system, which is classically associated with sorting and downgrading surface proteins, is one of the host machineries hijacked by viruses across diverse families. Knowledge gained from research into ESCRT and viruses has, in turn, greatly advanced our understanding of many other cellular functions in which the ESCRT pathway is involved, e.g., cytokinesis. This review highlights the interplay between the ESCRT pathway and the viral factors of enveloped viruses with a special emphasis on retroviruses.
Collapse
|
9
|
Extracellular Vesicles in Viral Pathogenesis: A Case of Dr. Jekyll and Mr. Hyde. Life (Basel) 2021; 11:life11010045. [PMID: 33450847 PMCID: PMC7828316 DOI: 10.3390/life11010045] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/04/2021] [Accepted: 01/11/2021] [Indexed: 02/06/2023] Open
Abstract
Secretion of extracellular vesicles (EVs) is a fundamental property of living cells. EVs are known to transfer biological signals between cells and thus regulate the functional state of recipient cells. Such vesicles mediate the intercellular transport of many biologically active molecules (proteins, nucleic acids, specific lipids) and participate in regulation of key physiological processes. In addition, EVs are involved in the pathogenesis of multiple diseases: infectious, neurodegenerative, and oncological. The current EV classification into microvesicles, apoptotic bodies, and exosomes is based on their size, pathways of cellular biogenesis, and molecular composition. This review is focused on analysis of the role of EVs (mainly exosomes) in the pathogenesis of viral infection. We briefly characterize the biogenesis and molecular composition of various EV types. Then, we consider EV-mediated pro- and anti-viral mechanisms. EV secretion by infected cells can be an important factor of virus spread in target cell populations, or a protective factor limiting viral invasion. The data discussed in this review, on the effect of EV secretion by infected cells on processes in neighboring cells and on immune cells, are of high significance in the search for new therapeutic approaches and for design of new generations of vaccines.
Collapse
|
10
|
Meusser B, Purfuerst B, Luft FC. HIV-1 Gag release from yeast reveals ESCRT interaction with the Gag N-terminal protein region. J Biol Chem 2020; 295:17950-17972. [PMID: 32994219 PMCID: PMC7939435 DOI: 10.1074/jbc.ra120.014710] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/25/2020] [Indexed: 11/30/2022] Open
Abstract
The HIV-1 protein Gag assembles at the plasma membrane and drives virion budding, assisted by the cellular endosomal complex required for transport (ESCRT) proteins. Two ESCRT proteins, TSG101 and ALIX, bind to the Gag C-terminal p6 peptide. TSG101 binding is important for efficient HIV-1 release, but how ESCRTs contribute to the budding process and how their activity is coordinated with Gag assembly is poorly understood. Yeast, allowing genetic manipulation that is not easily available in human cells, has been used to characterize the cellular ESCRT function. Previous work reported Gag budding from yeast spheroplasts, but Gag release was ESCRT-independent. We developed a yeast model for ESCRT-dependent Gag release. We combined yeast genetics and Gag mutational analysis with Gag-ESCRT binding studies and the characterization of Gag-plasma membrane binding and Gag release. With our system, we identified a previously unknown interaction between ESCRT proteins and the Gag N-terminal protein region. Mutations in the Gag-plasma membrane-binding matrix domain that reduced Gag-ESCRT binding increased Gag-plasma membrane binding and Gag release. ESCRT knockout mutants showed that the release enhancement was an ESCRT-dependent effect. Similarly, matrix mutation enhanced Gag release from human HEK293 cells. Release enhancement partly depended on ALIX binding to p6, although binding site mutation did not impair WT Gag release. Accordingly, the relative affinity for matrix compared with p6 in GST-pulldown experiments was higher for ALIX than for TSG101. We suggest that a transient matrix-ESCRT interaction is replaced when Gag binds to the plasma membrane. This step may activate ESCRT proteins and thereby coordinate ESCRT function with virion assembly.
Collapse
Affiliation(s)
- Birgit Meusser
- Charité Medical Faculty, Berlin, Germany; Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | | | - Friedrich C Luft
- Charité Medical Faculty, Berlin, Germany; Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; Experimental and Clinical Research Center, Berlin, Germany.
| |
Collapse
|
11
|
Budding of a Retrovirus: Some Assemblies Required. Viruses 2020; 12:v12101188. [PMID: 33092109 PMCID: PMC7589157 DOI: 10.3390/v12101188] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/23/2020] [Accepted: 06/26/2020] [Indexed: 12/11/2022] Open
Abstract
One of the most important steps in any viral lifecycle is the production of progeny virions. For retroviruses as well as other viruses, this step is a highly organized process that occurs with exquisite spatial and temporal specificity on the cellular plasma membrane. To facilitate this process, retroviruses encode short peptide motifs, or L domains, that hijack host factors to ensure completion of this critical step. One such cellular machinery targeted by viruses is known as the Endosomal Sorting Complex Required for Transport (ESCRTs). Typically responsible for vesicular trafficking within the cell, ESCRTs are co-opted by the retroviral Gag polyprotein to assist in viral particle assembly and release of infectious virions. This review in the Viruses Special Issue “The 11th International Retroviral Nucleocapsid and Assembly Symposium”, details recent findings that shed light on the molecular details of how ESCRTs and the ESCRT adaptor protein ALIX, facilitate retroviral dissemination at sites of viral assembly.
Collapse
|
12
|
How HIV-1 Gag Manipulates Its Host Cell Proteins: A Focus on Interactors of the Nucleocapsid Domain. Viruses 2020; 12:v12080888. [PMID: 32823718 PMCID: PMC7471995 DOI: 10.3390/v12080888] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) polyprotein Gag (Group-specific antigen) plays a central role in controlling the late phase of the viral lifecycle. Considered to be only a scaffolding protein for a long time, the structural protein Gag plays determinate and specific roles in HIV-1 replication. Indeed, via its different domains, Gag orchestrates the specific encapsidation of the genomic RNA, drives the formation of the viral particle by its auto-assembly (multimerization), binds multiple viral proteins, and interacts with a large number of cellular proteins that are needed for its functions from its translation location to the plasma membrane, where newly formed virions are released. Here, we review the interactions between HIV-1 Gag and 66 cellular proteins. Notably, we describe the techniques used to evidence these interactions, the different domains of Gag involved, and the implications of these interactions in the HIV-1 replication cycle. In the final part, we focus on the interactions involving the highly conserved nucleocapsid (NC) domain of Gag and detail the functions of the NC interactants along the viral lifecycle.
Collapse
|
13
|
Alix-Mediated Rescue of Feline Immunodeficiency Virus Budding Differs from That Observed with Human Immunodeficiency Virus. J Virol 2020; 94:JVI.02019-19. [PMID: 32213612 DOI: 10.1128/jvi.02019-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 03/11/2020] [Indexed: 02/06/2023] Open
Abstract
The structural protein Gag is the only viral component required for retroviral budding from infected cells. Each of the three conserved domains-the matrix (MA), capsid (CA), and nucleocapsid (NC) domains-drives different phases of viral particle assembly and egress. Once virus assembly is complete, retroviruses, like most enveloped viruses, utilize host proteins to catalyze membrane fission and to free progeny virions. These proteins are members of the endosomal sorting complex required for transport (ESCRT), a cellular machinery that coats the inside of budding necks to perform membrane-modeling events necessary for particle abscission. The ESCRT is recruited through interactions with PTAP and LYPXnL, two highly conserved sequences named late (L) domains, which bind TSG101 and Alix, respectively. A TSG101-binding L-domain was identified in the p2 region of the feline immunodeficiency virus (FIV) Gag protein. Here, we show that the human protein Alix stimulates the release of virus from FIV-expressing human cells. Furthermore, we demonstrate that the Alix Bro1 domain rescues FIV mutants lacking a functional TSG101-interacting motif, independently of the entire p2 region and of the canonical Alix-binding L-domain(s) in FIV Gag. However, in contrast to the effect on human immunodeficiency virus type 1 (HIV-1), the C377,409S double mutation, which disrupts both CCHC zinc fingers in the NC domain, does not abrogate Alix-mediated virus rescue. These studies provide insight into conserved and divergent mechanisms of lentivirus-host interactions involved in virus budding.IMPORTANCE FIV is a nonprimate lentivirus that infects domestic cats and causes a syndrome that is reminiscent of AIDS in humans. Based on its similarity to HIV with regard to different molecular and biochemical properties, FIV represents an attractive model for the development of strategies to prevent and/or treat HIV infection. Here, we show that the Bro1 domain of the human cellular protein Alix is sufficient to rescue the budding of FIV mutants devoid of canonical L-domains. Furthermore, we demonstrate that the integrity of the CCHC motifs in the Gag NC domain is dispensable for Alix-mediated rescue of virus budding, suggesting the involvement of other regions of the Gag viral protein. Our research is pertinent to the identification of a conserved yet mechanistically divergent ESCRT-mediated lentivirus budding process in general, and to the role of Alix in particular, which underlies the complex viral-cellular network of interactions that promote late steps of the retroviral life cycle.
Collapse
|
14
|
Watanabe SM, Strickland M, Tjandra N, Carter CA. RNA Binding Suppresses Tsg101 Recognition of Ub-Modified Gag and Facilitates Recruitment to the Plasma Membrane. Viruses 2020; 12:v12040447. [PMID: 32326417 PMCID: PMC7232412 DOI: 10.3390/v12040447] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 04/07/2020] [Accepted: 04/10/2020] [Indexed: 01/09/2023] Open
Abstract
The ESCRT-I factor Tsg101 is essential for sorting endocytic cargo and is exploited by viral pathogens to facilitate egress from cells. Both the nucleocapsid (NC) domain and p6 domain in HIV-1 Gag contribute to recruitment of the protein. However, the role of NC is unclear when the P(S/T)AP motif in p6 is intact, as the motif recruits Tsg101 directly. The zinc fingers in NC bind RNA and membrane and are critical for budding. Tsg101 can substitute for the distal ZnF (ZnF2) and rescue budding of a mutant made defective by deletion of this element. Here, we report that the ubiquitin (Ub) E2 variant (UEV) domain in Tsg101 binds tRNA in vitro. We confirmed that Tsg101 can substitute for ZnF2 when provided at the viral assembly site as a chimeric Gag-Tsg101 protein (Gag-ΔZnF2-Tsg101) and rescue budding. The UEV was not required in this context; however, mutation of the RNA binding determinants in UEV prevented Tsg101 recruitment from the cell interior when Gag and Tsg101 were co-expressed. The same Tsg101 mutations increased recognition of Gag-Ub, suggesting that tRNA and Ub compete for binding sites. This study identifies a novel Tsg101 binding partner that may contribute to its function in recognition of Ub-modified cargo.
Collapse
Affiliation(s)
- Susan M. Watanabe
- Department of Microbiology & Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA;
| | - Madeleine Strickland
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Nico Tjandra
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA;
- Correspondence: (N.T.); (C.A.C.); Tel.: +1-631-632-8801 (C.A.C.)
| | - Carol A. Carter
- Department of Microbiology & Immunology, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY 11794-5222, USA;
- Correspondence: (N.T.); (C.A.C.); Tel.: +1-631-632-8801 (C.A.C.)
| |
Collapse
|
15
|
Cervera L, Gòdia F, Tarrés-Freixas F, Aguilar-Gurrieri C, Carrillo J, Blanco J, Gutiérrez-Granados S. Production of HIV-1-based virus-like particles for vaccination: achievements and limits. Appl Microbiol Biotechnol 2019; 103:7367-7384. [DOI: 10.1007/s00253-019-10038-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 12/20/2022]
|
16
|
Larijani MS, Sadat SM, Bolhassani A, Pouriayevali MH, Bahramali G, Ramezani A. In Silico Design and Immunologic Evaluation of HIV-1 p24-Nef Fusion Protein to Approach a Therapeutic Vaccine Candidate. Curr HIV Res 2019; 16:322-337. [PMID: 30605062 PMCID: PMC6446525 DOI: 10.2174/1570162x17666190102151717] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 12/04/2018] [Accepted: 12/27/2018] [Indexed: 01/24/2023]
Abstract
Background: Acquired immune deficiency syndrome (HIV/AIDS) has been a major glob-al health concern for over 38 years. No safe and effective preventive or therapeutic vaccine has been developed although many products have been investigated. Computational methods have facilitated vaccine developments in recent decades. Among HIV-1 proteins, p24 and Nef are two suitable targets to provoke the cellular immune response. However, the fusion form of these two proteins has not been analyzed in silico yet. Objective: This study aimed at the evaluation of possible fusion forms of p24 and Nef in order to achieve a potential therapeutic subunit vaccine against HIV-1. Method: In this study, various computational approaches have been applied to predict the most effec-tive fusion form of p24-Nef including CTL (Cytotoxic T lymphocytes) response, immunogenicity, conservation and population coverage. Moreover, binding to MHC (Major histocompatibility com-plex) molecules was assessed in both human and BALB/c. Results: After analyzing six possible fusion protein forms using AAY linker, we came up with the most practical form of p24 from 80 to 231 and Nef from 120 to 150 regions (according to their refer-ence sequence of HXB2 strain) using an AAY linker, based on their peptides affinity to MHC mole-cules which are located in a conserved region among different virus clades. The selected fusion protein contains seventeen MHC I antigenic epitopes, among them KRWIILGLN, YKRWIILGL, DIAG-TTSTL and FPDWQNYTP are fully conserved between the virus clades. Furthermore, analyzed class I CTL epitopes showed greater affinity binding to HLA-B 57*01, HLA-B*51:01 and HLA-B 27*02 molecules. The population coverage with the rate of >70% coverage in the Persian population supports this truncated form as an appropriate candidate against HIV-I virus. Conclusion: The predicted fusion protein, p24-AAY-Nef in a truncated form with a high rate of T cell epitopes and high conservancy rate among different clades, provides a helpful model for developing a therapeutic vaccine candidate against HIV-1.
Collapse
Affiliation(s)
- Mona Sadat Larijani
- Hepatitis, AIDS and Bloodborne Diseases Department, Pasteur Institute of Iran, Tehran, Iran
| | - Seyed Mehdi Sadat
- Hepatitis, AIDS and Bloodborne Diseases Department, Pasteur Institute of Iran, Tehran, Iran
| | - Azam Bolhassani
- Hepatitis, AIDS and Bloodborne Diseases Department, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Hassan Pouriayevali
- Department of Arboviruses and Viral Hemorrhagic Fevers (National Ref Lab), Pasteur Institute of Iran (IPI) Tehran, Iran
| | - Golnaz Bahramali
- Hepatitis, AIDS and Bloodborne Diseases Department, Pasteur Institute of Iran, Tehran, Iran
| | - Amitis Ramezani
- Hepatitis, AIDS and Bloodborne Diseases Department, Pasteur Institute of Iran, Tehran, Iran
| |
Collapse
|
17
|
Abstract
The p2b domain of Rous sarcoma virus (RSV) Gag and the p6 domain of HIV-1 Gag contain late assembly (L) domains that engage the ESCRT membrane fission machinery and are essential for virus release. We now show that the PPXY-type RSV L domain specifically recruits the BAR domain protein PACSIN2 into virus-like particles (VLP), in addition to the NEDD4-like ubiquitin ligase ITCH and ESCRT pathway components such as TSG101. PACSIN2, which has been implicated in the remodeling of cellular membranes and the actin cytoskeleton, is also recruited by HIV-1 p6 independent of its ability to engage the ESCRT factors TSG101 or ALIX. Moreover, PACSIN2 is robustly recruited by NEDD4-2s, a NEDD4-like ubiquitin ligase capable of rescuing HIV-1 budding defects. The NEDD4-2s-induced incorporation of PACSIN2 into VLP correlated with the formation of Gag-ubiquitin conjugates, indicating that PACSIN2 binds ubiquitin. Although PACSIN2 was not required for a single cycle of HIV-1 replication after infection with cell-free virus, HIV-1 spreading was nevertheless severely impaired in T cell lines and primary human peripheral blood mononuclear cells depleted of PACSIN2. HIV-1 spreading could be restored by reintroduction of wild-type PACSIN2, but not of a SH3 domain mutant unable to interact with the actin polymerization regulators WASP and N-WASP. Overall, our observations indicate that PACSIN2 promotes the cell-to-cell spreading of HIV-1 by connecting Gag to the actin cytoskeleton.
Collapse
|
18
|
PYRE insertion within HIV-1 subtype C p6-Gag functions as an ALIX-dependent late domain. Sci Rep 2018; 8:8917. [PMID: 29891975 PMCID: PMC5995805 DOI: 10.1038/s41598-018-27162-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 05/18/2018] [Indexed: 11/23/2022] Open
Abstract
ALG-2 interacting protein X (ALIX) links HIV-1 Gag to the components of ESCRT-III. HIV-1 engages the ALIX via its nucleocapsid and LYPXnL motif in p6. Overexpression of ALIX corrects the release defect of PTAP deleted HIV-1 via LYPXnL/ALIX pathway. However, HIV-1 subtype C lacks the LYPXnL motif and hence cannot employ LYPXnL/ALIX mechanism. Though the preferential occurrences of PYXE insertion in HIV-1 C p6 is predicted to restore the ALIX binding site there is no functional proof to support these observations. In this study we show that HIV-1 construct with subtype C p6 having PTAP deletion and PYRE insertion (pNL-INp6ΔPTAP/PYRE) could respond to ALIX overexpression. Notably, conserved Phenyl alanine residue (F676) in ALIX was critical for ALIX mediated release of pNL-INp6ΔPTAP/PYRE implying the critical role of this hydrophobic patch in ALIX recruitment. In addition, we show that Nedd4-1 could also correct the release defect of pNL-INp6ΔPTAP/PYRE. Moreover, Nedd4-1 was more robust compared to ALIX in its ability to stimulate the release of pNL-INp6ΔPTAP/PYRE. Replication kinetic data highlights the positive effect of PYRE insertion on virus replication. In summary, our data reveals the functional role of PYRE insertion towards the cooperative mechanism of ALIX/Nedd4-1 in virus release in the absence of PTAP/Tsg101 pathway.
Collapse
|
19
|
El Meshri SE, Boutant E, Mouhand A, Thomas A, Larue V, Richert L, Vivet-Boudou V, Mély Y, Tisné C, Muriaux D, de Rocquigny H. The NC domain of HIV-1 Gag contributes to the interaction of Gag with TSG101. Biochim Biophys Acta Gen Subj 2018; 1862:1421-1431. [PMID: 29571744 DOI: 10.1016/j.bbagen.2018.03.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/20/2018] [Accepted: 03/19/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND HIV-1 Gag polyprotein orchestrates the assembly of viral particles. Its C-terminus consists of the nucleocapsid (NC) domain that interacts with RNA, and the p6 domain containing the PTAP motif that binds the cellular ESCRT factor TSG101 and ALIX. Deletion of the NC domain of Gag (GagNC) results in defective Gag assembly, a decrease in virus production and, thus probably affects recruitment of the ESCRT machinery. To investigate the role of GagNC in this recruitment, we analysed its impact on TSG101 and ALIX localisations and interactions in cells expressing Gag. METHODS Cells expressing mCherry-Gag or derivatives, alone or together with eGFP-TSG101 or eGFP-ALIX, were analysed by confocal microscopy and FLIM-FRET. Chemical shift mapping between TSG101-UEV motif and Gag C-terminus was performed by NMR. RESULTS We show that deletion of NC or of its two zinc fingers decreases the amount of Gag-TSG101 interacting complexes in cells. These findings are supported by NMR data showing chemical shift perturbations in the NC domain in- and outside - of the zinc finger elements upon TSG101 binding. The NMR data further identify a large stretch of amino acids within the p6 domain directly interacting with TSG101. CONCLUSION The NC zinc fingers and p6 domain of Gag participate in the formation of the Gag-TSG101 complex and in its cellular localisation. GENERAL SIGNIFICANCE This study illustrates that the NC and p6 domains cooperate in the interaction with TSG101 during HIV-1 budding. In addition, details on the Gag-TSG101 complex were obtained by combining two high resolution biophysical techniques.
Collapse
Affiliation(s)
- Salah Edin El Meshri
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France
| | - Emmanuel Boutant
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France
| | - Assia Mouhand
- Laboratoire de Cristallographie et RMN biologiques, UMR 8015, CNRS, Université Paris Descartes, 4 avenue de l'Observatoire, 75006 Paris, France; Laboratoire d'Expression génétique microbienne, IBPC, UMR 8261, CNRS, Université Paris Diderot, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Audrey Thomas
- Membrane Domains and Viral Assembly, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, UMR9004, 1919 route de Mende, 34293 Montpellier cedex 5, France
| | - Valéry Larue
- Laboratoire de Cristallographie et RMN biologiques, UMR 8015, CNRS, Université Paris Descartes, 4 avenue de l'Observatoire, 75006 Paris, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France
| | - Valérie Vivet-Boudou
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, IBMC, 15 Rue R. Descartes, 67084 Strasbourg Cedex, France
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France
| | - Carine Tisné
- Laboratoire de Cristallographie et RMN biologiques, UMR 8015, CNRS, Université Paris Descartes, 4 avenue de l'Observatoire, 75006 Paris, France; Laboratoire d'Expression génétique microbienne, IBPC, UMR 8261, CNRS, Université Paris Diderot, 13 rue Pierre et Marie Curie, 75005 Paris, France.
| | - Delphine Muriaux
- Membrane Domains and Viral Assembly, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, UMR9004, 1919 route de Mende, 34293 Montpellier cedex 5, France.
| | - Hugues de Rocquigny
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France; Morphogenèse et Antigénicité du VIH et des Virus des Hépatites, Inserm - U1259 MAVIVH, 10 boulevard Tonnellé - BP 3223, 37032 Tours Cedex 1 -, France.
| |
Collapse
|
20
|
Hadpech S, Nangola S, Chupradit K, Fanhchaksai K, Furnon W, Urvoas A, Valerio-Lepiniec M, Minard P, Boulanger P, Hong SS, Tayapiwatana C. Alpha-helicoidal HEAT-like Repeat Proteins (αRep) Selected as Interactors of HIV-1 Nucleocapsid Negatively Interfere with Viral Genome Packaging and Virus Maturation. Sci Rep 2017; 7:16335. [PMID: 29180782 PMCID: PMC5703948 DOI: 10.1038/s41598-017-16451-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 11/13/2017] [Indexed: 12/21/2022] Open
Abstract
A new generation of artificial proteins, derived from alpha-helicoidal HEAT-like repeat protein scaffolds (αRep), was previously characterized as an effective source of intracellular interfering proteins. In this work, a phage-displayed library of αRep was screened on a region of HIV-1 Gag polyprotein encompassing the C-terminal domain of the capsid, the SP1 linker and the nucleocapsid. This region is known to be essential for the late steps of HIV-1 life cycle, Gag oligomerization, viral genome packaging and the last cleavage step of Gag, leading to mature, infectious virions. Two strong αRep binders were isolated from the screen, αRep4E3 (32 kDa; 7 internal repeats) and αRep9A8 (28 kDa; 6 internal repeats). Their antiviral activity against HIV-1 was evaluated in VLP-producer cells and in human SupT1 cells challenged with HIV-1. Both αRep4E3 and αRep9A8 showed a modest but significant antiviral effects in all bioassays and cell systems tested. They did not prevent the proviral integration reaction, but negatively interfered with late steps of the HIV-1 life cycle: αRep4E3 blocked the viral genome packaging, whereas αRep9A8 altered both virus maturation and genome packaging. Interestingly, SupT1 cells stably expressing αRep9A8 acquired long-term resistance to HIV-1, implying that αRep proteins can act as antiviral restriction-like factors.
Collapse
Affiliation(s)
- Sudarat Hadpech
- Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand.,Center of Biomolecular Therapy and Diagnostic, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand.,Faculty of Pharmaceutical Science, Burapha University, Muang District, Chonburi Province, 20131, Thailand.,University Lyon 1, UMR754-INRA-EPHE, Viral Infections and Comparative Pathology, 50, Avenue Tony Garnier, 69366, Lyon Cedex 07, France
| | - Sawitree Nangola
- Division of Clinical Immunology and Transfusion Sciences, School of Allied Health Sciences, University of Phayao, Phayao, 56000, Thailand
| | - Koollawat Chupradit
- Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand.,Center of Biomolecular Therapy and Diagnostic, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Kanda Fanhchaksai
- Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand.,Center of Biomolecular Therapy and Diagnostic, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Wilhelm Furnon
- University Lyon 1, UMR754-INRA-EPHE, Viral Infections and Comparative Pathology, 50, Avenue Tony Garnier, 69366, Lyon Cedex 07, France
| | - Agathe Urvoas
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Marie Valerio-Lepiniec
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Philippe Minard
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France
| | - Pierre Boulanger
- University Lyon 1, UMR754-INRA-EPHE, Viral Infections and Comparative Pathology, 50, Avenue Tony Garnier, 69366, Lyon Cedex 07, France
| | - Saw-See Hong
- University Lyon 1, UMR754-INRA-EPHE, Viral Infections and Comparative Pathology, 50, Avenue Tony Garnier, 69366, Lyon Cedex 07, France. .,Institut National de la Santé et de la Recherche Médicale, 101, rue de Tolbiac, 75654, Paris Cedex 13, France.
| | - Chatchai Tayapiwatana
- Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand. .,Center of Biomolecular Therapy and Diagnostic, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, 50200, Thailand.
| |
Collapse
|
21
|
Lippincott-Schwartz J, Freed EO, van Engelenburg SB. A Consensus View of ESCRT-Mediated Human Immunodeficiency Virus Type 1 Abscission. Annu Rev Virol 2017; 4:309-325. [PMID: 28715971 DOI: 10.1146/annurev-virology-101416-041840] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The strong dependence of retroviruses, such as human immunodeficiency virus type 1 (HIV-1), on host cell factors is no more apparent than when the endosomal sorting complex required for transport (ESCRT) machinery is purposely disengaged. The resulting potent inhibition of retrovirus release underscores the importance of understanding fundamental structure-function relationships at the ESCRT-HIV-1 interface. Recent studies utilizing advanced imaging technologies have helped clarify these relationships, overcoming hurdles to provide a range of potential models for ESCRT-mediated virus abscission. Here, we discuss these models in the context of prior work detailing ESCRT machinery and the HIV-1 release process. To provide a template for further refinement, we propose a new working model for ESCRT-mediated HIV-1 release that reconciles disparate and seemingly conflicting studies.
Collapse
Affiliation(s)
| | - E O Freed
- The Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, Maryland 21701
| | - S B van Engelenburg
- Department of Biological Sciences, University of Denver, Denver, Colorado 80210;
| |
Collapse
|
22
|
Analysis of the functional compatibility of SIV capsid sequences in the context of the FIV gag precursor. PLoS One 2017; 12:e0177297. [PMID: 28475623 PMCID: PMC5419655 DOI: 10.1371/journal.pone.0177297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 04/25/2017] [Indexed: 02/02/2023] Open
Abstract
The formation of immature lentiviral particles is dependent on the multimerization of the Gag polyprotein at the plasma membrane of the infected cells. One key player in the virus assembly process is the capsid (CA) domain of Gag, which establishes the protein-protein interactions that give rise to the hexagonal lattice of Gag molecules in the immature virion. To gain a better understanding of the functional equivalence between the CA proteins of simian and feline immunodeficiency viruses (SIV and FIV, respectively), we generated a series of chimeric FIV Gag proteins in which the CA-coding region was partially or totally replaced by its SIV counterpart. All the FIV Gag chimeras were found to be assembly-defective; however, all of them are able to interact with wild-type SIV Gag and be recruited into extracellular virus-like particles, regardless of the SIV CA sequences present in the chimeric FIV Gag. The results presented here markedly contrast with our previous findings showing that chimeric SIVs carrying FIV CA-derived sequences are assembly-competent. Overall, our data support the notion that although the SIV and FIV CA proteins share 51% amino acid sequence similarity and exhibit a similar organization, i.e., an N-terminal domain joined by a flexible linker to a C-terminal domain, their functional exchange between these different lentiviruses is strictly dependent on the context of the recipient Gag precursor.
Collapse
|
23
|
Sette P, O'Connor SK, Yerramilli VS, Dussupt V, Nagashima K, Chutiraka K, Lingappa J, Scarlata S, Bouamr F. HIV-1 Nucleocapsid Mimics the Membrane Adaptor Syntenin PDZ to Gain Access to ESCRTs and Promote Virus Budding. Cell Host Microbe 2016; 19:336-48. [PMID: 26962944 DOI: 10.1016/j.chom.2016.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/07/2016] [Accepted: 02/11/2016] [Indexed: 01/09/2023]
Abstract
HIV-1 recruits cellular endosomal sorting complexes required for transport (ESCRTs) to bud virions from the membrane. Disruption of the viral nucleocapsid (NC) domain integrity affects HIV-1 budding. However, the molecular mechanisms of NC's involvement in HIV budding remain unclear. We find that NC mimics the PDZ domains of syntenin, a membrane-binding adaptor involved in cell-to-cell contact/communication, to capture the Bro1 domain of ALIX, which is an ESCRTs recruiting cellular adaptor. NC binds membranes via basic residues in either the distal or proximal zinc fingers, and NC-membrane binding is essential for Bro1 capture and HIV-1 budding. Removal of RNA enhances NC membrane binding, suggesting a dynamic competition between membrane lipids and RNA for the same binding sites in NC. Remarkably, syntenin PDZ can substitute for NC function in HIV-1 budding. Thus, NC mimics syntenin PDZs to function as a membrane-binding adaptor critical for HIV-1 budding at specific microdomains of the membrane.
Collapse
Affiliation(s)
- Paola Sette
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD 20894, USA
| | - Sarah K O'Connor
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD 20894, USA
| | - V Siddartha Yerramilli
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Vincent Dussupt
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD 20894, USA
| | - Kunio Nagashima
- Electron Microscope Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Kasana Chutiraka
- Department of Global Health, University of Washington, Seattle, WA 98102, USA
| | - Jaisri Lingappa
- Department of Global Health, University of Washington, Seattle, WA 98102, USA
| | - Suzanne Scarlata
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794-8661, USA
| | - Fadila Bouamr
- Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD 20894, USA.
| |
Collapse
|
24
|
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
Collapse
Affiliation(s)
- Guangdi Li
- Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| | - Erik De Clercq
- KU Leuven-University of Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Leuven, Belgium
| |
Collapse
|
25
|
Hellmund C, Lever AML. Coordination of Genomic RNA Packaging with Viral Assembly in HIV-1. Viruses 2016; 8:E192. [PMID: 27428992 PMCID: PMC4974527 DOI: 10.3390/v8070192] [Citation(s) in RCA: 8] [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: 06/16/2016] [Revised: 07/04/2016] [Accepted: 07/07/2016] [Indexed: 12/15/2022] Open
Abstract
The tremendous progress made in unraveling the complexities of human immunodeficiency virus (HIV) replication has resulted in a library of drugs to target key aspects of the replication cycle of the virus. Yet, despite this accumulated wealth of knowledge, we still have much to learn about certain viral processes. One of these is virus assembly, where the viral genome and proteins come together to form infectious progeny. Here we review this topic from the perspective of how the route to production of an infectious virion is orchestrated by the viral genome, and we compare and contrast aspects of the assembly mechanisms employed by HIV-1 with those of other RNA viruses.
Collapse
Affiliation(s)
- Chris Hellmund
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.
| | - Andrew M L Lever
- Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.
| |
Collapse
|
26
|
HIV Genome-Wide Protein Associations: a Review of 30 Years of Research. Microbiol Mol Biol Rev 2016; 80:679-731. [PMID: 27357278 DOI: 10.1128/mmbr.00065-15] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The HIV genome encodes a small number of viral proteins (i.e., 16), invariably establishing cooperative associations among HIV proteins and between HIV and host proteins, to invade host cells and hijack their internal machineries. As a known example, the HIV envelope glycoprotein GP120 is closely associated with GP41 for viral entry. From a genome-wide perspective, a hypothesis can be worked out to determine whether 16 HIV proteins could develop 120 possible pairwise associations either by physical interactions or by functional associations mediated via HIV or host molecules. Here, we present the first systematic review of experimental evidence on HIV genome-wide protein associations using a large body of publications accumulated over the past 3 decades. Of 120 possible pairwise associations between 16 HIV proteins, at least 34 physical interactions and 17 functional associations have been identified. To achieve efficient viral replication and infection, HIV protein associations play essential roles (e.g., cleavage, inhibition, and activation) during the HIV life cycle. In either a dispensable or an indispensable manner, each HIV protein collaborates with another viral protein to accomplish specific activities that precisely take place at the proper stages of the HIV life cycle. In addition, HIV genome-wide protein associations have an impact on anti-HIV inhibitors due to the extensive cross talk between drug-inhibited proteins and other HIV proteins. Overall, this study presents for the first time a comprehensive overview of HIV genome-wide protein associations, highlighting meticulous collaborations between all viral proteins during the HIV life cycle.
Collapse
|
27
|
The Race against Protease Activation Defines the Role of ESCRTs in HIV Budding. PLoS Pathog 2016; 12:e1005657. [PMID: 27280284 PMCID: PMC4900648 DOI: 10.1371/journal.ppat.1005657] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 05/03/2016] [Indexed: 11/26/2022] Open
Abstract
HIV virions assemble on the plasma membrane and bud out of infected cells using interactions with endosomal sorting complexes required for transport (ESCRTs). HIV protease activation is essential for maturation and infectivity of progeny virions, however, the precise timing of protease activation and its relationship to budding has not been well defined. We show that compromised interactions with ESCRTs result in delayed budding of virions from host cells. Specifically, we show that Gag mutants with compromised interactions with ALIX and Tsg101, two early ESCRT factors, have an average budding delay of ~75 minutes and ~10 hours, respectively. Virions with inactive proteases incorporated the full Gag-Pol and had ~60 minutes delay in budding. We demonstrate that during budding delay, activated proteases release critical HIV enzymes back to host cytosol leading to production of non-infectious progeny virions. To explain the molecular mechanism of the observed budding delay, we modulated the Pol size artificially and show that virion release delays are size-dependent and also show size-dependency in requirements for Tsg101 and ALIX. We highlight the sensitivity of HIV to budding “on-time” and suggest that budding delay is a potent mechanism for inhibition of infectious retroviral release. ESCRTs are implicated in cellular processes which require fission of budding membranes. Likely the most studied of these processes is the HIV-ESCRT interactions. The canonical view is that interference with ESCRT recruitment results in a late budding arrest of virions at the plasma membrane and this mechanistic view of ESCRTs has shaped our understanding of their function in almost all cell biology. In this manuscript, we present a full kinetic analysis of HIV virion release under all known mutations in Gag that affect HIV-ESCRT interactions. Our data show that contrary to the canonical view, a defect in ESCRT recruitment does not inhibit virion budding, however it creates a delay. We further show that during budding delay, activated proteases release critical HIV enzymes back to host cytosol, leading to budding of non-infectious progeny virions. We suggest that budding delay is a potent mechanism for inhibition of infectious retroviral release and can be the basis for developing antiviral treatments which slow the budding process and therefore disproportionally affect infectious retroviral release. We also suggest that such budding delay may be one of the mechanisms underlying cellular innate immune responses which inhibit the spread of retroviral infection.
Collapse
|
28
|
Mori M, Kovalenko L, Lyonnais S, Antaki D, Torbett BE, Botta M, Mirambeau G, Mély Y. Nucleocapsid Protein: A Desirable Target for Future Therapies Against HIV-1. Curr Top Microbiol Immunol 2015; 389:53-92. [PMID: 25749978 PMCID: PMC7122173 DOI: 10.1007/82_2015_433] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The currently available anti-HIV-1 therapeutics is highly beneficial to infected patients. However, clinical failures occur as a result of the ability of HIV-1 to rapidly mutate. One approach to overcome drug resistance is to target HIV-1 proteins that are highly conserved among phylogenetically distant viral strains and currently not targeted by available therapies. In this respect, the nucleocapsid (NC) protein, a zinc finger protein, is particularly attractive, as it is highly conserved and plays a central role in virus replication, mainly by interacting with nucleic acids. The compelling rationale for considering NC as a viable drug target is illustrated by the fact that point mutants of this protein lead to noninfectious viruses and by the inability to select viruses resistant to a first generation of anti-NC drugs. In our review, we discuss the most relevant properties and functions of NC, as well as recent developments of small molecules targeting NC. Zinc ejectors show strong antiviral activity, but are endowed with a low therapeutic index due to their lack of specificity, which has resulted in toxicity. Currently, they are mainly being investigated for use as topical microbicides. Greater specificity may be achieved by using non-covalent NC inhibitors (NCIs) targeting the hydrophobic platform at the top of the zinc fingers or key nucleic acid partners of NC. Within the last few years, innovative methodologies have been developed to identify NCIs. Though the antiviral activity of the identified NCIs needs still to be improved, these compounds strongly support the druggability of NC and pave the way for future structure-based design and optimization of efficient NCIs.
Collapse
Affiliation(s)
- Mattia Mori
- Dipartimento di Biotecnologie Chimica e Farmacia, Università degli Studi di Siena, via A. Moro 2, 53100, Siena, Italy
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Aiamkitsumrit B, Sullivan NT, Nonnemacher MR, Pirrone V, Wigdahl B. Human Immunodeficiency Virus Type 1 Cellular Entry and Exit in the T Lymphocytic and Monocytic Compartments: Mechanisms and Target Opportunities During Viral Disease. Adv Virus Res 2015; 93:257-311. [PMID: 26111588 DOI: 10.1016/bs.aivir.2015.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During the course of human immunodeficiency virus type 1 infection, a number of cell types throughout the body are infected, with the majority of cells representing CD4+ T cells and cells of the monocyte-macrophage lineage. Both types of cells express, to varying levels, the primary receptor molecule, CD4, as well as one or both of the coreceptors, CXCR4 and CCR5. Viral tropism is determined by both the coreceptor utilized for entry and the cell type infected. Although a single virus may have the capacity to infect both a CD4+ T cell and a cell of the monocyte-macrophage lineage, the mechanisms involved in both the entry of the virus into the cell and the viral egress from the cell during budding and viral release differ depending on the cell type. These host-virus interactions and processes can result in the differential targeting of different cell types by selected viral quasispecies and the overall amount of infectious virus released into the extracellular environment or by direct cell-to-cell spread of viral infectivity. This review covers the major steps of virus entry and egress with emphasis on the parts of the replication process that lead to differences in how the virus enters, replicates, and buds from different cellular compartments, such as CD4+ T cells and cells of the monocyte-macrophage lineage.
Collapse
Affiliation(s)
- Benjamas Aiamkitsumrit
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA; Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Neil T Sullivan
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA; Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Michael R Nonnemacher
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA; Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Vanessa Pirrone
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA; Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Brian Wigdahl
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA; Center for Molecular Virology and Translational Neuroscience, Institute for Molecular Medicine and Infectious Disease, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
| |
Collapse
|
30
|
Super-resolution imaging of ESCRT-proteins at HIV-1 assembly sites. PLoS Pathog 2015; 11:e1004677. [PMID: 25710462 PMCID: PMC4339578 DOI: 10.1371/journal.ppat.1004677] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/12/2015] [Indexed: 11/19/2022] Open
Abstract
The cellular endosomal sorting complex required for transport (ESCRT) machinery is involved in membrane budding processes, such as multivesicular biogenesis and cytokinesis. In HIV-infected cells, HIV-1 hijacks the ESCRT machinery to drive HIV release. Early in the HIV-1 assembly process, the ESCRT-I protein Tsg101 and the ESCRT-related protein ALIX are recruited to the assembly site. Further downstream, components such as the ESCRT-III proteins CHMP4 and CHMP2 form transient membrane associated lattices, which are involved in virus-host membrane fission. Although various geometries of ESCRT-III assemblies could be observed, the actual membrane constriction and fission mechanism is not fully understood. Fission might be driven from inside the HIV-1 budding neck by narrowing the membranes from the outside by larger lattices surrounding the neck, or from within the bud. Here, we use super-resolution fluorescence microscopy to elucidate the size and structure of the ESCRT components Tsg101, ALIX, CHMP4B and CHMP2A during HIV-1 budding below the diffraction limit. To avoid the deleterious effects of using fusion proteins attached to ESCRT components, we performed measurements on the endogenous protein or, in the case of CHMP4B, constructs modified with the small HA tag. Due to the transient nature of the ESCRT interactions, the fraction of HIV-1 assembly sites with colocalizing ESCRT complexes was low (1.5%-3.4%). All colocalizing ESCRT clusters exhibited closed, circular structures with an average size (full-width at half-maximum) between 45 and 60 nm or a diameter (determined using a Ripley's L-function analysis) of roughly 60 to 100 nm. The size distributions for colocalizing clusters were narrower than for non-colocalizing clusters, and significantly smaller than the HIV-1 bud. Hence, our results support a membrane scission process driven by ESCRT protein assemblies inside a confined structure, such as the bud neck, rather than by large lattices around the neck or in the bud lumen. In the case of ALIX, a cloud of individual molecules surrounding the central clusters was often observed, which we attribute to ALIX molecules incorporated into the nascent HIV-1 Gag shell. Experiments performed using YFP-tagged Tsg101 led to an over 10-fold increase in ESCRT structures colocalizing with HIV-1 budding sites indicating an influence of the fusion protein tag on the function of the ESCRT protein.
Collapse
|
31
|
Parvez MK. HBV and HIV co-infection: Impact on liver pathobiology and therapeutic approaches. World J Hepatol 2015; 7:121-126. [PMID: 25625003 PMCID: PMC4295189 DOI: 10.4254/wjh.v7.i1.121] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 11/10/2014] [Indexed: 02/06/2023] Open
Abstract
The consequences of hepatitis B virus (HBV) and human immunodeficiency virus (HIV) co-infection on progression of severe liver diseases is a serious public health issue, worldwide. In the co-infection cases, about 90% of HIV-infected population is seropositive for HBV where approximately 5%-40% individuals are chronically infected. In HIV co-infected individuals, liver-related mortality is estimated over 17 times higher than those with HBV mono-infection. The spectrum of HIV-induced liver diseases includes hepatitis, steatohepatitis, endothelialitis, necrosis, granulomatosis, cirrhosis and carcinoma. Moreover, HIV co-infection significantly alters the natural history of hepatitis B, and therefore complicates the disease management. Though several studies have demonstrated impact of HIV proteins on hepatocyte biology, only a few data is available on interactions between HBV and HIV proteins. Thus, the clinical spectrum as well as the complexity of the co-infection offers challenging fronts to study the underlying molecular mechanisms, and to design effective therapeutic strategies.
Collapse
|
32
|
Chamontin C, Rassam P, Ferrer M, Racine PJ, Neyret A, Lainé S, Milhiet PE, Mougel M. HIV-1 nucleocapsid and ESCRT-component Tsg101 interplay prevents HIV from turning into a DNA-containing virus. Nucleic Acids Res 2014; 43:336-47. [PMID: 25488808 PMCID: PMC4288153 DOI: 10.1093/nar/gku1232] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
HIV-1, the agent of the AIDS pandemic, is an RNA virus that reverse transcribes its RNA genome (gRNA) into DNA, shortly after its entry into cells. Within cells, retroviral assembly requires thousands of structural Gag proteins and two copies of gRNA as well as cellular factors, which converge to the plasma membrane in a finely regulated timeline. In this process, the nucleocapsid domain of Gag (GagNC) ensures gRNA selection and packaging into virions. Subsequent budding and virus release require the recruitment of the cellular ESCRT machinery. Interestingly, mutating GagNC results into the release of DNA-containing viruses, by promo-ting reverse transcription (RTion) prior to virus release, through an unknown mechanism. Therefore, we explored the biogenesis of these DNA-containing particles, combining live-cell total internal-reflection fluorescent microscopy, electron microscopy, trans-complementation assays and biochemical characterization of viral particles. Our results reveal that DNA virus production is the consequence of budding defects associated with Gag aggregation at the plasma membrane and deficiency in the recruitment of Tsg101, a key ESCRT-I component. Indeed, targeting Tsg101 to virus assembly sites restores budding, restricts RTion and favors RNA packaging into viruses. Altogether, our results highlight the role of GagNC in the spatiotemporal control of RTion, via an ESCRT-I-dependent mechanism.
Collapse
Affiliation(s)
- Célia Chamontin
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| | - Patrice Rassam
- Centre de Biochimie Structurale, UMR5048 CNRS, University of Montpellier, 34090 Montpellier, France
| | - Mireia Ferrer
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| | - Pierre-Jean Racine
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| | - Aymeric Neyret
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| | - Sébastien Lainé
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| | - Pierre-Emmanuel Milhiet
- Centre de Biochimie Structurale, UMR5048 CNRS, University of Montpellier, 34090 Montpellier, France U1054 INSERM, 30090 Montpellier, France
| | - Marylène Mougel
- CPBS, UMR5236 CNRS, University of Montpellier, 34293 Montpellier, France
| |
Collapse
|
33
|
Role of the nucleocapsid region in HIV-1 Gag assembly as investigated by quantitative fluorescence-based microscopy. Virus Res 2014; 193:78-88. [PMID: 25016037 DOI: 10.1016/j.virusres.2014.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 11/19/2022]
Abstract
The Gag precursor of HIV-1, formed of the four proteic regions matrix (MA), capsid (CA), nucleocapsid (NC) and p6, orchestrates virus morphogenesis. This complex process relies on three major interactions, NC-RNA acting as a scaffold, CA-CA and MA-membrane that targets assembly to the plasma membrane (PM). The characterization of the molecular mechanism of retroviral assembly has extensively benefited from biochemical studies and more recently an important step forward was achieved with the use of fluorescence-based techniques and fluorescently labeled viral proteins. In this review, we summarize the findings obtained with such techniques, notably quantitative-based approaches, which highlight the role of the NC region in Gag assembly.
Collapse
|
34
|
Stauffer S, Rahman SA, de Marco A, Carlson LA, Glass B, Oberwinkler H, Herold N, Briggs JAG, Müller B, Grünewald K, Kräusslich HG. The nucleocapsid domain of Gag is dispensable for actin incorporation into HIV-1 and for association of viral budding sites with cortical F-actin. J Virol 2014; 88:7893-903. [PMID: 24789788 PMCID: PMC4097806 DOI: 10.1128/jvi.00428-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/24/2014] [Indexed: 12/24/2022] Open
Abstract
Actin and actin-binding proteins are incorporated into HIV-1 particles, and F-actin has been suggested to bind the NC domain in HIV-1 Gag. Furthermore, F-actin has been frequently observed in the vicinity of HIV-1 budding sites by cryo-electron tomography (cET). Filamentous structures emanating from viral buds and suggested to correspond to actin filaments have been observed by atomic force microscopy. To determine whether the NC domain of Gag is required for actin association with viral buds and for actin incorporation into HIV-1, we performed comparative analyses of virus-like particles (VLPs) obtained by expression of wild-type HIV-1 Gag or a Gag variant where the entire NC domain had been replaced by a dimerizing leucine zipper [Gag(LZ)]. The latter protein yielded efficient production of VLPs with near-wild-type assembly kinetics and size and exhibited a regular immature Gag lattice. Typical HIV-1 budding sites were detected by using cET in cells expressing either Gag or Gag(LZ), and no difference was observed regarding the association of buds with the F-actin network. Furthermore, actin was equally incorporated into wild-type HIV-1 and Gag- or Gag(LZ)-derived VLPs, with less actin per particle observed than had been reported previously. Incorporation appeared to correlate with the relative intracellular actin concentration, suggesting an uptake of cytosol rather than a specific recruitment of actin. Thus, the NC domain in HIV-1 Gag does not appear to have a role in actin recruitment or actin incorporation into HIV-1 particles. Importance: HIV-1 particles bud from the plasma membrane, which is lined by a network of actin filaments. Actin was found to interact with the nucleocapsid domain of the viral structural protein Gag and is incorporated in significant amounts into HIV-1 particles, suggesting that it may play an active role in virus release. Using electron microscopy techniques, we previously observed bundles of actin filaments near HIV-1 buds, often seemingly in contact with the Gag layer. Here, we show that this spatial association is observed independently of the proposed actin-binding domain of HIV-1. The absence of this domain also did not affect actin incorporation and had a minor effect on the viral assembly rate. Furthermore, actin was not enriched in the virus compared to the average levels in the respective producing cell. Our data argue against a specific recruitment of actin to HIV-1 budding sites by the nucleocapsid domain of Gag.
Collapse
Affiliation(s)
- Sarah Stauffer
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Sheikh Abdul Rahman
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Alex de Marco
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Lars-Anders Carlson
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Heike Oberwinkler
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Nikolas Herold
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Kay Grünewald
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| |
Collapse
|
35
|
ALIX is recruited temporarily into HIV-1 budding sites at the end of gag assembly. PLoS One 2014; 9:e96950. [PMID: 24834918 PMCID: PMC4023924 DOI: 10.1371/journal.pone.0096950] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 04/13/2014] [Indexed: 11/28/2022] Open
Abstract
Polymerization of Gag on the inner leaflet of the plasma membrane drives the assembly of Human Immunodeficiency Virus 1 (HIV-1). Gag recruits components of the endosomal sorting complexes required for transport (ESCRT) to facilitate membrane fission and virion release. ESCRT assembly is initiated by recruitment of ALIX and TSG101/ESCRT-I, which bind directly to the viral Gag protein and then recruit the downstream ESCRT-III and VPS4 factors to complete the budding process. In contrast to previous models, we show that ALIX is recruited transiently at the end of Gag assembly, and that most ALIX molecules are recycled into the cytosol as the virus buds, although a subset remains within the virion. Our experiments imply that ALIX is recruited to the neck of the assembling virion and is mostly recycled after virion release.
Collapse
|
36
|
Abstract
Enveloped viruses escape infected cells by budding through limiting membranes. In the decade since the discovery that HIV recruits cellular ESCRT (endosomal sorting complexes required for transport) machinery to facilitate viral budding, this pathway has emerged as the major escape route for enveloped viruses. In cells, the ESCRT pathway catalyzes analogous membrane fission events required for the abscission stage of cytokinesis and for a series of "reverse topology" vesiculation events. Studies of enveloped virus budding are therefore providing insights into the complex cellular mechanisms of cell division and membrane protein trafficking (and vice versa). Here, we review how viruses mimic cellular recruiting signals to usurp the ESCRT pathway, discuss mechanistic models for ESCRT pathway functions, and highlight important research frontiers.
Collapse
Affiliation(s)
- Jörg Votteler
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112-5650, USA
| | | |
Collapse
|
37
|
Abstract
BACKGROUND Retroviruses and many other enveloped viruses usurp the cellular ESCRT pathway to bud from cells. However, the stepwise process of ESCRT-mediated virus budding can be challenging to analyze in retroviruses like HIV-1 that recruit multiple different ESCRT factors to initiate budding. RESULTS In this study, we characterized the ESCRT factor requirements for budding of Equine Infectious Anemia Virus (EIAV), whose only known direct ESCRT protein interaction is with ALIX. siRNA depletion of endogenous ESCRT proteins and "rescue" experiments with exogenous siRNA-resistant wild type and mutant constructs revealed budding requirements for the following ESCRT proteins: ALIX, CHMP4B, CHMP2A and VPS4A or VPS4B. EIAV budding was inhibited by point mutations that abrogate the direct interactions between ALIX:CHMP4B, CHMP4B:CHMP2A, and CHMP2A:VPS4A/B, indicating that each of these interactions is required for EIAV budding. Unexpectedly, CHMP4B depletion led to formation of multi-lobed and long tubular EIAV virions. CONCLUSIONS We conclude that EIAV budding requires an ESCRT protein network that comprises EIAV Gag-ALIX-CHMP4B-CHMP2A-VPS4 interactions. Our experiments also suggest that CHMP4B recruitment/polymerization helps control Gag polymerization and/or processing to ensure that ESCRT factor assembly and membrane fission occur at the proper stage of virion assembly. These studies help establish EIAV as a streamlined model system for dissecting the stepwise processes of lentivirus assembly and ESCRT-mediated budding.
Collapse
Affiliation(s)
- Virginie Sandrin
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City 84112-5650, Utah, USA
| | - Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City 84112-5650, Utah, USA
| |
Collapse
|
38
|
Sundquist WI, Kräusslich HG. HIV-1 assembly, budding, and maturation. Cold Spring Harb Perspect Med 2013; 2:a006924. [PMID: 22762019 DOI: 10.1101/cshperspect.a006924] [Citation(s) in RCA: 514] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A defining property of retroviruses is their ability to assemble into particles that can leave producer cells and spread infection to susceptible cells and hosts. Virion morphogenesis can be divided into three stages: assembly, wherein the virion is created and essential components are packaged; budding, wherein the virion crosses the plasma membrane and obtains its lipid envelope; and maturation, wherein the virion changes structure and becomes infectious. All of these stages are coordinated by the Gag polyprotein and its proteolytic maturation products, which function as the major structural proteins of the virus. Here, we review our current understanding of the mechanisms of HIV-1 assembly, budding, and maturation, starting with a general overview and then providing detailed descriptions of each of the different stages of virion morphogenesis.
Collapse
Affiliation(s)
- Wesley I Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, USA.
| | | |
Collapse
|
39
|
Grover JR, Llewellyn GN, Soheilian F, Nagashima K, Veatch SL, Ono A. Roles played by capsid-dependent induction of membrane curvature and Gag-ESCRT interactions in tetherin recruitment to HIV-1 assembly sites. J Virol 2013; 87:4650-64. [PMID: 23408603 PMCID: PMC3624355 DOI: 10.1128/jvi.03526-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/04/2013] [Indexed: 12/17/2022] Open
Abstract
Tetherin/BST-2 (here called tetherin) is an antiviral protein that restricts release of diverse enveloped viruses from infected cells through physically tethering virus envelope and host plasma membrane. For HIV-1, specific recruitment of tetherin to assembly sites has been observed as its colocalization with the viral structural protein Gag or its accumulation in virus particles. Because of its broad range of targets, we hypothesized that tetherin is recruited through conserved features shared among various enveloped viruses, such as lipid raft association, membrane curvature, or ESCRT dependence. We observed that reduction of cellular cholesterol does not block tetherin anti-HIV-1 function, excluding an essential role for lipid rafts. In contrast, mutations in the capsid domain of Gag, which inhibit induction of membrane curvature, prevented tetherin-Gag colocalization detectable by confocal microscopy. Disruption of Gag-ESCRT interactions also inhibited tetherin-Gag colocalization when disruption was accomplished via amino acid substitutions in late domain motifs, expression of a dominant-negative Tsg101 derivative, or small interfering RNA (siRNA)-mediated depletion of Tsg101 or Alix. However, further analyses of these conditions by quantitative superresolution localization microscopy revealed that Gag-tetherin coclustering is significantly reduced but persists at intermediate levels. Notably, this residual tetherin recruitment was still sufficient for the full restriction of HIV-1 release. Unlike the late domain mutants, the capsid mutants defective in inducing membrane curvature showed little or no coclustering with tetherin in superresolution analyses. These results support a model in which both Gag-induced membrane curvature and Gag-ESCRT interactions promote tetherin recruitment, but the recruitment level achieved by the former is sufficient for full restriction.
Collapse
Affiliation(s)
| | - G. Nicholas Llewellyn
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ferri Soheilian
- Electron Microscopy Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Kunio Nagashima
- Electron Microscopy Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Sarah L. Veatch
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Akira Ono
- Department of Microbiology and Immunology
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| |
Collapse
|
40
|
Bell NM, Lever AML. HIV Gag polyprotein: processing and early viral particle assembly. Trends Microbiol 2013; 21:136-44. [PMID: 23266279 DOI: 10.1016/j.tim.2012.11.006] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/22/2012] [Accepted: 11/29/2012] [Indexed: 12/22/2022]
Affiliation(s)
- Neil M Bell
- Department of Medicine, University of Cambridge, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
| | | |
Collapse
|
41
|
Lyonnais S, Gorelick RJ, Heniche-Boukhalfa F, Bouaziz S, Parissi V, Mouscadet JF, Restle T, Gatell JM, Le Cam E, Mirambeau G. A protein ballet around the viral genome orchestrated by HIV-1 reverse transcriptase leads to an architectural switch: from nucleocapsid-condensed RNA to Vpr-bridged DNA. Virus Res 2013; 171:287-303. [PMID: 23017337 PMCID: PMC3552025 DOI: 10.1016/j.virusres.2012.09.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Revised: 09/13/2012] [Accepted: 09/14/2012] [Indexed: 12/15/2022]
Abstract
HIV-1 reverse transcription is achieved in the newly infected cell before viral DNA (vDNA) nuclear import. Reverse transcriptase (RT) has previously been shown to function as a molecular motor, dismantling the nucleocapsid complex that binds the viral genome as soon as plus-strand DNA synthesis initiates. We first propose a detailed model of this dismantling in close relationship with the sequential conversion from RNA to double-stranded (ds) DNA, focusing on the nucleocapsid protein (NCp7). The HIV-1 DNA-containing pre-integration complex (PIC) resulting from completion of reverse transcription is translocated through the nuclear pore. The PIC nucleoprotein architecture is poorly understood but contains at least two HIV-1 proteins initially from the virion core, namely integrase (IN) and the viral protein r (Vpr). We next present a set of electron micrographs supporting that Vpr behaves as a DNA architectural protein, initiating multiple DNA bridges over more than 500 base pairs (bp). These complexes are shown to interact with NCp7 bound to single-stranded nucleic acid regions that are thought to maintain IN binding during dsDNA synthesis, concurrently with nucleocapsid complex dismantling. This unexpected binding of Vpr conveniently leads to a compacted but filamentous folding of the vDNA that should favor its nuclear import. Finally, nucleocapsid-like aggregates engaged in dsDNA synthesis appear to efficiently bind to F-actin filaments, a property that may be involved in targeting complexes to the nuclear envelope. More generally, this article highlights unique possibilities offered by in vitro reconstitution approaches combined with macromolecular imaging to gain insights into the mechanisms that alter the nucleoprotein architecture of the HIV-1 genome, ultimately enabling its insertion into the nuclear chromatin.
Collapse
MESH Headings
- DNA Packaging
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Genome, Viral
- HIV Integrase/genetics
- HIV Integrase/metabolism
- HIV Reverse Transcriptase/genetics
- HIV Reverse Transcriptase/metabolism
- HIV-1/chemistry
- HIV-1/enzymology
- HIV-1/genetics
- HIV-1/metabolism
- Humans
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Reverse Transcription
- gag Gene Products, Human Immunodeficiency Virus/genetics
- gag Gene Products, Human Immunodeficiency Virus/metabolism
- vpr Gene Products, Human Immunodeficiency Virus
Collapse
Affiliation(s)
| | - Robert J. Gorelick
- AIDS and Cancer Virus Program; SAIC-Frederick, Inc.; Frederick National Laboratory for Cancer Research; Frederick, MD USA
| | - Fatima Heniche-Boukhalfa
- Maintenance des génomes, Microscopies Moléculaire et Bionanosciences; UMR 8126 CNRS-Université Paris Sud, Villejuif, F-94805, France
| | - Serge Bouaziz
- Laboratoire de Cristallographie et RMN biologiques; UMR 8015 CNRS-Université Paris Descartes; Paris, F-75006, France
| | - Vincent Parissi
- Laboratoire de Microbiologie Fondamentale et Pathogénicité, UMR5234 CNRS-Université Bordeaux Segalen, France
| | | | - Tobias Restle
- Institute of Molecular Medicine, University of Lübeck, Center for Structural and Cell Biology in Medicine (CSCM), D-23538 Lübeck, Germany
| | | | - Eric Le Cam
- Maintenance des génomes, Microscopies Moléculaire et Bionanosciences; UMR 8126 CNRS-Université Paris Sud, Villejuif, F-94805, France
| | - Gilles Mirambeau
- AIDS Research Group; IDIBAPS; E-08036 Barcelona, Spain
- Faculté de Biologie; UPMC Sorbonne Universités; Paris, F-75005, France
| |
Collapse
|
42
|
Meng B, Lever AM. Wrapping up the bad news: HIV assembly and release. Retrovirology 2013; 10:5. [PMID: 23305486 PMCID: PMC3558412 DOI: 10.1186/1742-4690-10-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 12/21/2012] [Indexed: 02/02/2023] Open
Abstract
The late Nobel Laureate Sir Peter Medawar once memorably described viruses as ‘bad news wrapped in protein’. Virus assembly in HIV is a remarkably well coordinated process in which the virus achieves extracellular budding using primarily intracellular budding machinery and also the unusual phenomenon of export from the cell of an RNA. Recruitment of the ESCRT system by HIV is one of the best documented examples of the comprehensive way in which a virus hijacks a normal cellular process. This review is a summary of our current understanding of the budding process of HIV, from genomic RNA capture through budding and on to viral maturation, but centering on the proteins of the ESCRT pathway and highlighting some recent advances in our understanding of the cellular components involved and the complex interplay between the Gag protein and the genomic RNA.
Collapse
Affiliation(s)
- Bo Meng
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
| | | |
Collapse
|
43
|
In vitro reconstitution of the ordered assembly of the endosomal sorting complex required for transport at membrane-bound HIV-1 Gag clusters. Proc Natl Acad Sci U S A 2012; 109:16928-33. [PMID: 23027949 DOI: 10.1073/pnas.1211759109] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Most membrane-enveloped viruses depend on host proteins of the endosomal sorting complex required for transport (ESCRT) machinery for their release. HIV-1 is the prototypic ESCRT-dependent virus. The direct interactions between HIV-1 and the early ESCRT factors TSG101 and ALIX have been mapped in detail. However, the full pathway of ESCRT recruitment to HIV-1 budding sites, which culminates with the assembly of the late-acting CHMP4, CHMP3, CHMP2, and CHMP1 subunits, is less completely understood. Here, we report the biochemical reconstitution of ESCRT recruitment to viral assembly sites, using purified proteins and giant unilamellar vesicles. The myristylated full-length Gag protein of HIV-1 was purified to monodispersity. Myr-Gag forms clusters on giant unilamellar vesicle membranes containing the plasma membrane lipid PI(4,5)P(2). These Gag clusters package a fluorescent oligonucleotide, and recruit early ESCRT complexes ESCRT-I or ALIX with the appropriate dependence on the Gag PTAP and LYP(X)(n)L motifs. ALIX directly recruits the key ESCRT-III subunit CHMP4. ESCRT-I can only recruit CHMP4 when ESCRT-II and CHMP6 are present as intermediary factors. Downstream of CHMP4, CHMP3 and CHMP2 assemble synergistically, with the presence of both subunits required for efficient recruitment. The very late-acting factor CHMP1 is not recruited unless the pathway is completed through CHMP3 and CHMP2. These findings define the minimal sets of components needed to complete ESCRT assembly at HIV-1 budding sites, and provide a starting point for in vitro structural and biophysical dissection of the system.
Collapse
|
44
|
Abstract
Expression of a retroviral Gag protein in mammalian cells leads to the assembly of virus particles. In vitro, recombinant Gag proteins are soluble but assemble into virus-like particles (VLPs) upon addition of nucleic acid. We have proposed that Gag undergoes a conformational change when it is at a high local concentration and that this change is an essential prerequisite for particle assembly; perhaps one way that this condition can be fulfilled is by the cooperative binding of Gag molecules to nucleic acid. We have now characterized the assembly in human cells of HIV-1 Gag molecules with a variety of defects, including (i) inability to bind to the plasma membrane, (ii) near-total inability of their capsid domains to engage in dimeric interaction, and (iii) drastically compromised ability to bind RNA. We find that Gag molecules with any one of these defects still retain some ability to assemble into roughly spherical objects with roughly correct radius of curvature. However, combination of any two of the defects completely destroys this capability. The results suggest that these three functions are somewhat redundant with respect to their contribution to particle assembly. We suggest that they are alternative mechanisms for the initial concentration of Gag molecules; under our experimental conditions, any two of the three is sufficient to lead to some semblance of correct assembly.
Collapse
|
45
|
Identification of the HIV-1 NC binding interface in Alix Bro1 reveals a role for RNA. J Virol 2012; 86:11608-15. [PMID: 22896625 DOI: 10.1128/jvi.01260-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
HIV-1 recruits members of ESCRT, the cell membrane fission machinery that promotes virus exit. HIV-1 Gag protein gains access to ESCRT directly by binding Alix, an ESCRT-associated protein that promotes budding. The Alix Bro1 and V domains bind Gag NC and p6 regions, respectively. Whereas V-p6 binding and function are well characterized, residues in Bro1 that interact with NC and their functional contribution to Alix-mediated HIV-1 budding are unknown. We mapped Bro1 residues that constitute the NC binding interface and found that they are critical for function. Intriguingly, residues involved in interactions on both sides of the Bro1-NC interface are positively charged, suggesting the involvement of a negatively charged cellular factor serving as a bridge. Nuclease treatment eliminated Bro1-NC interactions, revealing the involvement of RNA. These findings establish a direct role for NC in mediating interactions with ESCRT necessary for virus release and report the first evidence of RNA involvement in such recruitments.
Collapse
|
46
|
Extracellular vesicles and their convergence with viral pathways. Adv Virol 2012; 2012:767694. [PMID: 22888349 PMCID: PMC3410301 DOI: 10.1155/2012/767694] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 06/06/2012] [Indexed: 01/01/2023] Open
Abstract
Extracellular vesicles (microvesicles), such as exosomes and shed microvesicles, contain a variety of molecules including proteins, lipids, and nucleic acids. Microvesicles appear mostly to originate from multivesicular bodies or to bud from the plasma membrane. Here, we review the convergence of microvesicle biogenesis and aspects of viral assembly and release pathways. Herpesviruses and retroviruses, amongst others, recruit several elements from the microvesicle biogenesis pathways for functional virus release. In addition, noninfectious pleiotropic virus-like vesicles can be released, containing viral and cellular components. We highlight the heterogeneity of microvesicle function during viral infection, addressing microvesicles that can either block or enhance infection, or cause immune dysregulation through bystander action in the immune system. Finally, endogenous retrovirus and retrotransposon elements deposited in our genomes millions of years ago can be released from cells within microvesicles, suggestive of a viral origin of the microvesicle system or perhaps of an evolutionary conserved system of virus-vesicle codependence. More research is needed to further elucidate the complex function of the various microvesicles produced during viral infection, possibly revealing new therapeutic intervention strategies.
Collapse
|
47
|
Abstract
We recently reported that human immunodeficiency virus type 1 (HIV-1) carrying PTAP and LYPX(n)L L domains ceased budding when the nucleocapsid (NC) domain was mutated, suggesting a role for NC in HIV-1 release. Here we investigated whether NC involvement in virus release is a property specific to HIV-1 or a general requirement of retroviruses. Specifically, we examined a possible role for NC in the budding of retroviruses relying on divergent L domains and structurally homologous NC domains that harbor diverse protein sequences. We found that NC is critical for the release of viruses utilizing the PTAP motif whether it functions within its native Gag in simian immunodeficiency virus cpzGAB2 (SIVcpzGAB2) or SIVsmmE543 or when it is transplanted into the heterologous Gag protein of equine infectious anemia virus (EIAV). In both cases, virus release was severely diminished even though NC mutant Gag proteins retained the ability to assemble spherical particles. Moreover, budding-defective NC mutants, which displayed particles tethered to the plasma membrane, were triggered to release virus when access to the cell endocytic sorting complex required for transport pathway was restored (i.e., in trans expression of Nedd4.2s). We also examined the role of NC in the budding of EIAV, a retrovirus relying exclusively on the (L)YPX(n)L-type L domain. We found that EIAV late budding defects were rescued by overexpression of the isolated Alix Bro1 domain (Bro1). Bro1-mediated rescue of EIAV release required the wild-type NC. EIAV NC mutants lost interactions with Bro1 and failed to produce viruses despite retaining the ability to self-assemble. Together, our studies establish a role for NC in the budding of retroviruses harboring divergent L domains and evolutionarily diverse NC sequences, suggesting the utilization of a common conserved mechanism and/or cellular factor rather than a specific motif.
Collapse
|
48
|
Dordor A, Poudevigne E, Göttlinger H, Weissenhorn W. Essential and supporting host cell factors for HIV-1 budding. Future Microbiol 2012; 6:1159-70. [PMID: 22004035 DOI: 10.2217/fmb.11.100] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
HIV-1 employs its structural proteins to orchestrate assembly and budding at the plasma membrane of host cells. The Gag polyprotein is sufficient to form virus-like particles in the absence of other viral proteins and provides a platform to interact with numerous cellular factors that regulate Gag trafficking to the site of assembly and budding. Notably endosomal sorting complexes required for transport have attained much attention over the last decade because of their essential role in virion release. Here we review recent advances in understanding the role of host cell factors recruited by Gag during HIV-1 assembly and budding.
Collapse
Affiliation(s)
- Aurelien Dordor
- Unit of Virus Host Cell Interactions UMI 3265 Université Joseph Fourier-EMBL-CNRS, 6 rue Jules Horowitz 38042 Grenoble Cedex 9, France
| | | | | | | |
Collapse
|
49
|
Regulation of CHMP4/ESCRT-III function in human immunodeficiency virus type 1 budding by CC2D1A. J Virol 2012; 86:3746-56. [PMID: 22258254 DOI: 10.1128/jvi.06539-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The detachment of human immunodeficiency type 1 (HIV-1) virions depends on CHPM4 family members, which are late-acting components of the ESCRT pathway that mediate the cleavage of bud necks from the cytosolic side. We now show that in human cells, CHMP4 proteins are to a considerable extent bound to two high-molecular-weight proteins that we have identified as CC2D1A and CC2D1B. Both proteins bind to the core domain of CHMP4B, which has a strong propensity to polymerize and to inhibit HIV-1 budding. Further mapping showed that CC2D1A binds to an N-terminal hairpin within the CHMP4 core that has been implicated in polymerization. Consistent with a model in which CC2D1A and CC2D1B regulate CHMP4 polymerization, the overexpression of CC2D1A inhibited both the release of wild-type HIV-1 and the CHMP4-dependent rescue of an HIV-1 L domain mutant by exogenous ALIX. Furthermore, small interfering RNA against CC2D1A or CC2D1B increased HIV-1 budding under certain conditions. CC2D1A and CC2D1B possess four Drosophila melanogaster 14 (DM14) domains, and we demonstrate that these constitute novel CHMP4 binding modules. The DM14 domain that bound most avidly to CHMP4B was by itself sufficient to inhibit the function of ALIX in HIV-1 budding, indicating that the inhibition occurred through CHMP4 sequestration. However, N-terminal fragments of CC2D1A that did not interact with CHMP4B nevertheless retained a significant level of inhibitory activity. Thus, CC2D1A may also affect HIV-1 budding in a CHMP4-independent manner.
Collapse
|
50
|
Zhai Q, Landesman MB, Robinson H, Sundquist WI, Hill CP. Structure of the Bro1 domain protein BROX and functional analyses of the ALIX Bro1 domain in HIV-1 budding. PLoS One 2011; 6:e27466. [PMID: 22162750 PMCID: PMC3230590 DOI: 10.1371/journal.pone.0027466] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Accepted: 10/17/2011] [Indexed: 11/18/2022] Open
Abstract
Background Bro1 domains are elongated, banana-shaped domains that were first identified in the yeast ESCRT pathway protein, Bro1p. Humans express three Bro1 domain-containing proteins: ALIX, BROX, and HD-PTP, which function in association with the ESCRT pathway to help mediate intraluminal vesicle formation at multivesicular bodies, the abscission stage of cytokinesis, and/or enveloped virus budding. Human Bro1 domains share the ability to bind the CHMP4 subset of ESCRT-III proteins, associate with the HIV-1 NCGag protein, and stimulate the budding of viral Gag proteins. The curved Bro1 domain structure has also been proposed to mediate membrane bending. To date, crystal structures have only been available for the related Bro1 domains from the Bro1p and ALIX proteins, and structures of additional family members should therefore aid in the identification of key structural and functional elements. Methodology/Principal Findings We report the crystal structure of the human BROX protein, which comprises a single Bro1 domain. The Bro1 domains from BROX, Bro1p and ALIX adopt similar overall structures and share two common exposed hydrophobic surfaces. Surface 1 is located on the concave face and forms the CHMP4 binding site, whereas Surface 2 is located at the narrow end of the domain. The structures differ in that only ALIX has an extended loop that projects away from the convex face to expose the hydrophobic Phe105 side chain at its tip. Functional studies demonstrated that mutations in Surface 1, Surface 2, or Phe105 all impair the ability of ALIX to stimulate HIV-1 budding. Conclusions/Significance Our studies reveal similarities in the overall folds and hydrophobic protein interaction sites of different Bro1 domains, and show that a unique extended loop contributes to the ability of ALIX to function in HIV-1 budding.
Collapse
Affiliation(s)
- Qianting Zhai
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Michael B. Landesman
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Howard Robinson
- Department of Biology, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Wesley I. Sundquist
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail: (WIS); (CPH)
| | - Christopher P. Hill
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail: (WIS); (CPH)
| |
Collapse
|