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Ghanam RH, Eastep GN, Saad JS. Structural Insights into the Mechanism of HIV-1 Tat Secretion from the Plasma Membrane. J Mol Biol 2023; 435:167880. [PMID: 36370804 PMCID: PMC9822876 DOI: 10.1016/j.jmb.2022.167880] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/27/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) trans-activator of transcription (Tat) is a small, intrinsically disordered basic protein that plays diverse roles in the HIV-1 replication cycle, including promotion of efficient viral RNA transcription. Tat is released by infected cells and subsequently absorbed by healthy cells, thereby contributing to HIV-1 pathogenesis including HIV-associated neurocognitive disorder. It has been shown that, in HIV-1-infected primary CD4 T-cells, Tat accumulates at the plasma membrane (PM) for secretion, a mechanism mediated by phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). However, the structural basis for Tat interaction with the PM and thereby secretion is lacking. Herein, we employed NMR and biophysical methods to characterize Tat86 (86 amino acids) interactions with PI(4,5)P2 and lipid nanodiscs (NDs). Our data revealed that Arg49, Lys50 and Lys51 (RKK motif) constitute the PI(4,5)P2 binding site, that Tat86 interaction with lipid NDs is dependent on PI(4,5)P2 and phosphatidylserine (PS), and that the arginine-rich motif (RRQRRR) preferentially interacts with PS. Furthermore, we show that Trp11, previously implicated in Tat secretion, penetrates deeply in the membrane; substitution of Trp11 severely reduced Tat86 interaction with membranes. Deletion of the entire highly basic region and Trp11 completely abolished Tat86 binding to lipid NDs. Our data support a mechanism by which HIV-1 Tat secretion from the PM is mediated by a tripartite signal consisting of binding of the RKK motif to PI(4,5)P2, arginine-rich motif to PS, and penetration of Trp11 in the membrane. Altogether, these findings provide new insights into the molecular requirements for Tat binding to membranes during secretion.
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Affiliation(s)
- Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Gunnar N Eastep
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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Ali A, Mishra R, Kaur H, Chandra Banerjea A. HIV-1 Tat: An update on transcriptional and non-transcriptional functions. Biochimie 2021; 190:24-35. [PMID: 34242726 DOI: 10.1016/j.biochi.2021.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 01/05/2023]
Abstract
Over the past decades, much have been learned about HIV-1 virus and its molecular strategies for pathogenesis. However, HIV-1 still remains an enigmatic virus, particularly because of its unique proteins. Establishment of latency and reactivation is still a puzzling question and various temporal and spatial dynamics between HIV-1 proteins itself have given us new way of thinking about its pathogenesis. HIV-1 replication depends on Tat which is a small unstructured protein and subjected to various post-translational modifications for its myriad of functions. HIV-1 Tat protein modulates the functions of various strategic cellular pathways like proteasomal machinery and inflammatory pathways to aid in HIV-1 pathogenesis. Many of the recent findings have shown that Tat is associated with exosomes, cleared from HIV-1 infected cells through its degradation by diverse routes ranging from lysosomal to proteasomal pathways. HIV-1 Tat was also found to be associated with other HIV-1 proteins including Vpr, Nef, Nucleocapsid (NC) and Rev. Interaction of Tat with Vpr and Nef increases its transactivation function, whereas, interaction of Tat with NC or Rev leads to Tat protein degradation and hence suppression of Tat functions. Research in the recent years has established that Tat is not only important for HIV-1 promoter transactivation and virus replication but also modulating multiple cellular and molecular functions leading to HIV-1 pathogenicity. In this review we discussed various transcriptional and non-transcriptional HIV-1 Tat functions which modulate host cell metabolism during HIV-1 pathogenesis.
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Affiliation(s)
- Amjad Ali
- Virology Lab, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India; Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, 01605, USA.
| | - Ritu Mishra
- Virology Lab, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
| | - Harsimrut Kaur
- Department of Chemistry and Biochemistry, School of Basic Sciences and Research, Sharda University, Knowledge Park III, Greater Noida, Uttar Pradesh, 201310, India.
| | - Akhil Chandra Banerjea
- Virology Lab, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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Labadie T, Sullivan E, Roy P. Multiple Routes of Bluetongue Virus Egress. Microorganisms 2020; 8:E965. [PMID: 32605099 PMCID: PMC7409164 DOI: 10.3390/microorganisms8070965] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/18/2020] [Accepted: 06/25/2020] [Indexed: 12/20/2022] Open
Abstract
Bluetongue virus (BTV) is an arthropod-borne virus infecting livestock. Its frequent emergence in Europe and North America had caused significant agricultural and economic loss. BTV is also of scientific interest as a model to understand the mechanisms underlying non-enveloped virus release from mammalian and insect cells. The BTV particle, which is formed of a complex double-layered capsid, was first considered as a lytic virus that needs to lyse the infected cells for cell to cell transmission. In the last decade, however, a more in-depth focus on the role of the non-structural proteins has led to several examples where BTV particles are also released through different budding mechanisms at the plasma membrane. It is now clear that the non-structural protein NS3 is the main driver of BTV release, via different interactions with both viral and cellular proteins of the cell sorting and exocytosis pathway. In this review, we discuss the most recent advances in the molecular biology of BTV egress and compare the mechanisms that lead to lytic or non-lytic BTV release.
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Affiliation(s)
| | | | - Polly Roy
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London WC1E 7HT, UK; (T.L.); (E.S.)
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Cucchi D, Camacho-Muñoz D, Certo M, Pucino V, Nicolaou A, Mauro C. Fatty acids - from energy substrates to key regulators of cell survival, proliferation and effector function. Cell Stress 2019; 4:9-23. [PMID: 31922096 PMCID: PMC6946016 DOI: 10.15698/cst2020.01.209] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 12/13/2022] Open
Abstract
Recent advances in immunology and cancer research show that fatty acids, their metabolism and their sensing have a crucial role in the biology of many different cell types. Indeed, they are able to affect cellular behaviour with great implications for pathophysiology. Both the catabolic and anabolic pathways of fatty acids present us with a number of enzymes, receptors and agonists/antagonists that are potential therapeutic targets, some of which have already been successfully pursued. Fatty acids can affect the differentiation of immune cells, particularly T cells, as well as their activation and function, with important consequences for the balance between anti- and pro-inflammatory signals in immune diseases, such as rheumatoid arthritis, psoriasis, diabetes, obesity and cardiovascular conditions. In the context of cancer biology, fatty acids mainly provide substrates for energy production, which is of crucial importance to meet the energy demands of these highly proliferating cells. Fatty acids can also be involved in a broader transcriptional programme as they trigger signals necessary for tumorigenesis and can confer to cancer cells the ability to migrate and generate distant metastasis. For these reasons, the study of fatty acids represents a new research direction that can generate detailed insight and provide novel tools for the understanding of immune and cancer cell biology, and, more importantly, support the development of novel, efficient and fine-tuned clinical interventions. Here, we review the recent literature focusing on the involvement of fatty acids in the biology of immune cells, with emphasis on T cells, and cancer cells, from sensing and binding, to metabolism and downstream effects in cell signalling.
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Affiliation(s)
- Danilo Cucchi
- Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Dolores Camacho-Muñoz
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, School of Health sciences, The University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester M13 9PT, UK
| | - Michelangelo Certo
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Mindelsohn Way, Birmingham B15 2WB, UK
| | - Valentina Pucino
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Mindelsohn Way, Birmingham B15 2WB, UK
| | - Anna Nicolaou
- Laboratory for Lipidomics and Lipid Biology, Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, School of Health sciences, The University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester M13 9PT, UK
- Lydia Becker Institute of Immunology and Inflammation, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Oxford Road, Manchester M13 9PT, UK
| | - Claudio Mauro
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Mindelsohn Way, Birmingham B15 2WB, UK
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Mindelsohn Way, Birmingham B15 2WB, UK
- Institute of Metabolism and Systems Research, College of Medical and Dental Sciences, University of Birmingham, Mindelsohn Way, Birmingham B15 2WB, UK
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Chopard C, Tong PBV, Tóth P, Schatz M, Yezid H, Debaisieux S, Mettling C, Gross A, Pugnière M, Tu A, Strub JM, Mesnard JM, Vitale N, Beaumelle B. Cyclophilin A enables specific HIV-1 Tat palmitoylation and accumulation in uninfected cells. Nat Commun 2018; 9:2251. [PMID: 29884859 PMCID: PMC5993824 DOI: 10.1038/s41467-018-04674-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 05/15/2018] [Indexed: 12/21/2022] Open
Abstract
Most HIV-1 Tat is unconventionally secreted by infected cells following Tat interaction with phosphatidylinositol (4,5) bisphosphate (PI(4,5)P2) at the plasma membrane. Extracellular Tat is endocytosed by uninfected cells before escaping from endosomes to reach the cytosol and bind PI(4,5)P2. It is not clear whether and how incoming Tat concentrates in uninfected cells. Here we show that, in uninfected cells, the S-acyl transferase DHHC-20 together with the prolylisomerases cyclophilin A (CypA) and FKBP12 palmitoylate Tat on Cys31 thereby increasing Tat affinity for PI(4,5)P2. In infected cells, CypA is bound by HIV-1 Gag, resulting in its encapsidation and CypA depletion from cells. Because of the lack of this essential cofactor, Tat is not palmitoylated in infected cells but strongly secreted. Hence, Tat palmitoylation specifically takes place in uninfected cells. Moreover, palmitoylation is required for Tat to accumulate at the plasma membrane and affect PI(4,5)P2-dependent membrane traffic such as phagocytosis and neurosecretion. It is not clear whether and how incoming HIV-1 Tat accumulates in uninfected cells. Here, Chopard et al. show that, in uninfected cells, incoming Tat is palmitoylated on Cys31 by DHHC-20, which increases its affinity for PI(4,5)P2 and results in its accumulation at the plasma membrane.
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Affiliation(s)
- Christophe Chopard
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Phuoc Bao Viet Tong
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Petra Tóth
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France.
| | - Malvina Schatz
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Hocine Yezid
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Solène Debaisieux
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Clément Mettling
- IGH, UPR 1142 CNRS, 141 Rue de la Cardonille, 34396, Montpellier, France
| | - Antoine Gross
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Martine Pugnière
- IRCM, INSERM U 1194, 208 Rue des Apothicaires, 34298, Montpellier, France
| | - Annie Tu
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France
| | - Jean-Marc Strub
- CNRS, IPHC UMR 7178, Université de Strasbourg, 67000, Strasbourg, France
| | - Jean-Michel Mesnard
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Nicolas Vitale
- INCI, UPR 3212 CNRS, 5 rue Blaise Pascal, 67084, Strasbourg, France.,INSERM, 75654, Paris Cedex 13, France
| | - Bruno Beaumelle
- IRIM, UMR 9004, Université de Montpellier-CNRS, 1919 Route de Mende, 34293, Montpellier, France.
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