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Woods EJ, Wales DJ. Analysis and interpretation of first passage time distributions featuring rare events. Phys Chem Chem Phys 2024; 26:1640-1657. [PMID: 38059562 DOI: 10.1039/d3cp04199a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
In this contribution we consider theory and associated computational tools to treat the kinetics associated with competing pathways on multifunnel energy landscapes. Multifunnel landscapes are associated with molecular switches and multifunctional materials, and are expected to exhibit multiple relaxation time scales and associated thermodynamic signatures in the heat capacity. Our focus here is on the first passage time distribution, which is encoded in a kinetic transition network containing all the locally stable states and the pathways between them. This network can be renormalised to reduce the dimensionality, while exactly conserving the mean first passage time and approximately conserving the full distribution. The structure of the reduced network can be visualised using disconnectivity graphs. We show how features in the first passage time distribution can be associated with specific kinetic traps, and how the appearance of competing relaxation time scales depends on the starting conditions. The theory is tested for two model landscapes and applied to an atomic cluster and a disordered peptide. Our most important contribution is probably the reconstruction of the full distribution for long time scales, where numerical problems prevent direct calculations. Here we combine accurate treatment of the mean first passage time with the reliable part of the distribution corresponding to faster time scales. Hence we now have a fundamental understanding of both thermodynamic and kinetic signatures of multifunnel landscapes.
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Affiliation(s)
- Esmae J Woods
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, UK
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - David J Wales
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
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2
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Guy C, Mitrea DM, Chou PC, Temirov J, Vignali KM, Liu X, Zhang H, Kriwacki R, Bruchez MP, Watkins SC, Workman CJ, Vignali DAA. LAG3 associates with TCR-CD3 complexes and suppresses signaling by driving co-receptor-Lck dissociation. Nat Immunol 2022; 23:757-767. [PMID: 35437325 PMCID: PMC9106921 DOI: 10.1038/s41590-022-01176-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/03/2022] [Indexed: 02/08/2023]
Abstract
LAG3 is an inhibitory receptor that is highly expressed on exhausted T cells. Although LAG3-targeting immunotherapeutics are currently in clinical trials, how LAG3 inhibits T cell function remains unclear. Here, we show that LAG3 moved to the immunological synapse and associated with the T cell receptor (TCR)-CD3 complex in CD4+ and CD8+ T cells, in the absence of binding to major histocompatibility complex class II-its canonical ligand. Mechanistically, a phylogenetically conserved, acidic, tandem glutamic acid-proline repeat in the LAG3 cytoplasmic tail lowered the pH at the immune synapse and caused dissociation of the tyrosine kinase Lck from the CD4 or CD8 co-receptor, which resulted in a loss of co-receptor-TCR signaling and limited T cell activation. These observations indicated that LAG3 functioned as a signal disruptor in a major histocompatibility complex class II-independent manner, and provide insight into the mechanism of action of LAG3-targeting immunotherapies.
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Affiliation(s)
- Clifford Guy
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Diana M Mitrea
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
- Dewpoint Therapeutics, Boston, MA, USA
| | - Po-Chien Chou
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Jamshid Temirov
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Kate M Vignali
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Tumor Microenvironment Center, UPMC Hillman Cancer Center, Pittsburgh, PA, USA
| | - Xueyan Liu
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN, USA
- Department of Mathematics, University of New Orleans, New Orleans, LA, USA
| | - Hui Zhang
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN, USA
- Division of Biostatistics, Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Richard Kriwacki
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN, USA
| | - Marcel P Bruchez
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
- Molecular Biosensor and Imaging Center, Carnegie Mellon University, Pittsburgh, PA, USA
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Simon C Watkins
- Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Creg J Workman
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA.
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Tumor Microenvironment Center, UPMC Hillman Cancer Center, Pittsburgh, PA, USA.
| | - Dario A A Vignali
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA.
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA.
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Tumor Microenvironment Center, UPMC Hillman Cancer Center, Pittsburgh, PA, USA.
- Cancer Immunology and Immunotherapy Program, UPMC Hillman Cancer Center, Pittsburgh, PA, USA.
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3
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Tzou YM, Shin R, Krishna NR. HIV-1 Virus Interactions With Host Proteins: Interaction of the N-terminal Domain of the HIV-1 Capsid Protein With Human Calmodulin. Nat Prod Commun 2019; 14. [PMID: 31388391 PMCID: PMC6684243 DOI: 10.1177/1934578x19849190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The human immunodeficiency virus (HIV-1 virus) exploits several host factors for assembly, infection, and replication within the infected cells. In this work, we describe the evidence for an interaction of the N-terminal domain of the HIV-1 capsid protein with human calmodulin. The precise role of this interaction within the life cycle of the HIV-1 virus is yet to be defined. Potential roles for this interaction in the viral capsid uncoating are discussed.
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Affiliation(s)
- Ywh-Min Tzou
- Department of Biochemistry and Molecular Genetics, and Comprehensive Cancer Center, University of Alabama at Birmingham, AL, USA.,Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
| | - Ronald Shin
- Department of Biochemistry and Molecular Genetics, and Comprehensive Cancer Center, University of Alabama at Birmingham, AL, USA
| | - N Rama Krishna
- Department of Biochemistry and Molecular Genetics, and Comprehensive Cancer Center, University of Alabama at Birmingham, AL, USA
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4
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Joseph JA, Wales DJ. Intrinsically Disordered Landscapes for Human CD4 Receptor Peptide. J Phys Chem B 2018; 122:11906-11921. [DOI: 10.1021/acs.jpcb.8b08371] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Jerelle A. Joseph
- Department of Chemistry, University of Cambridge, Lenfield Road, Cambridge CB2 1EW, United Kingdom
| | - David J. Wales
- Department of Chemistry, University of Cambridge, Lenfield Road, Cambridge CB2 1EW, United Kingdom
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5
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Abstract
Viroporins are short polypeptides encoded by viruses. These small membrane proteins assemble into oligomers that can permeabilize cellular lipid bilayers, disrupting the physiology of the host to the advantage of the virus. Consequently, efforts during the last few decades have been focused towards the discovery of viroporin channel inhibitors, but in general these have not been successful to produce licensed drugs. Viroporins are also involved in viral pathogenesis by engaging in critical interactions with viral proteins, or disrupting normal host cellular pathways through coordinated interactions with host proteins. These protein-protein interactions (PPIs) may become alternative attractive drug targets for the development of antivirals. In this sense, while thus far most antiviral molecules have targeted viral proteins, focus is moving towards targeting host proteins that are essential for virus replication. In principle, this largely would overcome the problem of resistance, with the possibility of using repositioned existing drugs. The precise role of these PPIs, their strain- and host- specificities, and the structural determination of the complexes involved, are areas that will keep the fields of virology and structural biology occupied for years to come. In the present review, we provide an update of the efforts in the characterization of the main PPIs for most viroporins, as well as the role of viroporins in these PPIs interactions.
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Affiliation(s)
| | - David Bhella
- MRC-University of Glasgow Centre for Virus Research, Glasgow, UK
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6
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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.
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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
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7
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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.
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8
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Druce M, Hulo C, Masson P, Sommer P, Xenarios I, Le Mercier P, De Oliveira T. Improving HIV proteome annotation: new features of BioAfrica HIV Proteomics Resource. DATABASE-THE JOURNAL OF BIOLOGICAL DATABASES AND CURATION 2016; 2016:baw045. [PMID: 27087306 PMCID: PMC4834208 DOI: 10.1093/database/baw045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/11/2016] [Indexed: 02/06/2023]
Abstract
The Human Immunodeficiency Virus (HIV) is one of the pathogens that cause the greatest global concern, with approximately 35 million people currently infected with HIV. Extensive HIV research has been performed, generating a large amount of HIV and host genomic data. However, no effective vaccine that protects the host from HIV infection is available and HIV is still spreading at an alarming rate, despite effective antiretroviral (ARV) treatment. In order to develop effective therapies, we need to expand our knowledge of the interaction between HIV and host proteins. In contrast to virus proteins, which often rapidly evolve drug resistance mutations, the host proteins are essentially invariant within all humans. Thus, if we can identify the host proteins needed for virus replication, such as those involved in transporting viral proteins to the cell surface, we have a chance of interrupting viral replication. There is no proteome resource that summarizes this interaction, making research on this subject a difficult enterprise. In order to fill this gap in knowledge, we curated a resource presents detailed annotation on the interaction between the HIV proteome and host proteins. Our resource was produced in collaboration with ViralZone and used manual curation techniques developed by UniProtKB/Swiss-Prot. Our new website also used previous annotations of the BioAfrica HIV-1 Proteome Resource, which has been accessed by approximately 10 000 unique users a year since its inception in 2005. The novel features include a dedicated new page for each HIV protein, a graphic display of its function and a section on its interaction with host proteins. Our new webpages also add information on the genomic location of each HIV protein and the position of ARV drug resistance mutations. Our improved BioAfrica HIV-1 Proteome Resource fills a gap in the current knowledge of biocuration. Database URL: http://www.bioafrica.net/proteomics/HIVproteome.html
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Affiliation(s)
- Megan Druce
- Africa Centre for Population Health, School of Laboratory Medicine and Medical Sciences, Nelson R. Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa Division of Genetics, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Chantal Hulo
- Swiss-Prot Group, SIB Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Patrick Masson
- Swiss-Prot Group, SIB Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Paula Sommer
- Division of Genetics, School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Ioannis Xenarios
- Swiss-Prot Group, SIB Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Philippe Le Mercier
- Swiss-Prot Group, SIB Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Tulio De Oliveira
- Africa Centre for Population Health, School of Laboratory Medicine and Medical Sciences, Nelson R. Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
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9
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Abstract
Since the discovery that certain small viral membrane proteins, collectively termed as viroporins, can permeabilize host cellular membranes and also behave as ion channels, attempts have been made to link this feature to specific biological roles. In parallel, most viroporins identified so far are virulence factors, and interest has focused toward the discovery of channel inhibitors that would have a therapeutic effect, or be used as research tools to understand the biological roles of viroporin ion channel activity. However, this paradigm is being shifted by the difficulties inherent to small viral membrane proteins, and by the realization that protein-protein interactions and other diverse roles in the virus life cycle may represent an equal, if not, more important target. Therefore, although targeting the channel activity of viroporins can probably be therapeutically useful in some cases, the focus may shift to their other functions in following years. Small-molecule inhibitors have been mostly developed against the influenza A M2 (IAV M2 or AM2). This is not surprising since AM2 is the best characterized viroporin to date, with a well-established biological role in viral pathogenesis combined the most extensive structural investigations conducted, and has emerged as a validated drug target. For other viroporins, these studies are still mostly in their infancy, and together with those for AM2, are the subject of the present review.
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10
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Zhang H, Lin EC, Das BB, Tian Y, Opella SJ. Structural determination of virus protein U from HIV-1 by NMR in membrane environments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3007-3018. [PMID: 26362058 DOI: 10.1016/j.bbamem.2015.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 08/31/2015] [Accepted: 09/05/2015] [Indexed: 11/26/2022]
Abstract
Virus protein U (Vpu) from HIV-1, a small membrane protein composed of a transmembrane helical domain and two α-helices in an amphipathic cytoplasmic domain, down modulates several cellular proteins, including CD4, BST-2/CD317/tetherin, NTB-A, and CCR7. The interactions of Vpu with these proteins interfere with the immune system and enhance the release of newly synthesized virus particles. It is essential to characterize the structure and dynamics of Vpu in order to understand the mechanisms of the protein-protein interactions, and potentially to discover antiviral drugs. In this article, we describe investigations of the cytoplasmic domain of Vpu as well as full-length Vpu by NMR spectroscopy. These studies are complementary to earlier analysis of the transmembrane domain of Vpu. The results suggest that the two helices in the cytoplasmic domain form a U-shape. The length of the inter-helical loop in the cytoplasmic domain and the orientation of the third helix vary with the lipid composition, which demonstrate that the C-terminal helix is relatively flexible, providing accessibility for interaction partners.
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Affiliation(s)
- Hua Zhang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307
| | - Eugene C Lin
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307
| | - Bibhuti B Das
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307
| | - Ye Tian
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307.,Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0307
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11
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Karamanos TK, Kalverda AP, Thompson GS, Radford SE. Mechanisms of amyloid formation revealed by solution NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 88-89:86-104. [PMID: 26282197 PMCID: PMC4568309 DOI: 10.1016/j.pnmrs.2015.05.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/18/2015] [Accepted: 05/18/2015] [Indexed: 05/29/2023]
Abstract
Amyloid fibrils are proteinaceous elongated aggregates involved in more than fifty human diseases. Recent advances in electron microscopy and solid state NMR have allowed the characterization of fibril structures to different extents of refinement. However, structural details about the mechanism of fibril formation remain relatively poorly defined. This is mainly due to the complex, heterogeneous and transient nature of the species responsible for assembly; properties that make them difficult to detect and characterize in structural detail using biophysical techniques. The ability of solution NMR spectroscopy to investigate exchange between multiple protein states, to characterize transient and low-population species, and to study high molecular weight assemblies, render NMR an invaluable technique for studies of amyloid assembly. In this article we review state-of-the-art solution NMR methods for investigations of: (a) protein dynamics that lead to the formation of aggregation-prone species; (b) amyloidogenic intrinsically disordered proteins; and (c) protein-protein interactions on pathway to fibril formation. Together, these topics highlight the power and potential of NMR to provide atomic level information about the molecular mechanisms of one of the most fascinating problems in structural biology.
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Affiliation(s)
- Theodoros K Karamanos
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - Arnout P Kalverda
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Gary S Thompson
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Sheena E Radford
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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12
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Ahalawat N, Arora S, Murarka RK. Structural Ensemble of CD4 Cytoplasmic Tail (402–419) Reveals a Nearly Flat Free-Energy Landscape with Local α-Helical Order in Aqueous Solution. J Phys Chem B 2015; 119:11229-42. [DOI: 10.1021/acs.jpcb.5b03092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Navjeet Ahalawat
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Simran Arora
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Rajesh K. Murarka
- Department
of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal By-pass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
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13
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Involvement of a C-terminal motif in the interference of primate lentiviral Vpu proteins with CD1d-mediated antigen presentation. Sci Rep 2015; 5:9675. [PMID: 25872908 PMCID: PMC4397644 DOI: 10.1038/srep09675] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 03/16/2015] [Indexed: 01/01/2023] Open
Abstract
The HIV-1 accessory protein Vpu is emerging as a critical factor for viral evasion from innate immunity. We have previously shown that the Vpu proteins of two HIV-1 group M subtype B strains (NL4-3 and BaL) down-regulate CD1d from the surface of infected dendritic cells (DCs) and inhibit their crosstalk with the innate invariant natural killer T (iNKT) cells. In the present study, we have investigated the ability of a comprehensive set of primate lentiviral Vpu proteins to interfere with CD1d-mediated immunity. We found that CD1d down-regulation is a conserved function of Vpu proteins from HIV-1 groups M, O and P as well as their direct precursors SIVcpzPtt and SIVgor. At the group M subtype level, subtype C Vpu proteins were significantly weaker CD1d antagonists than subtype B Vpu proteins. Functional characterization of different mutants and chimeras derived from active subtype B and inactive subtype C Vpu proteins revealed that residues in the cytoplasmic domain are important for CD1d down-regulation. Specifically, we identified a C-terminal APW motif characteristic for group M subtype B Vpu proteins necessary for interference with CD1d surface expression. These findings support the notion that Vpu plays an important role in lentiviral evasion from innate immunity.
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14
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Pickering S, Hué S, Kim EY, Reddy S, Wolinsky SM, Neil SJD. Preservation of tetherin and CD4 counter-activities in circulating Vpu alleles despite extensive sequence variation within HIV-1 infected individuals. PLoS Pathog 2014; 10:e1003895. [PMID: 24465210 PMCID: PMC3900648 DOI: 10.1371/journal.ppat.1003895] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 12/06/2013] [Indexed: 01/19/2023] Open
Abstract
The HIV-1 Vpu protein is expressed from a bi-cistronic message late in the viral life cycle. It functions during viral assembly to maximise infectious virus release by targeting CD4 for proteosomal degradation and counteracting the antiviral protein tetherin (BST2/CD317). Single genome analysis of vpu repertoires throughout infection in 14 individuals infected with HIV-1 clade B revealed extensive amino acid diversity of the Vpu protein. For the most part, this variation in Vpu increases over the course of infection and is associated with predicted epitopes of the individual's MHC class I haplotype, suggesting CD8+ T cell pressure is the major driver of Vpu sequence diversity within the host. Despite this variability, the Vpu functions of targeting CD4 and counteracting both physical virus restriction and NF-κB activation by tetherin are rigorously maintained throughout HIV-1 infection. Only a minority of circulating alleles bear lesions in either of these activities at any given time, suggesting functional Vpu mutants are heavily selected against even at later stages of infection. Comparison of Vpu proteins defective for one or several functions reveals novel determinants of CD4 downregulation, counteraction of tetherin restriction, and inhibition of NF-κB signalling. These data affirm the importance of Vpu functions for in vivo persistence of HIV-1 within infected individuals, not simply for transmission, and highlight its potential as a target for antiviral therapy. The accessory protein Vpu, encoded by HIV-1, performs at least two major roles in the virus life cycle, namely the degradation of newly synthesized CD4 molecules and the counteraction of a host antiviral protein, tetherin. These activities promote the release of infectious viruses from host cells, and recent evidence suggests that Vpu function has been crucial for the cross-species transmission of HIV-1 from chimpanzees, and its subsequent pandemic spread in humans. Here we studied the functional variation in Vpu in infected individuals. We found that the Vpu amino acid sequence can be highly variable within an individual, and that this variation is likely to result from host immune responses targeting antigens derived from Vpu. However, despite this variation, Vpu's major functions are preserved, with only a minority of circulating alleles showing defects throughout the course of infection. These data suggest that defective Vpu proteins are selected against within the infected individual, implying that Vpu functions are critical for HIV-1 replication throughout natural infection, not simply at transmission. Therefore Vpu may represent a novel target for antiviral therapy to augment current treatment strategies for HIV/AIDS.
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Affiliation(s)
- Suzanne Pickering
- Department of Infectious Disease, King's College School of Medicine, Guy's Hospital, London, United Kingdom
| | - Stephane Hué
- MRC Centre for Medical Molecular Virology, University College London, London, United Kingdom
| | - Eun-Young Kim
- Department of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Susheel Reddy
- Department of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Steven M. Wolinsky
- Department of Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Stuart J. D. Neil
- Department of Infectious Disease, King's College School of Medicine, Guy's Hospital, London, United Kingdom
- * E-mail:
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15
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Zhang ZR, Bonifacino JS, Hegde RS. Deubiquitinases sharpen substrate discrimination during membrane protein degradation from the ER. Cell 2013; 154:609-22. [PMID: 23890821 PMCID: PMC3732389 DOI: 10.1016/j.cell.2013.06.038] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 05/10/2013] [Accepted: 06/20/2013] [Indexed: 12/25/2022]
Abstract
Newly synthesized membrane proteins are queried by ubiquitin ligase complexes and triaged between degradative and nondegradative fates. The mechanisms that convert modest differences in substrate-ligase interactions into decisive outcomes of ubiquitination are not well understood. Here, we reconstitute membrane protein recognition and ubiquitination in liposomes using purified components from a viral-mediated degradation pathway. We find that substrate-ligase interactions in the membrane directly influence processivity of ubiquitin attachment to modulate polyubiquitination. Unexpectedly, differential processivity alone could not explain the differential fates in cultured cells of degraded and nondegraded clients. Both computational and experimental analyses identified continuous deubiquitination as a prerequisite for maximal substrate discrimination. Deubiquitinases reduce polyubiquitin dwell times preferentially on clients that dissociate more rapidly from the ligase. This explains how small differences in substrate-ligase interaction can be amplified into larger differences in net degradation. These results provide a conceptual framework for substrate discrimination during membrane protein quality control. Membrane protein ubiquitination has been reconstituted with purified factors in vitro Differential ligase interactions alone cannot explain how clients are discriminated Maximal client discrimination requires competing deubiquitination activity Deubiquitinases control the dwell time of a degradation mark on potential clients
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Affiliation(s)
- Zai-Rong Zhang
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 18 Library Drive, Bethesda, MD 20892, USA.
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Strebel K. HIV-1 Vpu - an ion channel in search of a job. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1074-81. [PMID: 23831603 DOI: 10.1016/j.bbamem.2013.06.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 06/18/2013] [Accepted: 06/22/2013] [Indexed: 12/22/2022]
Abstract
Vpu is a small membrane protein encoded by HIV-1 and some SIV isolates. The protein is best known for its ability to degrade CD4 and to enhance the release of progeny virions from infected cells. However, Vpu also promotes host-cell apoptosis by deregulating the NFκB signaling pathway and it assembles into cation-conducting membrane pores. This review summarizes our current understanding of these various functions of Vpu with particular emphasis on recent progress in the Vpu field. This article is part of a Special Issue entitled: Viral Membrane Proteins - Channels for Cellular Networking.
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Affiliation(s)
- Klaus Strebel
- Viral Biochemistry Section, Laboratory of Molecular Microbiology, NIAID, NIH Bldg. 4, Room 310, 4 Center Drive MSC 0460, Bethesda, MD 20892-0460, USA.
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