1
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Thapa G, Bhattacharya A, Bhattacharya S. Molecular dynamics investigation of DNA fragments bound to the anti-HIV protein SAMHD1 reveals alterations in allosteric communications. J Mol Graph Model 2024; 129:108748. [PMID: 38452417 DOI: 10.1016/j.jmgm.2024.108748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/09/2024]
Abstract
The sterile alpha motif and histidine-aspartate domain-containing protein 1 (or SAMHD1), a human dNTP-triphosphohydrolase, contributes to HIV-1 restriction in select terminally differentiated cells of the immune system. While the prevailing hypothesis is that the catalytically active form of the protein is an allosterically triggered tetramer, whose HIV-1 restriction properties are attributed to its dNTP - triphosphohydrolase activity, it is also known to bind to ssRNA and ssDNA oligomers. A complete picture of the structure-function relationship of the enzyme is still elusive and the function corresponding to its nucleic acid binding ability is debated. In this in silico study, we investigate the stability, preference and allosteric effects of DNA oligomers bound to SAMHD1. In particular, we compare the binding of DNA and RNA oligomers of the same sequence and also consider the binding of DNA fragments with phosphorothioate bonds in the backbone. The results are compared with the canonical form with the monomers connected by GTP/dATP crossbridges. The simulations indicate that SAMHD1 dimers preferably bind to DNA and RNA oligomers compared to GTP/dATP. However, allosteric communication channels are altered in the nucleic acid acid bound complexes compared to the canonical form. All results are consistent with the hypothesis that the DNA bound form of the protein correspond to an unproductive off-pathway state where the protein is sequestered and not available for dNTP hydrolysis.
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Affiliation(s)
- Gauri Thapa
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India.
| | | | - Swati Bhattacharya
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, 400076, India.
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2
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Acton OJ, Sheppard D, Kunzelmann S, Caswell SJ, Nans A, Burgess AJO, Kelly G, Morris ER, Rosenthal PB, Taylor IA. Platform-directed allostery and quaternary structure dynamics of SAMHD1 catalysis. Nat Commun 2024; 15:3775. [PMID: 38710701 PMCID: PMC11074143 DOI: 10.1038/s41467-024-48237-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 04/25/2024] [Indexed: 05/08/2024] Open
Abstract
SAMHD1 regulates cellular nucleotide homeostasis, controlling dNTP levels by catalysing their hydrolysis into 2'-deoxynucleosides and triphosphate. In differentiated CD4+ macrophage and resting T-cells SAMHD1 activity results in the inhibition of HIV-1 infection through a dNTP blockade. In cancer, SAMHD1 desensitizes cells to nucleoside-analogue chemotherapies. Here we employ time-resolved cryogenic-EM imaging and single-particle analysis to visualise assembly, allostery and catalysis by this multi-subunit enzyme. Our observations reveal how dynamic conformational changes in the SAMHD1 quaternary structure drive the catalytic cycle. We capture five states at high-resolution in a live catalytic reaction, revealing how allosteric activators support assembly of a stable SAMHD1 tetrameric core and how catalysis is driven by the opening and closing of active sites through pairwise coupling of active sites and order-disorder transitions in regulatory domains. This direct visualisation of enzyme catalysis dynamics within an allostery-stabilised platform sets a precedent for mechanistic studies into the regulation of multi-subunit enzymes.
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Affiliation(s)
- Oliver J Acton
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- AstraZeneca, The Discovery Centre, 1 Francis Crick Avenue, Cambridge, CB2 0AA, UK
| | - Devon Sheppard
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Simone Kunzelmann
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Sarah J Caswell
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- AstraZeneca, The Discovery Centre, 1 Francis Crick Avenue, Cambridge, CB2 0AA, UK
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Ailidh J O Burgess
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Geoff Kelly
- The Medical Research Council Biomedical NMR Centre, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Elizabeth R Morris
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
- Department of Biosciences, University of Durham, Durham, DH1 3LE, UK
| | - Peter B Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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3
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McCown C, Yu CH, Ivanov DN. Allosteric substrate activation of SAMHD1 shapes deoxynucleotide triphosphate imbalances by interconnecting the depletion and biosynthesis of different dNTPs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567083. [PMID: 38014186 PMCID: PMC10680743 DOI: 10.1101/2023.11.14.567083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
SAMHD1 is a dNTPase that impedes replication of HIV-1 in myeloid cells and resting T lymphocytes. Here we elucidate the substrate activation mechanism of SAMHD1 that depends on dNTP binding at allosteric sites and the concomitant tetramerization of the enzyme. The study reveals that SAMHD1 activation involves an inactive tetrameric intermediate with partial occupancy of the allosteric sites. The equilibrium between the inactive and active tetrameric states, which is coupled to cooperative binding/dissociation of at least two allosteric dNTP ligands, controls the dNTPase activity of the enzyme, which, in addition, depends on the identity of the dNTPs occupying the four allosteric sites of the active tetramer. We show how such allosteric regulation determines deoxynucleotide triphosphate levels established in the dynamic equilibria between dNTP production and SAMHD1-catalyzed depletion. Notably, the mechanism enables a distinctive functionality of SAMHD1, which we call facilitated dNTP depletion, whereby elevated biosynthesis of some dNTPs results in more efficient depletion of others. The regulatory relationship between the biosynthesis and depletion of different dNTPs sheds light on the emerging role of SAMHD1 in the biology of dNTP homeostasis with implications for HIV/AIDS, innate antiviral immunity, T cell disorders, telomere maintenance and therapeutic efficacy of nucleoside analogs.
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4
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Schüssler M, Schott K, Fuchs NV, Oo A, Zahadi M, Rauch P, Kim B, König R. Gene editing of SAMHD1 in macrophage-like cells reveals complex relationships between SAMHD1 phospho-regulation, HIV-1 restriction, and cellular dNTP levels. mBio 2023; 14:e0225223. [PMID: 37800914 PMCID: PMC10653793 DOI: 10.1128/mbio.02252-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE We introduce BLaER1 cells as an alternative myeloid cell model in combination with CRISPR/Cas9-mediated gene editing to study the influence of sterile α motif and HD domain-containing protein 1 (SAMHD1) T592 phosphorylation on anti-viral restriction and the control of cellular dNTP levels in an endogenous, physiologically relevant context. A proper understanding of the mechanism of the anti-viral function of SAMHD1 will provide attractive strategies aiming at selectively manipulating SAMHD1 without affecting other cellular functions. Even more, our toolkit may inspire further genetic analysis and investigation of restriction factors inhibiting retroviruses and their cellular function and regulation, leading to a deeper understanding of intrinsic anti-viral immunity.
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Affiliation(s)
- Moritz Schüssler
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | | | - Adrian Oo
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
| | - Morssal Zahadi
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Paula Rauch
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Baek Kim
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
- Center for Drug Discovery, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
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5
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Schüssler M, Schott K, Fuchs NV, Oo A, Zahadi M, Rauch P, Kim B, König R. Gene editing of SAMHD1 in macrophage-like cells reveals complex relationships between SAMHD1 phospho-regulation, HIV-1 restriction and cellular dNTP levels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554731. [PMID: 37662193 PMCID: PMC10473771 DOI: 10.1101/2023.08.24.554731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Sterile α motif (SAM) and HD domain-containing protein 1 (SAMHD1) is a dNTP triphosphate triphosphohydrolase (dNTPase) and a potent restriction factor for immunodeficiency virus 1 (HIV-1), active in myeloid and resting CD4+ T cells. The anti-viral activity of SAMHD1 is regulated by dephosphorylation of the residue T592. However, the impact of T592 phosphorylation on dNTPase activity is still under debate. Whether additional cellular functions of SAMHD1 impact anti-viral restriction is not completely understood. We report BLaER1 cells as a novel human macrophage HIV-1 infection model combined with CRISPR/Cas9 knock-in (KI) introducing specific mutations into the SAMHD1 locus to study mutations in a physiological context. Transdifferentiated BLaER1 cells harbor active dephosphorylated SAMHD1 that blocks HIV-1 reporter virus infection. As expected, homozygous T592E mutation, but not T592A, relieved a block to HIV-1 reverse transcription. Co-delivery of VLP-Vpx to SAMHD1 T592E KI mutant cells did not further enhance HIV-1 infection indicating the absence of an additional SAMHD1-mediated antiviral activity independent of T592 de-phosphorylation. T592E KI cells retained dNTP levels similar to WT cells indicating uncoupling of anti-viral and dNTPase activity of SAMHD1. The integrity of the catalytic site in SAMHD1 was critical for anti-viral activity, yet poor correlation of HIV-1 restriction and global cellular dNTP levels was observed in cells harboring catalytic core mutations. Together, we emphasize the complexity of the relationship between HIV-1 restriction, SAMHD1 enzymatic function and T592 phospho-regulation and provide novel tools for investigation in an endogenous and physiological context.
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Affiliation(s)
- Moritz Schüssler
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | | | - Adrian Oo
- Department of Pediatrics, Emory University, Atlanta, USA
| | - Morssal Zahadi
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Paula Rauch
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Baek Kim
- Department of Pediatrics, Emory University, Atlanta, USA
- Center for Drug Discovery, Children’s Healthcare of Atlanta, Atlanta, USA
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
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6
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Bowen NE, Tao S, Cho YJ, Schinazi RF, Kim B. Vpx requires active cellular dNTP biosynthesis to effectively counteract the anti-lentivirus activity of SAMHD1 in macrophages. J Biol Chem 2023; 299:104984. [PMID: 37390988 PMCID: PMC10374972 DOI: 10.1016/j.jbc.2023.104984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023] Open
Abstract
HIV-1 replication in primary monocyte-derived macrophages (MDMs) is kinetically restricted at the reverse transcription step due to the low deoxynucleoside triphosphates (dNTP) pools established by host dNTPase, SAM and HD domain containing protein 1 (SAMHD1). Lentiviruses such as HIV-2 and some Simian immunodeficiency virus counteract this restriction using viral protein X (Vpx), which proteosomally degrades SAMHD1 and elevates intracellular dNTP pools. However, how dNTP pools increase after Vpx degrades SAMHD1 in nondividing MDMs where no active dNTP biosynthesis is expected to exists remains unclear. In this study, we monitored known dNTP biosynthesis machinery during primary human monocyte differentiation to MDMs and unexpectedly found MDMs actively express dNTP biosynthesis enzymes such as ribonucleotide reductase, thymidine kinase 1, and nucleoside-diphosphate kinase. During differentiation from monocytes the expression levels of several biosynthesis enzymes are upregulated, while there is an increase in inactivating SAMHD1 phosphorylation. Correspondingly, we observed significantly lower levels of dNTPs in monocytes compared to MDMs. Without dNTP biosynthesis availability, Vpx failed to elevate dNTPs in monocytes, despite SAMHD1 degradation. These extremely low monocyte dNTP concentrations, which cannot be elevated by Vpx, impaired HIV-1 reverse transcription in a biochemical simulation. Furthermore, Vpx failed to rescue the transduction efficiency of a HIV-1 GFP vector in monocytes. Collectively, these data suggest that MDMs harbor active dNTP biosynthesis and Vpx requires this dNTP biosynthesis to elevate dNTP levels to effectively counteract SAMHD1 and relieve the kinetic block to HIV-1 reverse transcription in MDMs.
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Affiliation(s)
- Nicole E Bowen
- Department of Pediatrics, Center for ViroScience and Cure, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Sijia Tao
- Department of Pediatrics, Center for ViroScience and Cure, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Young-Jae Cho
- Department of Pediatrics, Center for ViroScience and Cure, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Raymond F Schinazi
- Department of Pediatrics, Center for ViroScience and Cure, School of Medicine, Emory University, Atlanta, Georgia, USA; Children's Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Baek Kim
- Department of Pediatrics, Center for ViroScience and Cure, School of Medicine, Emory University, Atlanta, Georgia, USA; Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
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7
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Tsai MHC, Caswell SJ, Morris ER, Mann MC, Pennell S, Kelly G, Groom HCT, Taylor IA, Bishop KN. Attenuation of reverse transcriptase facilitates SAMHD1 restriction of HIV-1 in cycling cells. Retrovirology 2023; 20:5. [PMID: 37127613 PMCID: PMC10150492 DOI: 10.1186/s12977-023-00620-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 04/06/2023] [Indexed: 05/03/2023] Open
Abstract
BACKGROUND SAMHD1 is a deoxynucleotide triphosphohydrolase that restricts replication of HIV-1 in differentiated leucocytes. HIV-1 is not restricted in cycling cells and it has been proposed that this is due to phosphorylation of SAMHD1 at T592 in these cells inactivating the enzymatic activity. To distinguish between theories for how SAMHD1 restricts HIV-1 in differentiated but not cycling cells, we analysed the effects of substitutions at T592 on restriction and dNTP levels in both cycling and differentiated cells as well as tetramer stability and enzymatic activity in vitro. RESULTS We first showed that HIV-1 restriction was not due to SAMHD1 nuclease activity. We then characterised a panel of SAMHD1 T592 mutants and divided them into three classes. We found that a subset of mutants lost their ability to restrict HIV-1 in differentiated cells which generally corresponded with a decrease in triphosphohydrolase activity and/or tetramer stability in vitro. Interestingly, no T592 mutants were able to restrict WT HIV-1 in cycling cells, despite not being regulated by phosphorylation and retaining their ability to hydrolyse dNTPs. Lowering dNTP levels by addition of hydroxyurea did not give rise to restriction. Compellingly however, HIV-1 RT mutants with reduced affinity for dNTPs were significantly restricted by wild-type and T592 mutant SAMHD1 in both cycling U937 cells and Jurkat T-cells. Restriction correlated with reverse transcription levels. CONCLUSIONS Altogether, we found that the amino acid at residue 592 has a strong effect on tetramer formation and, although this is not a simple "on/off" switch, this does correlate with the ability of SAMHD1 to restrict HIV-1 replication in differentiated cells. However, preventing phosphorylation of SAMHD1 and/or lowering dNTP levels by adding hydroxyurea was not enough to restore restriction in cycling cells. Nonetheless, lowering the affinity of HIV-1 RT for dNTPs, showed that restriction is mediated by dNTP levels and we were able to observe for the first time that SAMHD1 is active and capable of inhibiting HIV-1 replication in cycling cells, if the affinity of RT for dNTPs is reduced. This suggests that the very high affinity of HIV-1 RT for dNTPs prevents HIV-1 restriction by SAMHD1 in cycling cells.
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Affiliation(s)
- Ming-Han C Tsai
- Retroviral Replication Laboratory, The Francis Crick Institute, London, UK
- LabGenius, London, UK
| | - Sarah J Caswell
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
- AstraZeneca, Granta Park, Cambridge, UK
| | - Elizabeth R Morris
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
- Department of Biosciences, University of Durham, Durham, UK
| | - Melanie C Mann
- Retroviral Replication Laboratory, The Francis Crick Institute, London, UK
- Sartorius, Ulm, Germany
| | - Simon Pennell
- Structural Biology of DNA-Damage Signalling Laboratory, The Francis Crick Institute, London, UK
- MRC London Institute of Medical Sciences, London, UK
| | - Geoff Kelly
- The Medical Research Council Biomedical NMR Centre, The Francis Crick Institute, London, UK
| | - Harriet C T Groom
- Retroviral Replication Laboratory, The Francis Crick Institute, London, UK
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
| | - Kate N Bishop
- Retroviral Replication Laboratory, The Francis Crick Institute, London, UK.
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8
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Vauthier V, Lasserre A, Morel M, Versapuech M, Berlioz-Torrent C, Zamborlini A, Margottin-Goguet F, Matkovic R. HUSH-mediated HIV silencing is independent of TASOR phosphorylation on threonine 819. Retrovirology 2022; 19:23. [PMID: 36309692 PMCID: PMC9618200 DOI: 10.1186/s12977-022-00610-7] [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] [Received: 05/18/2022] [Accepted: 10/16/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND TASOR, a component of the HUSH repressor epigenetic complex, and SAMHD1, a cellular triphosphohydrolase (dNTPase), are both anti-HIV proteins antagonized by HIV-2/SIVsmm Viral protein X. As a result, the same viral protein is able to relieve two different blocks along the viral life cell cycle, one at the level of reverse transcription, by degrading SAMHD1, the other one at the level of proviral expression, by degrading TASOR. Phosphorylation of SAMHD1 at T592 has been shown to downregulate its antiviral activity. The discovery that T819 in TASOR was lying within a SAMHD1 T592-like motif led us to ask whether TASOR is phosphorylated on this residue and whether this post-translational modification could regulate its repressive activity. RESULTS Using a specific anti-phospho-antibody, we found that TASOR is phosphorylated at T819, especially in cells arrested in early mitosis by nocodazole. We provide evidence that the phosphorylation is conducted by a Cyclin/CDK1 complex, like that of SAMHD1 at T592. While we could not detect TASOR in quiescent CD4 + T cells, TASOR and its phosphorylated form are present in activated primary CD4 + T lymphocytes. In addition, TASOR phosphorylation appears to be independent from TASOR repressive activity. Indeed, on the one hand, nocodazole barely reactivates HIV-1 in the J-Lat A1 HIV-1 latency model despite TASOR T819 phosphorylation. On the other hand, etoposide, a second cell cycle arresting drug, reactivates latent HIV-1, without concomitant TASOR phosphorylation. Furthermore, overexpression of wt TASOR or T819A or T819E similarly represses gene expression driven by an HIV-1-derived LTR promoter. Finally, while TASOR is degraded by HIV-2 Vpx, TASOR phosphorylation is prevented by HIV-1 Vpr, likely as a consequence of HIV-1 Vpr-mediated-G2 arrest. CONCLUSIONS Altogether, we show that TASOR phosphorylation occurs in vivo on T819. This event does not appear to correlate with TASOR-mediated HIV-1 silencing. We speculate that TASOR phosphorylation is related to a role of TASOR during cell cycle progression.
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Affiliation(s)
- Virginie Vauthier
- Université Paris Cité, CNRS, INSERM, Institut Cochin, 22 Rue Méchain, 75014, Paris, France
| | - Angélique Lasserre
- Université Paris Cité, CNRS, INSERM, Institut Cochin, 22 Rue Méchain, 75014, Paris, France
| | - Marina Morel
- Université Paris Cité, CNRS, INSERM, Institut Cochin, 22 Rue Méchain, 75014, Paris, France
| | - Margaux Versapuech
- Université Paris Cité, CNRS, INSERM, Institut Cochin, 22 Rue Méchain, 75014, Paris, France
| | | | - Alessia Zamborlini
- Center for Immunology of Viral, Auto-Immune, Hematological and Bacterial Diseases, Université Paris-Saclay, Inserm, CEA, IMVA-HB/IDMIT), Fontenay-Aux-Roses, France
| | | | - Roy Matkovic
- Université Paris Cité, CNRS, INSERM, Institut Cochin, 22 Rue Méchain, 75014, Paris, France.
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9
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Bowen NE, Oo A, Kim B. Mechanistic Interplay between HIV-1 Reverse Transcriptase Enzyme Kinetics and Host SAMHD1 Protein: Viral Myeloid-Cell Tropism and Genomic Mutagenesis. Viruses 2022; 14:v14081622. [PMID: 35893688 PMCID: PMC9331428 DOI: 10.3390/v14081622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 11/23/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has been the primary interest among studies on antiviral discovery, viral replication kinetics, drug resistance, and viral evolution. Following infection and entry into target cells, the HIV-1 core disassembles, and the viral RT concomitantly converts the viral RNA into double-stranded proviral DNA, which is integrated into the host genome. The successful completion of the viral life cycle highly depends on the enzymatic DNA polymerase activity of RT. Furthermore, HIV-1 RT has long been known as an error-prone DNA polymerase due to its lack of proofreading exonuclease properties. Indeed, the low fidelity of HIV-1 RT has been considered as one of the key factors in the uniquely high rate of mutagenesis of HIV-1, which leads to efficient viral escape from immune and therapeutic antiviral selective pressures. Interestingly, a series of studies on the replication kinetics of HIV-1 in non-dividing myeloid cells and myeloid specific host restriction factor, SAM domain, and HD domain-containing protein, SAMHD1, suggest that the myeloid cell tropism and high rate of mutagenesis of HIV-1 are mechanistically connected. Here, we review not only HIV-1 RT as a key antiviral target, but also potential evolutionary and mechanistic crosstalk among the unique enzymatic features of HIV-1 RT, the replication kinetics of HIV-1, cell tropism, viral genetic mutation, and host SAMHD1 protein.
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Affiliation(s)
- Nicole E. Bowen
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA 30329, USA; (N.E.B.); (A.O.)
| | - Adrian Oo
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA 30329, USA; (N.E.B.); (A.O.)
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA 30329, USA; (N.E.B.); (A.O.)
- Center for Drug Discovery, Children’s Healthcare of Atlanta, Atlanta, GA 30329, USA
- Correspondence:
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10
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Orris B, Huynh KW, Ammirati M, Han S, Bolaños B, Carmody J, Petroski MD, Bosbach B, Shields DJ, Stivers JT. Phosphorylation of SAMHD1 Thr592 increases C-terminal domain dynamics, tetramer dissociation and ssDNA binding kinetics. Nucleic Acids Res 2022; 50:7545-7559. [PMID: 35801923 PMCID: PMC9303311 DOI: 10.1093/nar/gkac573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/24/2022] [Accepted: 07/06/2022] [Indexed: 01/07/2023] Open
Abstract
SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) is driven into its activated tetramer form by binding of GTP activator and dNTP activators/substrates. In addition, the inactive monomeric and dimeric forms of the enzyme bind to single-stranded (ss) nucleic acids. During DNA replication SAMHD1 can be phosphorylated by CDK1 and CDK2 at its C-terminal threonine 592 (pSAMHD1), localizing the enzyme to stalled replication forks (RFs) to promote their restart. Although phosphorylation has only a small effect on the dNTPase activity and ssDNA binding affinity of SAMHD1, perturbation of the native T592 by phosphorylation decreased the thermal stability of tetrameric SAMHD1 and accelerated tetramer dissociation in the absence and presence of ssDNA (∼15-fold). In addition, we found that ssDNA binds competitively with GTP to the A1 site. A full-length SAMHD1 cryo-EM structure revealed substantial dynamics in the C-terminal domain (which contains T592), which could be modulated by phosphorylation. We propose that T592 phosphorylation increases tetramer dynamics and allows invasion of ssDNA into the A1 site and the previously characterized DNA binding surface at the dimer-dimer interface. These features are consistent with rapid and regiospecific inactivation of pSAMHD1 dNTPase at RFs or other sites of free ssDNA in cells.
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Affiliation(s)
- Benjamin Orris
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine 725 North Wolfe Street Baltimore, MD 21205, USA
| | | | | | - Seungil Han
- Medicine Design, Pfizer, Groton, CT 06340, USA
| | - Ben Bolaños
- Oncology Research and Development, Pfizer, San Diego, CA 92121, USA
| | - Jason Carmody
- Oncology Research and Development, Pfizer, San Diego, CA 92121, USA
| | | | - Benedikt Bosbach
- Centers for Therapeutic Innovation (CTI), Pfizer, NY, NY 10016, USA
| | - David J Shields
- Centers for Therapeutic Innovation (CTI), Pfizer, NY, NY 10016, USA
| | - James T Stivers
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine 725 North Wolfe Street Baltimore, MD 21205, USA
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11
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Bowen NE, Temple J, Shepard C, Oo A, Arizaga F, Kapoor-Vazirani P, Persaud M, Yu CH, Kim DH, Schinazi RF, Ivanov DN, Diaz-Griffero F, Yu DS, Xiong Y, Kim B. Structural and functional characterization explains loss of dNTPase activity of the cancer-specific R366C/H mutant SAMHD1 proteins. J Biol Chem 2021; 297:101170. [PMID: 34492268 PMCID: PMC8497992 DOI: 10.1016/j.jbc.2021.101170] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/20/2021] [Accepted: 08/23/2021] [Indexed: 01/09/2023] Open
Abstract
Elevated intracellular levels of dNTPs have been shown to be a biochemical marker of cancer cells. Recently, a series of mutations in the multifunctional dNTP triphosphohydrolase (dNTPase), sterile alpha motif and histidine-aspartate domain-containing protein 1 (SAMHD1), have been reported in various cancers. Here, we investigated the structure and functions of SAMHD1 R366C/H mutants, found in colon cancer and leukemia. Unlike many other cancer-specific mutations, the SAMHD1 R366 mutations do not alter cellular protein levels of the enzyme. However, R366C/H mutant proteins exhibit a loss of dNTPase activity, and their X-ray structures demonstrate the absence of dGTP substrate in their active site, likely because of a loss of interaction with the γ-phosphate of the substrate. The R366C/H mutants failed to reduce intracellular dNTP levels and restrict HIV-1 replication, functions of SAMHD1 that are dependent on the ability of the enzyme to hydrolyze dNTPs. However, these mutants retain dNTPase-independent functions, including mediating dsDNA break repair, interacting with CtIP and cyclin A2, and suppressing innate immune responses. Finally, SAMHD1 degradation in human primary-activated/dividing CD4+ T cells further elevates cellular dNTP levels. This study suggests that the loss of SAMHD1 dNTPase activity induced by R366 mutations can mechanistically contribute to the elevated dNTP levels commonly found in cancer cells.
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Affiliation(s)
- Nicole E Bowen
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Joshua Temple
- Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Caitlin Shepard
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Adrian Oo
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Fidel Arizaga
- Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Priya Kapoor-Vazirani
- Department of Radiation Oncology, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Mirjana Persaud
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Corey H Yu
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Dong-Hyun Kim
- School of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Dmitri N Ivanov
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA
| | - David S Yu
- Department of Radiation Oncology, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, School of Medicine, Yale University, New Haven, Connecticut, USA.
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA; Children's Healthcare of Atlanta, Atlanta, Georgia, USA.
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12
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Batalis S, Rogers LC, Hemphill WO, Mauney CH, Ornelles DA, Hollis T. SAMHD1 Phosphorylation at T592 Regulates Cellular Localization and S-phase Progression. Front Mol Biosci 2021; 8:724870. [PMID: 34513928 PMCID: PMC8426622 DOI: 10.3389/fmolb.2021.724870] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 08/16/2021] [Indexed: 12/02/2022] Open
Abstract
SAMHD1 activity is regulated by a network of mechanisms including phosphorylation, oxidation, oligomerization, and others. Significant questions remain about the effects of phosphorylation on SAMHD1 function and activity. We investigated the effects of a SAMHD1 T592E phosphorylation mimic on its cellular localization, catalytic activity, and cell cycle progression. We found that the SAMHD1 T592E is a catalytically active enzyme that is inhibited by protein oxidation. SAMHD1 T592E is retained in the nucleus at higher levels than the wild-type protein during growth factor-mediated signaling. This nuclear localization protects SAMHD1 from oxidation by cytoplasmic reactive oxygen species. The SAMHD1 T592E phosphomimetic further inhibits the cell cycle S/G2 transition. This has significant implications for SAMHD1 function in regulating innate immunity, antiviral response and DNA replication.
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Affiliation(s)
- Stephanie Batalis
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - LeAnn C Rogers
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Wayne O Hemphill
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Christopher H Mauney
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - David A Ornelles
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC, United States
| | - Thomas Hollis
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC, United States
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13
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Schott K, Majer C, Bulashevska A, Childs L, Schmidt MHH, Rajalingam K, Munder M, König R. SAMHD1 in cancer: curse or cure? J Mol Med (Berl) 2021; 100:351-372. [PMID: 34480199 PMCID: PMC8843919 DOI: 10.1007/s00109-021-02131-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 07/15/2021] [Accepted: 08/12/2021] [Indexed: 12/12/2022]
Abstract
Human sterile α motif and HD domain-containing protein 1 (SAMHD1), originally described as the major cellular deoxyribonucleoside triphosphate triphosphohydrolase (dNTPase) balancing the intracellular deoxynucleotide (dNTP) pool, has come recently into focus of cancer research. As outlined in this review, SAMHD1 has been reported to be mutated in a variety of cancer types and the expression of SAMHD1 is dysregulated in many cancers. Therefore, SAMHD1 is regarded as a tumor suppressor in certain tumors. Moreover, it has been proposed that SAMHD1 might fulfill the requirements of a driver gene in tumor development or might promote a so-called mutator phenotype. Besides its role as a dNTPase, several novel cellular functions of SAMHD1 have come to light only recently, including a role as negative regulator of innate immune responses and as facilitator of DNA end resection during DNA replication and repair. Therefore, SAMHD1 can be placed at the crossroads of various cellular processes. The present review summarizes the negative role of SAMHD1 in chemotherapy sensitivity, highlights reported SAMHD1 mutations found in various cancer types, and aims to discuss functional consequences as well as underlying mechanisms of SAMHD1 dysregulation potentially involved in cancer development.
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Affiliation(s)
- Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Catharina Majer
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Alla Bulashevska
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Liam Childs
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany
| | - Mirko H H Schmidt
- Institute of Anatomy, Medical Faculty Carl Gustav Carus, Technische Universität Dresden School of Medicine, Dresden, Germany
| | - Krishnaraj Rajalingam
- Cell Biology Unit, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- University Cancer Center Mainz, University Medical Center Mainz, Mainz, Germany
| | - Markus Munder
- Third Department of Medicine, University Medical Center, Johannes Gutenberg University, Mainz, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, Langen, Germany.
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14
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Martinat C, Cormier A, Tobaly-Tapiero J, Palmic N, Casartelli N, Mahboubi B, Coggins SA, Buchrieser J, Persaud M, Diaz-Griffero F, Espert L, Bossis G, Lesage P, Schwartz O, Kim B, Margottin-Goguet F, Saïb A, Zamborlini A. SUMOylation of SAMHD1 at Lysine 595 is required for HIV-1 restriction in non-cycling cells. Nat Commun 2021; 12:4582. [PMID: 34321470 PMCID: PMC8319325 DOI: 10.1038/s41467-021-24802-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/05/2021] [Indexed: 02/06/2023] Open
Abstract
SAMHD1 is a cellular triphosphohydrolase (dNTPase) proposed to inhibit HIV-1 reverse transcription in non-cycling immune cells by limiting the supply of the dNTP substrates. Yet, phosphorylation of T592 downregulates SAMHD1 antiviral activity, but not its dNTPase function, implying that additional mechanisms contribute to viral restriction. Here, we show that SAMHD1 is SUMOylated on residue K595, a modification that relies on the presence of a proximal SUMO-interacting motif (SIM). Loss of K595 SUMOylation suppresses the restriction activity of SAMHD1, even in the context of the constitutively active phospho-ablative T592A mutant but has no impact on dNTP depletion. Conversely, the artificial fusion of SUMO2 to a non-SUMOylatable inactive SAMHD1 variant restores its antiviral function, a phenotype that is reversed by the phosphomimetic T592E mutation. Collectively, our observations clearly establish that lack of T592 phosphorylation cannot fully account for the restriction activity of SAMHD1. We find that SUMOylation of K595 is required to stimulate a dNTPase-independent antiviral activity in non-cycling immune cells, an effect that is antagonized by cyclin/CDK-dependent phosphorylation of T592 in cycling cells.
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Affiliation(s)
- Charlotte Martinat
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Arthur Cormier
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Joëlle Tobaly-Tapiero
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Noé Palmic
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Nicoletta Casartelli
- grid.428999.70000 0001 2353 6535Institut Pasteur, Virus and Immunity Unit, CNRS-UMR3569, Paris, France ,grid.511001.4Vaccine Research Institute, Créteil, France
| | - Bijan Mahboubi
- grid.189967.80000 0001 0941 6502Emory School of Medicine, Atlanta, USA
| | - Si’Ana A. Coggins
- grid.189967.80000 0001 0941 6502Emory School of Medicine, Atlanta, USA
| | - Julian Buchrieser
- grid.428999.70000 0001 2353 6535Institut Pasteur, Virus and Immunity Unit, CNRS-UMR3569, Paris, France ,grid.511001.4Vaccine Research Institute, Créteil, France ,grid.4991.50000 0004 1936 8948James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Mirjana Persaud
- grid.251993.50000000121791997Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY USA
| | - Felipe Diaz-Griffero
- grid.251993.50000000121791997Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY USA
| | - Lucile Espert
- grid.503217.2IRIM, University of Montpellier, UMR 9004 CNRS, Montpellier, France
| | - Guillaume Bossis
- grid.429192.50000 0004 0599 0285IGMM, Univ Montpellier, CNRS, Montpellier, France
| | - Pascale Lesage
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Olivier Schwartz
- grid.428999.70000 0001 2353 6535Institut Pasteur, Virus and Immunity Unit, CNRS-UMR3569, Paris, France ,grid.511001.4Vaccine Research Institute, Créteil, France
| | - Baek Kim
- grid.189967.80000 0001 0941 6502Emory School of Medicine, Atlanta, USA
| | | | - Ali Saïb
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France
| | - Alessia Zamborlini
- INSERM U944, CNRS UMR 7212, Genomes & Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France ,grid.457334.2Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
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15
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Wang C, Meng L, Wang J, Zhang K, Duan S, Ren P, Wei Y, Fu X, Yu B, Wu J, Yu X. Role of Intracellular Distribution of Feline and Bovine SAMHD1 Proteins in Lentiviral Restriction. Virol Sin 2021; 36:981-996. [PMID: 33751400 DOI: 10.1007/s12250-021-00351-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/28/2020] [Indexed: 11/28/2022] Open
Abstract
Human SAMHD1 (hSAM) restricts lentiviruses at the reverse transcription step through its dNTP triphosphohydrolase (dNTPase) activity. Besides humans, several mammalian species such as cats and cows that carry their own lentiviruses also express SAMHD1. However, the intracellular distribution of feline and bovine SAMHD1 (fSAM and bSAM) and its significance in their lentiviral restriction function is not known. Here, we demonstrated that fSAM and bSAM were both predominantly localized to the nucleus and nuclear localization signal (11KRPR14)-deleted fSAM and bSAM relocalized to the cytoplasm. Both cytoplasmic fSAM and bSAM retained the antiviral function against different lentiviruses and cytoplasmic fSAM could restrict Vpx-encoding SIV and HIV-2 more efficiently than its wild-type (WT) protein as cytoplasmic hSAM. Further investigation revealed that cytoplasmic fSAM was resistant to Vpx-induced degradation like cytoplasmic hSAM, while cytoplasmic bSAM was not, but they all demonstrated the same in vitro dNTPase activity and all could interact with Vpx as their WT proteins, indicating that cytoplasmic hSAM and fSAM can suppress more SIV and HIV-2 by being less sensitive to Vpx-mediated degradation. Our results suggested that fSAM- and bSAM-mediated lentiviral restriction does not require their nuclear localization and that fSAM shares more common features with hSAM. These findings may provide insights for the establishment of alternative animal models to study SAMHD1 in vivo.
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Affiliation(s)
- Chu Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,The First Hospital and Institute of Immunology, Jilin University, Changchun, 130012, China
| | - Lina Meng
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jialin Wang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Kaikai Zhang
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Sizhu Duan
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Pengyu Ren
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Yingzhe Wei
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Xinyu Fu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Bin Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China.,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China
| | - Jiaxin Wu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
| | - Xianghui Yu
- National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, 130012, China. .,Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, School of Life Sciences, Jilin University, Changchun, 130012, China.
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16
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SAMHD1 … and Viral Ways around It. Viruses 2021; 13:v13030395. [PMID: 33801276 PMCID: PMC7999308 DOI: 10.3390/v13030395] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 12/19/2022] Open
Abstract
The SAM and HD domain-containing protein 1 (SAMHD1) is a dNTP triphosphohydrolase that plays a crucial role for a variety of different cellular functions. Besides balancing intracellular dNTP concentrations, facilitating DNA damage repair, and dampening excessive immune responses, SAMHD1 has been shown to act as a major restriction factor against various virus species. In addition to its well-described activity against retroviruses such as HIV-1, SAMHD1 has been identified to reduce the infectivity of different DNA viruses such as the herpesviruses CMV and EBV, the poxvirus VACV, or the hepadnavirus HBV. While some viruses are efficiently restricted by SAMHD1, others have developed evasion mechanisms that antagonize the antiviral activity of SAMHD1. Within this review, we summarize the different cellular functions of SAMHD1 and highlight the countermeasures viruses have evolved to neutralize the restriction factor SAMHD1.
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17
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Yu CH, Bhattacharya A, Persaud M, Taylor AB, Wang Z, Bulnes-Ramos A, Xu J, Selyutina A, Martinez-Lopez A, Cano K, Demeler B, Kim B, Hardies SC, Diaz-Griffero F, Ivanov DN. Nucleic acid binding by SAMHD1 contributes to the antiretroviral activity and is enhanced by the GpsN modification. Nat Commun 2021; 12:731. [PMID: 33531504 PMCID: PMC7854603 DOI: 10.1038/s41467-021-21023-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 01/08/2021] [Indexed: 12/26/2022] Open
Abstract
SAMHD1 impedes infection of myeloid cells and resting T lymphocytes by retroviruses, and the enzymatic activity of the protein-dephosphorylation of deoxynucleotide triphosphates (dNTPs)-implicates enzymatic dNTP depletion in innate antiviral immunity. Here we show that the allosteric binding sites of the enzyme are plastic and can accommodate oligonucleotides in place of the allosteric activators, GTP and dNTP. SAMHD1 displays a preference for oligonucleotides containing phosphorothioate bonds in the Rp configuration located 3' to G nucleotides (GpsN), the modification pattern that occurs in a mechanism of antiviral defense in prokaryotes. In the presence of GTP and dNTPs, binding of GpsN-containing oligonucleotides promotes formation of a distinct tetramer with mixed occupancy of the allosteric sites. Mutations that impair formation of the mixed-occupancy complex abolish the antiretroviral activity of SAMHD1, but not its ability to deplete dNTPs. The findings link nucleic acid binding to the antiretroviral activity of SAMHD1, shed light on the immunomodulatory effects of synthetic phosphorothioated oligonucleotides and raise questions about the role of nucleic acid phosphorothioation in human innate immunity.
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Affiliation(s)
- Corey H Yu
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Akash Bhattacharya
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Mirjana Persaud
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Alexander B Taylor
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Zhonghua Wang
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Angel Bulnes-Ramos
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Joella Xu
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA, USA
| | - Anastasia Selyutina
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Alicia Martinez-Lopez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kristin Cano
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada.,Department of Chemistry and Biochemistry, University of Montana, Missoula, MT, USA
| | - Baek Kim
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA, USA
| | - Stephen C Hardies
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Dmitri N Ivanov
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA.
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18
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Thapa G, Bhattacharya A, Bhattacharya S. Dimeric Hold States of Anti-HIV Protein SAMHD1 are Redox Tunable. J Chem Inf Model 2020; 60:6377-6391. [PMID: 33135886 DOI: 10.1021/acs.jcim.0c00629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The sterile α motif and histidine-aspartate domain-containing protein 1 (or SAMHD1) is a human protein that restricts HIV-1 in select terminally differentiated cells of the immune system by acting as a triphosphohydrolase, lowering dNTP pools. The functionally active form of the protein has been reported to be a tetramer where adjacent monomers are linked by GTP-Mg+2-dNTP cross-bridges, although some studies have also suggested the existence of a dimeric form of this protein. In this in silico study, we have investigated the stability of SAMHD1 dimeric "hold states" as well as the role of intrachain disulfide bonds. We have found that dimeric-GTP bound SAMHD1 can exist as a viable meso-stable hold state with extensive motion in the C-terminal domain, which is quenched upon tetramer assembly. The redox switch comprised of residues C341, C350, and C522 was found to be linked to changes in the allosteric site, suggesting a mechanism for initiating tetramer disassembly. The disulfide state of the protein dimer (C341-S-S-C350 vs C341-S-S-C522) also plays a role in driving affinities for the allosteric dATP molecules. In sum, our results suggest a model wherein dimeric SAMHD1 exists as a "hold state" in the cytosol, ready to be activated by dATP concentrations, where the "tunability" of this activation is further regulated by the redox state of the enzyme.
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Affiliation(s)
- Gauri Thapa
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Akash Bhattacharya
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, United States
| | - Swati Bhattacharya
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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19
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Kim ET, Roche KL, Kulej K, Spruce LA, Seeholzer SH, Coen DM, Diaz-Griffero F, Murphy EA, Weitzman MD. SAMHD1 Modulates Early Steps during Human Cytomegalovirus Infection by Limiting NF-κB Activation. Cell Rep 2020; 28:434-448.e6. [PMID: 31291579 DOI: 10.1016/j.celrep.2019.06.027] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 03/22/2019] [Accepted: 06/05/2019] [Indexed: 12/14/2022] Open
Abstract
Cellular SAMHD1 inhibits replication of many viruses by limiting intracellular deoxynucleoside triphosphate (dNTP) pools. We investigate the influence of SAMHD1 on human cytomegalovirus (HCMV). During HCMV infection, we observe SAMHD1 induction, accompanied by phosphorylation via viral kinase UL97. SAMHD1 depletion increases HCMV replication in permissive fibroblasts and conditionally permissive myeloid cells. We show this is due to enhanced gene expression from the major immediate-early (MIE) promoter and is independent of dNTP levels. SAMHD1 suppresses innate immune responses by inhibiting nuclear factor κB (NF-κB) activation. We show that SAMHD1 regulates the HCMV MIE promoter through NF-κB activation. Chromatin immunoprecipitation reveals increased RELA and RNA polymerase II on the HCMV MIE promoter in the absence of SAMHD1. Our studies reveal a mechanism of HCMV virus restriction by SAMHD1 and show how SAMHD1 deficiency activates an innate immune pathway that paradoxically results in increased viral replication through transcriptional activation of the HCMV MIE gene promoter.
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Affiliation(s)
- Eui Tae Kim
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Kathryn L Roche
- Department of Translational Medicine, Baruch S. Blumberg Research Institute, Doylestown, PA 18902, USA; Evrys Bio, Pennsylvania Biotechnology Center, Doylestown, PA 18902, USA
| | - Katarzyna Kulej
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Lynn A Spruce
- Protein and Proteomics Core, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Steven H Seeholzer
- Protein and Proteomics Core, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Donald M Coen
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Eain A Murphy
- Department of Translational Medicine, Baruch S. Blumberg Research Institute, Doylestown, PA 18902, USA; Evrys Bio, Pennsylvania Biotechnology Center, Doylestown, PA 18902, USA
| | - Matthew D Weitzman
- Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Division of Protective Immunity and Division of Cancer Pathobiology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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20
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De Meo S, Dell'Oste V, Molfetta R, Tassinari V, Lotti LV, Vespa S, Pignoloni B, Covino DA, Fantuzzi L, Bona R, Zingoni A, Nardone I, Biolatti M, Coscia A, Paolini R, Benkirane M, Edfors F, Sandalova T, Achour A, Hiscott J, Landolfo S, Santoni A, Cerboni C. SAMHD1 phosphorylation and cytoplasmic relocalization after human cytomegalovirus infection limits its antiviral activity. PLoS Pathog 2020; 16:e1008855. [PMID: 32986788 PMCID: PMC7544099 DOI: 10.1371/journal.ppat.1008855] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 10/08/2020] [Accepted: 08/03/2020] [Indexed: 12/16/2022] Open
Abstract
SAMHD1 is a host restriction factor that functions to restrict both retroviruses and DNA viruses, based on its nuclear deoxynucleotide triphosphate (dNTP) hydrolase activity that limits availability of intracellular dNTP pools. In the present study, we demonstrate that SAMHD1 expression was increased following human cytomegalovirus (HCMV) infection, with only a modest effect on infectious virus production. SAMHD1 was rapidly phosphorylated at residue T592 after infection by cellular cyclin-dependent kinases, especially Cdk2, and by the viral kinase pUL97, resulting in a significant fraction of phosho-SAMHD1 being relocalized to the cytoplasm of infected fibroblasts, in association with viral particles and dense bodies. Thus, our findings indicate that HCMV-dependent SAMHD1 cytoplasmic delocalization and inactivation may represent a potential novel mechanism of HCMV evasion from host antiviral restriction activities.
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Affiliation(s)
- Simone De Meo
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Valentina Dell'Oste
- Department of Public Health and Pediatric Sciences, University of Turin, Turin, Italy
| | - Rosa Molfetta
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Valentina Tassinari
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | | | - Simone Vespa
- Laboratory of General Pathology, Center of Aging Science and Translational Medicine (CeSI-MeT) and Department of Medical, Oral and Biotechnological Sciences G. d'Annunzio University, Chieti, Italy
| | - Benedetta Pignoloni
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | | | - Laura Fantuzzi
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Roberta Bona
- National Center for Global Health, Istituto Superiore di Sanità, Rome, Italy
| | - Alessandra Zingoni
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Ilaria Nardone
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Matteo Biolatti
- Department of Public Health and Pediatric Sciences, University of Turin, Turin, Italy
| | - Alessandra Coscia
- Neonatal Unit, Department of Public Health and Pediatric Sciences, University of Turin, Turin, Italy
| | - Rossella Paolini
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Monsef Benkirane
- Institut de Génétique Humaine, Laboratoire de Virologie Moléculaire, CNRS-Université de Montpellier, Montpellier, France
| | - Fredrik Edfors
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Tatyana Sandalova
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Adnane Achour
- Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Division of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - John Hiscott
- Istituto Pasteur Italia-Cenci Bolognetti Foundation, Rome, Italy
| | - Santo Landolfo
- Department of Public Health and Pediatric Sciences, University of Turin, Turin, Italy
| | - Angela Santoni
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
- IRCCS, Neuromed, Pozzilli, Isernia, Italy
| | - Cristina Cerboni
- Department of Molecular Medicine, "Sapienza" University of Rome, Rome, Italy
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21
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SAMHD1 Functions and Human Diseases. Viruses 2020; 12:v12040382. [PMID: 32244340 PMCID: PMC7232136 DOI: 10.3390/v12040382] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/12/2022] Open
Abstract
Deoxynucleoside triphosphate (dNTP) molecules are essential for the replication and maintenance of genomic information in both cells and a variety of viral pathogens. While the process of dNTP biosynthesis by cellular enzymes, such as ribonucleotide reductase (RNR) and thymidine kinase (TK), has been extensively investigated, a negative regulatory mechanism of dNTP pools was recently found to involve sterile alpha motif (SAM) domain and histidine-aspartate (HD) domain-containing protein 1, SAMHD1. When active, dNTP triphosphohydrolase activity of SAMHD1 degrades dNTPs into their 2'-deoxynucleoside (dN) and triphosphate subparts, steadily depleting intercellular dNTP pools. The differential expression levels and activation states of SAMHD1 in various cell types contributes to unique dNTP pools that either aid (i.e., dividing T cells) or restrict (i.e., nondividing macrophages) viral replication that consumes cellular dNTPs. Genetic mutations in SAMHD1 induce a rare inflammatory encephalopathy called Aicardi-Goutières syndrome (AGS), which phenotypically resembles viral infection. Recent publications have identified diverse roles for SAMHD1 in double-stranded break repair, genome stability, and the replication stress response through interferon signaling. Finally, a series of SAMHD1 mutations were also reported in various cancer cell types while why SAMHD1 is mutated in these cancer cells remains to investigated. Here, we reviewed a series of studies that have begun illuminating the highly diverse roles of SAMHD1 in virology, immunology, and cancer biology.
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22
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Mlcochova P, Winstone H, Zuliani-Alvarez L, Gupta RK. TLR4-Mediated Pathway Triggers Interferon-Independent G0 Arrest and Antiviral SAMHD1 Activity in Macrophages. Cell Rep 2020; 30:3972-3980.e5. [PMID: 32209460 PMCID: PMC7109521 DOI: 10.1016/j.celrep.2020.03.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/09/2020] [Accepted: 02/28/2020] [Indexed: 12/20/2022] Open
Abstract
Macrophages exist predominantly in two distinct states, G0 and a G1-like state that is accompanied by phosphorylation of SAMHD1 at T592. Here, we demonstrate that Toll-like receptor 4 (TLR4) activation can potently induce G0 arrest and SAMHD1 antiretroviral activity by an interferon (IFN)-independent pathway. This pathway requires TLR4 engagement with TRIF, but not involvement of TBK1 or IRF3. Exclusive Myd88 activators are unable to trigger G0 arrest or SAMHD1 dephosphorylation, demonstrating this arrest is also Myd88/nuclear factor κB (NF-κB) independent. The G0 arrest is accompanied by p21 upregulation and CDK1 depletion, consistent with the observed SAMHD1 dephosphorylation at T592. Furthermore, we show by SAMHD1 knockdown that the TLR4-activated pathway potently blocks HIV-1 infection in macrophages specifically via SAMHD1. Together, these data demonstrate that macrophages can mobilize an intrinsic cell arrest and anti-viral state by activating TLR4 prior to IFN secretion, thereby highlighting the importance of cell-cycle regulation as a response to pathogen-associated danger signals in macrophages.
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Affiliation(s)
- Petra Mlcochova
- Department of Medicine, University of Cambridge, Cambridge, UK
| | | | | | - Ravindra K Gupta
- Department of Medicine, University of Cambridge, Cambridge, UK; Africa Health Research Institute, Durban, KwaZulu Natal, South Africa.
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23
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Wang Z, Bhattacharya A, White T, Buffone C, McCabe A, Nguyen LA, Shepard CN, Pardo S, Kim B, Weintraub ST, Demeler B, Diaz-Griffero F, Ivanov DN. Functionality of Redox-Active Cysteines Is Required for Restriction of Retroviral Replication by SAMHD1. Cell Rep 2020; 24:815-823. [PMID: 30044979 PMCID: PMC6067006 DOI: 10.1016/j.celrep.2018.06.090] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 05/01/2018] [Accepted: 06/21/2018] [Indexed: 01/04/2023] Open
Abstract
SAMHD1 is a dNTP triphosphohydrolase (dNTPase) that impairs retroviral replication in a subset of noncycling immune cells. Here we show that SAMHD1 is a redox-sensitive enzyme and identify three redox-active cysteines within the protein: C341, C350, and C522. The three cysteines reside near one another and the allosteric nucleotide binding site. Mutations C341S and C522S abolish the ability of SAMHD1 to restrict HIV replication, whereas the C350S mutant remains restriction competent. The C522S mutation makes the protein resistant to inhibition by hydrogen peroxide but has no effect on the tetramerization-dependent dNTPase activity of SAMHD1 in vitro or on the ability of SAMHD1 to deplete cellular dNTPs. Our results reveal that enzymatic activation of SAMHD1 via nucleotide-dependent tetramerization is not sufficient for the establishment of the antiviral state and that retroviral restriction depends on the ability of the protein to undergo redox transformations.
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Affiliation(s)
- Zhonghua Wang
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Akash Bhattacharya
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Tommy White
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Cindy Buffone
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Aine McCabe
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Laura A Nguyen
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
| | - Caitlin N Shepard
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA
| | - Sammy Pardo
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory School of Medicine, Atlanta, GA 30322, USA; School of Pharmacy, Kyunghee University, Seoul, South Korea
| | - Susan T Weintraub
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Borries Demeler
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | - Dmitri N Ivanov
- Department of Biochemistry & Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229, USA.
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24
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Interplay between Intrinsic and Innate Immunity during HIV Infection. Cells 2019; 8:cells8080922. [PMID: 31426525 PMCID: PMC6721663 DOI: 10.3390/cells8080922] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/13/2019] [Accepted: 08/15/2019] [Indexed: 02/06/2023] Open
Abstract
Restriction factors are antiviral components of intrinsic immunity which constitute a first line of defense by blocking different steps of the human immunodeficiency virus (HIV) replication cycle. In immune cells, HIV infection is also sensed by several pattern recognition receptors (PRRs), leading to type I interferon (IFN-I) and inflammatory cytokines production that upregulate antiviral interferon-stimulated genes (ISGs). Several studies suggest a link between these two types of immunity. Indeed, restriction factors, that are generally interferon-inducible, are able to modulate immune responses. This review highlights recent knowledge of the interplay between restriction factors and immunity inducing antiviral defenses. Counteraction of this intrinsic and innate immunity by HIV viral proteins will also be discussed.
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25
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Coggins SA, Holler JM, Kimata JT, Kim DH, Schinazi RF, Kim B. Efficient pre-catalytic conformational change of reverse transcriptases from SAMHD1 non-counteracting primate lentiviruses during dNTP incorporation. Virology 2019; 537:36-44. [PMID: 31442614 DOI: 10.1016/j.virol.2019.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/10/2019] [Accepted: 08/12/2019] [Indexed: 10/26/2022]
Abstract
Unlike HIV-1, HIV-2 and some SIV strains replicate at high dNTP concentrations even in macrophages due to their accessory proteins, Vpx or Vpr, that target SAMHD1 dNTPase for proteasomal degradation. We previously reported that HIV-1 reverse transcriptase (RT) efficiently synthesizes DNA even at low dNTP concentrations because HIV-1 RT displays faster pre-steady state kpol values than SAMHD1 counteracting lentiviral RTs. Here, since the kpol step consists of two sequential sub-steps post dNTP binding, conformational change and chemistry, we investigated which of the two sub-steps RTs from SAMHD1 non-counteracting viruses accelerate in order to complete reverse transcription in the limited dNTP pools found in macrophages. Our study demonstrates that RTs of SAMHD1 non-counteracting lentiviruses have a faster conformational change rate during dNTP incorporation, supporting that these lentiviruses may have evolved to harbor RTs that can efficiently execute the conformational change step in order to circumvent SAMHD1 restriction and dNTP depletion in macrophages.
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Affiliation(s)
- Si'Ana A Coggins
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Jessica M Holler
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Jason T Kimata
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, 77030, Texas, USA
| | - Dong-Hyun Kim
- College of Pharmacy, Kyung Hee University, Seoul, 04427, South Korea
| | - Raymond F Schinazi
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA; College of Pharmacy, Kyung Hee University, Seoul, 04427, South Korea; Children's Healthcare of Atlanta, Atlanta, 30322, USA.
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26
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The missing link: allostery and catalysis in the anti-viral protein SAMHD1. Biochem Soc Trans 2019; 47:1013-1027. [PMID: 31296733 PMCID: PMC7045340 DOI: 10.1042/bst20180348] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 12/11/2022]
Abstract
Vertebrate protein SAMHD1 (sterile-α-motif and HD domain containing protein 1) regulates the cellular dNTP (2′-deoxynucleoside-5′-triphosphate) pool by catalysing the hydrolysis of dNTP into 2′-deoxynucleoside and triphosphate products. As an important regulator of cell proliferation and a key player in dNTP homeostasis, mutations to SAMHD1 are implicated in hypermutated cancers, and germline mutations are associated with Chronic Lymphocytic Leukaemia and the inflammatory disorder Aicardi–Goutières Syndrome. By limiting the supply of dNTPs for viral DNA synthesis, SAMHD1 also restricts the replication of several retroviruses, such as HIV-1, and some DNA viruses in dendritic and myeloid lineage cells and resting T-cells. SAMHD1 activity is regulated throughout the cell cycle, both at the level of protein expression and post-translationally, through phosphorylation. In addition, allosteric regulation further fine-tunes the catalytic activity of SAMHD1, with a nucleotide-activated homotetramer as the catalytically active form of the protein. In cells, GTP and dATP are the likely physiological activators of two adjacent allosteric sites, AL1 (GTP) and AL2 (dATP), that bridge monomer–monomer interfaces to stabilise the protein homotetramer. This review summarises the extensive X-ray crystallographic, biophysical and molecular dynamics experiments that have elucidated important features of allosteric regulation in SAMHD1. We present a comprehensive mechanism detailing the structural and protein dynamics components of the allosteric coupling between nucleotide-induced tetramerization and the catalysis of dNTP hydrolysis by SAMHD1.
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27
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Kong J, Wang MM, He SY, Peng X, Qin XH. Structural characterization and directed modification of Sus scrofa SAMHD1 reveal the mechanism underlying deoxynucleotide regulation. FEBS J 2019; 286:3844-3857. [PMID: 31152619 DOI: 10.1111/febs.14943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 03/12/2019] [Accepted: 05/30/2019] [Indexed: 12/12/2022]
Abstract
Sterile α-motif/histidine-aspartate domain-containing protein 1 (SAMHD1) is an intrinsic antiviral restriction factor known to play a vital role in preventing multiple viral infections and in the control of the cellular deoxynucleoside triphosphate (dNTP) pool. Human and mouse SAMHD1 have both been extensively studied; however, our knowledge on porcine SAMHD1 is limited. Here, we report our findings from comprehensive structural and functional studies on porcine SAMHD1. We determined the crystal structure of porcine SAMHD1 and showed that it forms a symmetric tetramer. Moreover, we modified the deoxynucleotide triphosphohydrolase (dNTPase) activity of SAMHD1 by site-directed mutagenesis based on the crystal structure, and obtained an artificial dimeric enzyme possessing high dNTPase activity. Taken together, our results define the mechanism underlying dNTP regulation and provide a deeper understanding of the regulation of porcine SAMHD1 functions. Directed modification of key residues based on the protein structure enhances the activity of the enzyme, which will be beneficial in the search for new antiviral strategies and for future translational applications.
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Affiliation(s)
- Jia Kong
- School of Chemical Engineering and Technology, Tianjin University, China.,School of Life Sciences, Tianjin University, China
| | - Mei-Mei Wang
- School of Life Sciences, Tianjin University, China
| | - Shuang-Yi He
- School of Life Sciences, Tianjin University, China
| | - Xin Peng
- School of Life Sciences, Tianjin University, China
| | - Xiao-Hong Qin
- School of Life Sciences, Tianjin University, China.,State Key Laboratory of Medicinal Chemical Biology, NanKai University, Tianjin, China
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28
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Buffone C, Kutzner J, Opp S, Martinez-Lopez A, Selyutina A, Coggings SA, Studdard LR, Ding L, Kim B, Spearman P, Schaller T, Diaz-Griffero F. The ability of SAMHD1 to block HIV-1 but not SIV requires expression of MxB. Virology 2019; 531:260-268. [PMID: 30959264 DOI: 10.1016/j.virol.2019.03.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 12/20/2022]
Abstract
SAMHD1 is a human restriction factor known to prevent infection of macrophages, resting CD4+ T cells, and dendritic cells by HIV-1. To test the contribution of MxB to the ability of SAMHD1 to block HIV-1 infection, we created human THP-1 cell lines that were knocked out for expression of MxB, SAMHD1, or both. Interestingly, MxB depletion renders SAMHD1 ineffective against HIV-1 but not SIVmac. We observed similar results in human primary macrophages that were knockdown for the expression of MxB. To understand how MxB assists SAMHD1 restriction of HIV-1, we examined direct interaction between SAMHD1 and MxB in pull-down experiments. In addition, we investigated several properties of SAMHD1 in the absence of MxB expression, including subcellular localization, phosphorylation of the SAMHD1 residue T592, and dNTPs levels. These experiments showed that SAMHD1 restriction of HIV-1 requires expression of MxB.
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Affiliation(s)
- Cindy Buffone
- Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY, 10461, USA
| | - Juliane Kutzner
- University Hospital Heidelberg, Department of Infectious Diseases, Heidelberg, 69120, Germany
| | - Silvana Opp
- Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY, 10461, USA
| | - Alicia Martinez-Lopez
- Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY, 10461, USA
| | - Anastasia Selyutina
- Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY, 10461, USA
| | | | | | - Lingmei Ding
- Cincinnati Children's Hospital, Infectious Diseases, Cincinnati, OH, 45229, USA
| | - Baek Kim
- Emory University, Pediatrics, Atlanta, 30322, Georgia
| | - Paul Spearman
- Cincinnati Children's Hospital, Infectious Diseases, Cincinnati, OH, 45229, USA
| | - Torsten Schaller
- University Hospital Heidelberg, Department of Infectious Diseases, Heidelberg, 69120, Germany
| | - Felipe Diaz-Griffero
- Albert Einstein College of Medicine, Microbiology and Immunology, Bronx, NY, 10461, USA.
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29
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Majer C, Schüssler JM, König R. Intertwined: SAMHD1 cellular functions, restriction, and viral evasion strategies. Med Microbiol Immunol 2019; 208:513-529. [PMID: 30879196 DOI: 10.1007/s00430-019-00593-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 03/08/2019] [Indexed: 01/01/2023]
Abstract
SAMHD1 was initially described for its ability to efficiently restrict HIV-1 replication in myeloid cells and resting CD4+ T cells. However, a growing body of evidence suggests that SAMHD1-mediated restriction is by far not limited to lentiviruses, but seems to be a general concept that applies to most retroviruses and at least a number of DNA viruses. SAMHD1 anti-viral activity was long believed to be solely due to its ability to deplete cellular dNTPs by enzymatic degradation. However, since its discovery, several new functions have been attributed to SAMHD1. It has been demonstrated to bind nucleic acids, to modulate innate immunity, as well as to participate in the DNA damage response and resolution of stalled replication forks. Consequently, it is likely that SAMHD1-mediated anti-viral activity is not or not exclusively mediated through its dNTPase activity. Therefore, in this review, we summarize current knowledge on SAMHD1 cellular functions and systematically discuss how these functions could contribute to the restriction of a broad range of viruses besides retroviruses: herpesviruses, poxviruses and hepatitis B virus. Furthermore, we aim to highlight different ways how viruses counteract SAMHD1-mediated restriction to bypass the SAMHD1-mediated block to viral infection.
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Affiliation(s)
- Catharina Majer
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany
| | | | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany. .,Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA. .,German Center for Infection Research (DZIF), 63225, Langen, Germany. .,Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany.
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30
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Mahboubi B, Gavegnano C, Kim DH, Schinazi RF, Kim B. Host SAMHD1 protein restricts endogenous reverse transcription of HIV-1 in nondividing macrophages. Retrovirology 2018; 15:69. [PMID: 30316304 PMCID: PMC6186296 DOI: 10.1186/s12977-018-0452-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/06/2018] [Indexed: 12/13/2022] Open
Abstract
Background SAM domain and HD domain containing protein 1 (SAMHD1) is a host anti-HIV-1 restriction factor known to suppress viral reverse transcription in nondividing myeloid cells by its dNTP triphosphorylase activity that depletes cellular dNTPs. However, HIV-2 and some SIV strains rapidly replicate in macrophages due to their accessory protein, viral protein X (Vpx), which proteosomally degrades SAMHD1 and elevates dNTP levels. Endogenous reverse transcription (ERT) of retroviruses is the extra-cellular reverse transcription step that partially synthesizes proviral DNAs within cell-free viral particles before the viruses infect new cells. ERT activity utilizes dNTPs co-packaged during budding from the virus-producing cells, and high ERT activity is known to enhance HIV-1 infectivity in nondividing cells. Here, since Vpx elevates cellular dNTP levels in macrophages, we hypothesize that HIV-2 should contain higher ERT activity than HIV-1 in macrophages, and that the Vpx-mediated dNTP elevation should enhance both ERT activity and infectivity of HIV-1 particles produced in macrophages. Results Here, we demonstrate that HIV-2 produced from human primary monocyte derived macrophages displays higher ERT activity than HIV-1 produced from macrophages. Also, HIV-1 particles produced from macrophages treated with virus like particles (VLPs) containing Vpx, Vpx (+), displayed large increases of ERT activity with the enhanced copy numbers of early, middle and late reverse transcription products within the viral particles, compared to the viruses produced from macrophages treated with Vpx (−) VLPs. Furthermore, upon the infection with an equal p24 amount to fresh macrophages, the viruses produced from the Vpx (+) VLP treated macrophages demonstrated higher infectivity than the viruses from the Vpx (−) VLP treated macrophages. Conclusions This finding identifies the viral ERT step as an additional step of HIV-1 replication cycle that SAMHD1 restricts in nondividing myeloid target cells. Electronic supplementary material The online version of this article (10.1186/s12977-018-0452-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bijan Mahboubi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Christina Gavegnano
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Dong-Hyun Kim
- School of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Raymond F Schinazi
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA, 30322, USA. .,School of Pharmacy, Kyung-Hee University, Seoul, South Korea. .,Children's Healthcare of Atlanta, Atlanta, GA, USA.
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31
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USP18 (UBP43) Abrogates p21-Mediated Inhibition of HIV-1. J Virol 2018; 92:JVI.00592-18. [PMID: 30068654 DOI: 10.1128/jvi.00592-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/25/2018] [Indexed: 12/17/2022] Open
Abstract
The host intrinsic innate immune system drives antiviral defenses and viral restriction, which includes the production of soluble factors, such as type I and III interferon (IFN), and activation of restriction factors, including SAMHD1, a deoxynucleoside triphosphohydrolase. Interferon-stimulated gene 15 (ISG15)-specific ubiquitin-like protease 43 (USP18) abrogates IFN signaling pathways. The cyclin-dependent kinase inhibitor p21 (CIP1/WAF1), which is involved in the differentiation and maturation of monocytes, inhibits human immunodeficiency virus type 1 (HIV-1) in macrophages and dendritic cells. p21 inhibition of HIV-1 replication is thought to occur at the reverse transcription step, likely by suppressing cellular deoxynucleoside triphosphate (dNTP) biosynthesis and increasing the amount of antivirally active form of SAMHD1. SAMHD1 strongly inhibits HIV-1 replication in myeloid and resting CD4+ T cells. Here, we studied how USP18 influences HIV-1 replication in human myeloid THP-1 cells. We found that USP18 has the novel ability to inhibit the antiviral function of p21 in differentiated THP-1 cells. USP18 enhanced reverse transcription of HIV-1 by downregulating p21 expression and upregulating intracellular dNTP levels. p21 downregulation by USP18 was associated with the active form of SAMHD1, phosphorylated at T592. USP18 formed a complex with the E3 ubiquitin ligase recognition factor SKP2 (S-phase kinase associated protein 2) and SAMHD1. CRISPR-Cas9 knockout of USP18 increased p21 protein expression and blocked HIV-1 replication. Overall, we propose USP18 as a regulator of p21 antiviral function in differentiated myeloid THP-1 cells.IMPORTANCE Macrophages and dendritic cells are usually the first point of contact with pathogens, including lentiviruses. Host restriction factors, including SAMHD1, mediate the innate immune response against these viruses. However, HIV-1 has evolved to circumvent the innate immune response and establishes disseminated infection. The cyclin-dependent kinase inhibitor p21, which is involved in differentiation and maturation of monocytes, blocks HIV-1 replication at the reverse transcription step. p21 is thought to suppress key enzymes involved in dNTP biosynthesis and activates SAMHD1 antiviral function. We report here that the human USP18 protein is a novel factor potentially contributing to HIV replication by blocking the antiviral function of p21 in differentiated human myeloid cells. USP18 downregulates p21 protein expression, which correlates with upregulated intracellular dNTP levels and the antiviral inactive form of SAMHD1. Depletion of USP18 stabilizes p21 protein expression, which correlates with dephosphorylated SAMHD1 and a block to HIV-1 replication.
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Martinez-Lopez A, Martin-Fernandez M, Buta S, Kim B, Bogunovic D, Diaz-Griffero F. SAMHD1 deficient human monocytes autonomously trigger type I interferon. Mol Immunol 2018; 101:450-460. [PMID: 30099227 DOI: 10.1016/j.molimm.2018.08.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/24/2018] [Accepted: 08/02/2018] [Indexed: 01/04/2023]
Abstract
Germline mutations in the human SAMHD1 gene cause the development of Aicardi-Goutières Syndrome (AGS), with a dominant feature being increased systemic type I interferon(IFN) production. Here we tested the state of type I IFN induction and response to, in SAMHD1 knockout (KO) human monocytic cells. SAMHD1 KO cells exhibited spontaneous transcription and translation of IFN-β and subsequent interferon-stimulated genes (ISGs) as compared to parental wild-type cells. This elevation of IFN-β and ISGs was abrogated via inhibition of the TBK1-IRF3 pathway in the SAMHD1 KO cells. In agreement, we found that SAMHD1 KO cells present high levels of phosphorylated TBK1 when compared to control cells. Moreover, addition of blocking antibody against type I IFN also reversed elevation of ISGs. These experiments suggested that SAMHD1 KO cells are persistently auto-stimulating the TBK1-IRF3 pathway, leading to an enhanced production of type I IFN and subsequent self-induction of ISGs.
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Affiliation(s)
- Alicia Martinez-Lopez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, United States
| | - Marta Martin-Fernandez
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Sofija Buta
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Baek Kim
- Department of Pediatrics, Emory University, Atlanta, GA 30322, United States
| | - Dusan Bogunovic
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, United States.
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33
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Tramentozzi E, Ferraro P, Hossain M, Stillman B, Bianchi V, Pontarin G. The dNTP triphosphohydrolase activity of SAMHD1 persists during S-phase when the enzyme is phosphorylated at T592. Cell Cycle 2018; 17:1102-1114. [PMID: 30039733 PMCID: PMC6110608 DOI: 10.1080/15384101.2018.1480216] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 06/01/2018] [Accepted: 05/16/2018] [Indexed: 01/31/2023] Open
Abstract
SAMHD1 is the major catabolic enzyme regulating the intracellular concentrations of DNA precursors (dNTPs). The S-phase kinase CDK2-cyclinA phosphorylates SAMHD1 at Thr-592. How this modification affects SAMHD1 function is highly debated. We investigated the role of endogenous SAMHD1 phosphorylation during the cell cycle. Thr-592 phosphorylation occurs first at the G1/S border and is removed during mitotic exit parallel with Thr-phosphorylations of most CDK1 targets. Differential sensitivity to the phosphatase inhibitor okadaic acid suggested different involvement of the PP1 and PP2 families dependent upon the time of the cell cycle. SAMHD1 turn-over indicates that Thr-592 phosphorylation does not cause rapid protein degradation. Furthermore, SAMHD1 influenced the size of the four dNTP pools independently of its phosphorylation. Our findings reveal that SAMHD1 is active during the entire cell cycle and performs an important regulatory role during S-phase by contributing with ribonucleotide reductase to maintain dNTP pool balance for proper DNA replication.
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Affiliation(s)
| | - Paola Ferraro
- Department of Biology, University of Padova, Padova, Italy
| | - Manzar Hossain
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Bruce Stillman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Vera Bianchi
- Department of Biology, University of Padova, Padova, Italy
| | - Giovanna Pontarin
- Department of Biology, University of Padova, Padova, Italy
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
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34
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Schott K, Fuchs NV, Derua R, Mahboubi B, Schnellbächer E, Seifried J, Tondera C, Schmitz H, Shepard C, Brandariz-Nuñez A, Diaz-Griffero F, Reuter A, Kim B, Janssens V, König R. Dephosphorylation of the HIV-1 restriction factor SAMHD1 is mediated by PP2A-B55α holoenzymes during mitotic exit. Nat Commun 2018; 9:2227. [PMID: 29884836 PMCID: PMC5993806 DOI: 10.1038/s41467-018-04671-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 05/15/2018] [Indexed: 12/20/2022] Open
Abstract
SAMHD1 is a critical restriction factor for HIV-1 in non-cycling cells and its antiviral activity is regulated by T592 phosphorylation. Here, we show that SAMHD1 dephosphorylation at T592 is controlled during the cell cycle, occurring during M/G1 transition in proliferating cells. Using several complementary proteomics and biochemical approaches, we identify the phosphatase PP2A-B55α responsible for rendering SAMHD1 antivirally active. SAMHD1 is specifically targeted by PP2A-B55α holoenzymes during mitotic exit, in line with observations that PP2A-B55α is a key mitotic exit phosphatase in mammalian cells. Strikingly, as HeLa or activated primary CD4+ T cells enter the G1 phase, pronounced reduction of RT products is observed upon HIV-1 infection dependent on the presence of dephosphorylated SAMHD1. Moreover, PP2A controls SAMHD1 pT592 level in non-cycling monocyte-derived macrophages (MDMs). Thus, the PP2A-B55α holoenzyme is a key regulator to switch on the antiviral activity of SAMHD1.
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Affiliation(s)
- Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Rita Derua
- Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, 3000, Leuven, Belgium.,Facility for Systems Biology based Mass Spectrometry (SYBIOMA), KU Leuven, 3000, Leuven, Belgium
| | - Bijan Mahboubi
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | | | - Janna Seifried
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Christiane Tondera
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Heike Schmitz
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Caitlin Shepard
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Alberto Brandariz-Nuñez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Andreas Reuter
- Division of Allergology, Paul-Ehrlich-Institut, 63225, Langen, Germany
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory University, Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA.,Department of Pharmacy, Kyung-Hee University, 2447, Seoul, South Korea
| | - Veerle Janssens
- Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, 3000, Leuven, Belgium
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institut, 63225, Langen, Germany. .,Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA. .,German Center for Infection Research (DZIF), 63225, Langen, Germany.
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35
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Mauney CH, Hollis T. SAMHD1: Recurring roles in cell cycle, viral restriction, cancer, and innate immunity. Autoimmunity 2018; 51:96-110. [PMID: 29583030 PMCID: PMC6117824 DOI: 10.1080/08916934.2018.1454912] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/16/2018] [Indexed: 12/24/2022]
Abstract
Sterile alpha motif and histidine-aspartic acid domain-containing protein 1 (SAMHD1) is a deoxynucleotide triphosphate (dNTP) hydrolase that plays an important role in the homeostatic balance of cellular dNTPs. Its emerging role as an effector of innate immunity is affirmed by mutations in the SAMHD1 gene that cause the severe autoimmune disease, Aicardi-Goutieres syndrome (AGS) and that are linked to cancer. Additionally, SAMHD1 functions as a restriction factor for retroviruses, such as HIV. Here, we review the current biochemical and biological properties of the enzyme including its structure, activity, and regulation by post-translational modifications in the context of its cellular function. We outline open questions regarding the biology of SAMHD1 whose answers will be important for understanding its function as a regulator of cell cycle progression, genomic integrity, and in autoimmunity.
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Affiliation(s)
- Christopher H Mauney
- a Department of Biochemistry , Center for Structural Biology, Wake Forest School of Medicine , Winston Salem , NC , USA
| | - Thomas Hollis
- a Department of Biochemistry , Center for Structural Biology, Wake Forest School of Medicine , Winston Salem , NC , USA
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36
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Herrmann A, Wittmann S, Thomas D, Shepard CN, Kim B, Ferreirós N, Gramberg T. The SAMHD1-mediated block of LINE-1 retroelements is regulated by phosphorylation. Mob DNA 2018; 9:11. [PMID: 29610582 PMCID: PMC5872582 DOI: 10.1186/s13100-018-0116-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/19/2018] [Indexed: 12/22/2022] Open
Abstract
Background The restriction factor SAMHD1 regulates intracellular nucleotide level by degrading dNTPs and blocks the replication of retroviruses and DNA viruses in non-cycling cells, like macrophages or dendritic cells. In patients, inactivating mutations in samhd1 are associated with the autoimmune disease Aicardi-Goutières Syndrome (AGS). The accumulation of intracellular nucleic acids derived from endogenous retroelements thriving in the absence of SAMHD1 has been discussed as potential trigger of the autoimmune reaction. In vitro, SAMHD1 has been found to restrict endogenous retroelements, like LINE-1 elements (L1). The mechanism, however, by which SAMHD1 blocks endogenous retroelements, is still unclear. Results Here, we show that SAMHD1 inhibits the replication of L1 and other endogenous retroelements in cycling cells. By applying GFP- and neomycin-based reporter assays we found that the anti-L1 activity of SAMHD1 is regulated by phosphorylation at threonine 592 (T592). Similar to the block of HIV, the cofactor binding site and the enzymatic active HD domain of SAMHD1 proofed to be essential for restriction of L1 elements. However, phosphorylation at T592 did not correlate with the dNTP hydrolase activity of SAMHD1 in cycling 293T cells suggesting an alternative mechanism of regulation. Interestingly, we found that SAMHD1 binds to ORF2 protein of L1 and that this interaction is regulated by T592 phosphorylation. Together with the finding that the block is also active in cycling cells, our results suggest that the SAMHD1-mediated inhibition of L1 is similar but not identical to HIV restriction. Conclusion Our findings show conclusively that SAMHD1 restricts the replication of endogenous retroelements in vitro. The results suggest that SAMHD1 is important for maintaining genome integrity and support the idea of an enhanced replication of endogenous retroelements in the absence of SAMHD1 in vivo, potentially triggering autoimmune diseases like AGS. Our analysis also contributes to the better understanding of the activities of SAMHD1 in antiviral defense and nucleotide metabolism. The finding that the phosphorylation of SAMHD1 at T592 regulates its activity against retroelements but not necessarily intracellular dNTP level suggests that the dNTP hydrolase activity might not be the only function of SAMHD1 important for its antiviral activity and for controlling autoimmunity. Electronic supplementary material The online version of this article (10.1186/s13100-018-0116-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alexandra Herrmann
- 1Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany
| | - Sabine Wittmann
- 1Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany
| | - Dominique Thomas
- 2pharmazentrum frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe-University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Caitlin N Shepard
- 3Center for Drug Discovery, Department of Pediatrics, Emory Center for AIDS Research, Emory University, Children's Healthcare of Atlanta, Atlanta, GA 30322 USA
| | - Baek Kim
- 3Center for Drug Discovery, Department of Pediatrics, Emory Center for AIDS Research, Emory University, Children's Healthcare of Atlanta, Atlanta, GA 30322 USA.,4College of Pharmacy, Kyung-Hee University, Seoul, South Korea
| | - Nerea Ferreirós
- 2pharmazentrum frankfurt/ZAFES, Institute of Clinical Pharmacology, Goethe-University, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
| | - Thomas Gramberg
- 1Institute of Clinical and Molecular Virology, Friedrich-Alexander University Erlangen-Nürnberg, Schlossgarten 4, 91054 Erlangen, Germany
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37
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A Cyclin-Binding Motif in Human SAMHD1 Is Required for Its HIV-1 Restriction, dNTPase Activity, Tetramer Formation, and Efficient Phosphorylation. J Virol 2018; 92:JVI.01787-17. [PMID: 29321329 DOI: 10.1128/jvi.01787-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) regulates intracellular deoxynucleoside triphosphate (dNTP) levels and functions as a retroviral restriction factor through its dNTP triphosphohydrolase (dNTPase) activity. Human SAMHD1 interacts with cell cycle regulatory proteins cyclin A2, cyclin-dependent kinase 1 (CDK1), and CDK2. This interaction mediates phosphorylation of SAMHD1 at threonine 592 (T592), which negatively regulates HIV-1 restriction. We previously reported that the interaction is mediated, at least in part, through a cyclin-binding motif (RXL, amino acids [aa] 451 to 453). To understand the role of the RXL motif in regulating SAMHD1 activity, we performed structural and functional analyses of RXL mutants and the effect on HIV-1 restriction. We found that the RXL mutation (R451A and L453A, termed RL/AA) disrupted SAMHD1 tetramer formation and abolished its dNTPase activity in vitro and in cells. Compared to wild-type (WT) SAMHD1, the RL/AA mutant failed to restrict HIV-1 infection and had reduced binding to cyclin A2. WT SAMHD1 and RL/AA mutant proteins were degraded by Vpx from HIV-2 but were not spontaneously ubiquitinated in the absence of Vpx. Analysis of proteasomal and autophagy degradation revealed that WT and RL/AA SAMHD1 protein levels were enhanced only when both pathways of degradation were simultaneously inhibited. Our results demonstrate that the RXL motif of human SAMHD1 is required for its HIV-1 restriction, tetramer formation, dNTPase activity, and efficient phosphorylation at T592. These findings identify a new functional domain of SAMHD1 important for its structural integrity, enzyme activity, phosphorylation, and HIV-1 restriction.IMPORTANCE SAMHD1 is the first mammalian dNTPase identified as a restriction factor that inhibits HIV-1 replication by decreasing the intracellular dNTP pool in nondividing cells, although the critical mechanisms regulating SAMHD1 function remain unclear. We previously reported that mutations of a cyclin-binding RXL motif in human SAMHD1 significantly affect protein expression levels, half-life, nuclear localization, and phosphorylation, suggesting an important role of this motif in modulating SAMHD1 functions in cells. To further understand the significance and mechanisms of the RXL motif in regulating SAMHD1 activity, we performed structural and functional analyses of the RXL motif mutation and its effect on HIV-1 restriction. Our results indicate that the RXL motif is critical for tetramer formation, dNTPase activity, and HIV-1 restriction. These findings help us understand SAMHD1 interactions with other host proteins and the mechanisms regulating SAMHD1 structure and functions in cells.
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38
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Mlcochova P, Caswell SJ, Taylor IA, Towers GJ, Gupta RK. DNA damage induced by topoisomerase inhibitors activates SAMHD1 and blocks HIV-1 infection of macrophages. EMBO J 2018; 37:50-62. [PMID: 29084722 PMCID: PMC5753034 DOI: 10.15252/embj.201796880] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 09/19/2017] [Accepted: 09/22/2017] [Indexed: 12/15/2022] Open
Abstract
We report that DNA damage induced by topoisomerase inhibitors, including etoposide (ETO), results in a potent block to HIV-1 infection in human monocyte-derived macrophages (MDM). SAMHD1 suppresses viral reverse transcription (RT) through depletion of cellular dNTPs but is naturally switched off by phosphorylation in a subpopulation of MDM found in a G1-like state. We report that SAMHD1 was activated by dephosphorylation following ETO treatment, along with loss of expression of MCM2 and CDK1, and reduction in dNTP levels. Suppression of infection occurred after completion of viral DNA synthesis, at the step of 2LTR circle and provirus formation. The ETO-induced block was completely rescued by depletion of SAMHD1 in MDM Concordantly, infection by HIV-2 and SIVsm encoding the SAMHD1 antagonist Vpx was insensitive to ETO treatment. The mechanism of DNA damage-induced blockade of HIV-1 infection involved activation of p53, p21, decrease in CDK1 expression, and SAMHD1 dephosphorylation. Therefore, topoisomerase inhibitors regulate SAMHD1 and HIV permissivity at a post-RT step, revealing a mechanism by which the HIV-1 reservoir may be limited by chemotherapeutic drugs.
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Affiliation(s)
| | - Sarah J Caswell
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
| | - Ian A Taylor
- Macromolecular Structure Laboratory, The Francis Crick Institute, London, UK
| | | | - Ravindra K Gupta
- Division of Infection and Immunity, UCL, London, UK
- Africa Health Research Institute, Durban, KwaZulu Natal, South Africa
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Rocha-Perugini V, Suárez H, Álvarez S, López-Martín S, Lenzi GM, Vences-Catalán F, Levy S, Kim B, Muñoz-Fernández MA, Sánchez-Madrid F, Yáñez-Mó M. CD81 association with SAMHD1 enhances HIV-1 reverse transcription by increasing dNTP levels. Nat Microbiol 2017; 2:1513-1522. [PMID: 28871089 PMCID: PMC5660623 DOI: 10.1038/s41564-017-0019-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 08/01/2017] [Indexed: 12/15/2022]
Abstract
In this study, we report that the tetraspanin CD81 enhances human immunodeficiency virus (HIV)-1 reverse transcription in HIV-1-infected cells. This is enabled by the direct interaction of CD81 with the deoxynucleoside triphosphate phosphohydrolase SAMHD1. This interaction prevents endosomal accumulation and favours the proteasome-dependent degradation of SAMHD1. Consequently, CD81 depletion results in SAMHD1 increased expression, decreasing the availability of deoxynucleoside triphosphates (dNTP) and thus HIV-1 reverse transcription. Conversely, CD81 overexpression, but not the expression of a CD81 carboxy (C)-terminal deletion mutant, increases cellular dNTP content and HIV-1 reverse transcription. Our results demonstrate that the interaction of CD81 with SAMHD1 controls the metabolic rate of HIV-1 replication by tuning the availability of building blocks for reverse transcription, namely dNTPs. Together with its role in HIV-1 entry and budding into host cells, the data herein indicate that HIV-1 uses CD81 as a rheostat that controls different stages of the infection.
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Affiliation(s)
- Vera Rocha-Perugini
- Servicio de Inmunología, Hospital de la Princesa, Instituto de Investigación Sanitaria La Princesa (IIS-IP), Madrid, 28006, Spain
- Vascular Pathophysiology Research Area, Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, 28029, Spain
| | - Henar Suárez
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria La Princesa (IIS-IP), Centro de Biología Molecular Severo Ochoa, Madrid, 28049, Spain
| | - Susana Álvarez
- Servicio de Inmunobiología Molecular del Hospital Universitario Gregorio Marañón, Madrid, 28007, Spain
| | - Soraya López-Martín
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria La Princesa (IIS-IP), Centro de Biología Molecular Severo Ochoa, Madrid, 28049, Spain
| | - Gina M Lenzi
- Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30332, USA
| | - Felipe Vences-Catalán
- Division of Oncology, Center for Clinical Sciences Research, Stanford University, Stanford, CA, 94305-5151, USA
| | - Shoshana Levy
- Division of Oncology, Center for Clinical Sciences Research, Stanford University, Stanford, CA, 94305-5151, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30332, USA
| | - María A Muñoz-Fernández
- Servicio de Inmunobiología Molecular del Hospital Universitario Gregorio Marañón, Madrid, 28007, Spain
| | - Francisco Sánchez-Madrid
- Servicio de Inmunología, Hospital de la Princesa, Instituto de Investigación Sanitaria La Princesa (IIS-IP), Madrid, 28006, Spain
- Vascular Pathophysiology Research Area, Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, 28029, Spain
- CIBER Cardiovascular, Madrid, Spain
| | - Maria Yáñez-Mó
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria La Princesa (IIS-IP), Centro de Biología Molecular Severo Ochoa, Madrid, 28049, Spain.
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Patra KK, Bhattacharya A, Bhattacharya S. Allosteric Signal Transduction in HIV-1 Restriction Factor SAMHD1 Proceeds via Reciprocal Handshake across Monomers. J Chem Inf Model 2017; 57:2523-2538. [PMID: 28956603 DOI: 10.1021/acs.jcim.7b00279] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The sterile alpha motif and histidine-aspartate domain-containing protein 1 (or SAMHD1), a human dNTP-triphosphohydrolase, contributes to HIV-1 restriction in select terminally differentiated cells of the immune system. The catalytically active form of the protein is an allosterically triggered tetramer, whose HIV-1 restriction properties are attributed to its dNTP-triphosphohydrolase activity. The tetramer itself is assembled by a GTP/dNTP combination. This enzyme uses the strategy of deoxynucleotide starvation, which is thought to prevent effective reverse transcription of the retroviral genome-hence, restricting HIV-1 propagation. HIV-2 and SIV have evolved defenses against SAMHD1, underscoring its role in restriction. Previous studies have provided high-resolution structures of GTP/dNTP-bound enzyme complexes but have not been able to provide information on dynamics. In this study, we have used correlation network analysis along with MD techniques to study the flow of allosteric information across the active complex. We have found evidence of a reciprocal allosteric "handshake" occurring across monomeric units. We have also uncovered a short linker region as the nexus for funnelling the regulatory signal from phosphorylation at T592 from the surface to the interior core of the protein.
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Affiliation(s)
- Kajwal Kumar Patra
- Department of Physics, Indian Institute of Technology Guwahati , Guwahati, Assam, India 781039
| | - Akash Bhattacharya
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio , San Antonio, Texas 78229-3900, United States
| | - Swati Bhattacharya
- Department of Physics, Indian Institute of Technology Guwahati , Guwahati, Assam, India 781039.,Department of Chemical Engineering, Indian Institute of Technology Bombay , Mumbai, India 400076
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Herold N, Rudd SG, Sanjiv K, Kutzner J, Myrberg IH, Paulin CBJ, Olsen TK, Helleday T, Henter JI, Schaller T. With me or against me: Tumor suppressor and drug resistance activities of SAMHD1. Exp Hematol 2017; 52:32-39. [PMID: 28502830 DOI: 10.1016/j.exphem.2017.05.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 04/29/2017] [Accepted: 05/02/2017] [Indexed: 01/04/2023]
Abstract
Sterile alpha motif and histidine/aspartic acid domain-containing protein 1 (SAMHD1) is a (deoxy)guanosine triphosphate (dGTP/GTP)-activated deoxyribonucleoside triphosphate (dNTP) triphosphohydrolase involved in cellular dNTP homoeostasis. Mutations in SAMHD1 have been associated with the hyperinflammatory disease Aicardi-Goutières syndrome (AGS). SAMHD1 also limits cells' permissiveness to infection with diverse viruses, including human immunodeficiency virus (HIV-1), and controls endogenous retroviruses. Increasing evidence supports the role of SAMHD1 as a tumor suppressor. However, SAMHD1 also can act as a resistance factor to nucleoside-based chemotherapies by hydrolyzing their active triphosphate metabolites, thereby reducing response of various malignancies to these anticancer drugs. Hence, informed cancer therapies must take into account the ambiguous properties of SAMHD1 as both an inhibitor of uncontrolled proliferation and a resistance factor limiting the efficacy of anticancer treatments. Here, we provide evidence that SAMHD1 is a double-edged sword for patients with acute myelogenous leukemia (AML). Our time-dependent analyses of The Cancer Genome Atlas (TCGA) AML cohort indicate that high expression of SAMHD1, even though it critically limits the efficacy of high-dose ara-C therapy, might be associated with more favorable disease progression.
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Affiliation(s)
- Nikolas Herold
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden; Theme of Children's and Women's Health, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden.
| | - Sean G Rudd
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kumar Sanjiv
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Juliane Kutzner
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Ida Hed Myrberg
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Cynthia B J Paulin
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Thale Kristin Olsen
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Helleday
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Jan-Inge Henter
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden; Theme of Children's and Women's Health, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Torsten Schaller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.
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42
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White TE, Brandariz-Nuñez A, Martinez-Lopez A, Knowlton C, Lenzi G, Kim B, Ivanov D, Diaz-Griffero F. A SAMHD1 mutation associated with Aicardi-Goutières syndrome uncouples the ability of SAMHD1 to restrict HIV-1 from its ability to downmodulate type I interferon in humans. Hum Mutat 2017; 38:658-668. [PMID: 28229507 DOI: 10.1002/humu.23201] [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] [Received: 08/04/2016] [Revised: 02/09/2017] [Accepted: 02/19/2017] [Indexed: 12/23/2022]
Abstract
Mutations in the human SAMHD1 gene are known to correlate with the development of the Aicardi-Goutières syndrome (AGS), which is an inflammatory encephalopathy that exhibits neurological dysfunction characterized by increased production of type I interferon (IFN); this evidence has led to the concept that the SAMHD1 protein negatively regulates the type I IFN response. Additionally, the SAMHD1 protein has been shown to prevent efficient HIV-1 infection of macrophages, dendritic cells, and resting CD4+ T cells. To gain insights on the SAMHD1 molecular determinants that are responsible for the deregulated production of type I IFN, we explored the biochemical, cellular, and antiviral properties of human SAMHD1 mutants known to correlate with the development of AGS. Most of the studied SAMHD1 AGS mutants exhibit defects in the ability to oligomerize, decrease the levels of cellular deoxynucleotide triphosphates in human cells, localize exclusively to the nucleus, and restrict HIV-1 infection. At least half of the tested variants preserved the ability to be degraded by the lentiviral protein Vpx, and all of them interacted with RNA. Our investigations revealed that the SAMHD1 AGS variant p.G209S preserve all tested biochemical, cellular, and antiviral properties, suggesting that this residue is a determinant for the ability of SAMHD1 to negatively regulate the type I IFN response in human patients with AGS. Overall, our work genetically separated the ability of SAMHD1 to negatively regulate the type I IFN response from its ability to restrict HIV-1.
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Affiliation(s)
- Tommy E White
- Department of Microbiology and Immunology, Albert Einstein College of Medicine Bronx, New York
| | - Alberto Brandariz-Nuñez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine Bronx, New York
| | - Alicia Martinez-Lopez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine Bronx, New York
| | | | - Gina Lenzi
- Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Baek Kim
- Department of Pediatrics, Emory University, Atlanta, Georgia
| | - Dmitri Ivanov
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine Bronx, New York
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43
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Patra KK, Bhattacharya A, Bhattacharya S. Uncovering allostery and regulation in SAMHD1 through molecular dynamics simulations. Proteins 2017; 85:1266-1275. [PMID: 28321930 DOI: 10.1002/prot.25287] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/03/2017] [Accepted: 03/14/2017] [Indexed: 11/09/2022]
Abstract
The human sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a retroviral restriction factor in myeloid cells and non-cycling CD4+ T cells, a feature imputed to its phosphohydrolase activity-the enzyme depletes the cellular dNTP levels inhibiting reverse transcription. The functionally active form of SAMHD1 is an allosterically triggered tetramer which utilizes GTP-Mg+2 -dNTP cross bridges to link and stabilize adjacent monomers. However, very little is known about how it assembles into a tetramer and how long the tetramer stays intact. In this computational study, we provide a molecular dynamics based analysis of the structural stability and allosteric site dynamics in SAMHD1. We have investigated the allosteric links which assemble and hold the tetramer together. We have also extended this analysis to a regulatory mutant of SAMHD1. Experimental studies have indicated that phosphorylation of T592 downregulates HIV-1 restriction. A similar result is also achieved by a phosphomimetic mutation T592E. While a mechanistic understanding of the process is still elusive, the loss of structural integrity of the enzyme is conjectured to be the cause of the impaired dNTPase activity of the T592E mutant. MD simulations show that the T592E mutation causes slightly elevated local motions which remain confined to the short helix (residues 591-595), which contains the phosphorylation site and do not cause long-range destabilization of the SAMHD1 tetramer within the timeframe of the simulations. Thus, the regulatory mechanism of SAMHD1 is a more subtle mechanism than has been previously suspected. Proteins 2017; 85:1266-1275. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Kajwal Kumar Patra
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India, 400076
| | - Akash Bhattacharya
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229-3900
| | - Swati Bhattacharya
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India, 400076
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44
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Herold N, Rudd SG, Ljungblad L, Sanjiv K, Myrberg IH, Paulin CBJ, Heshmati Y, Hagenkort A, Kutzner J, Page BDG, Calderón-Montaño JM, Loseva O, Jemth AS, Bulli L, Axelsson H, Tesi B, Valerie NCK, Höglund A, Bladh J, Wiita E, Sundin M, Uhlin M, Rassidakis G, Heyman M, Tamm KP, Warpman-Berglund U, Walfridsson J, Lehmann S, Grandér D, Lundbäck T, Kogner P, Henter JI, Helleday T, Schaller T. Targeting SAMHD1 with the Vpx protein to improve cytarabine therapy for hematological malignancies. Nat Med 2017; 23:256-263. [PMID: 28067901 DOI: 10.1038/nm.4265] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/12/2016] [Indexed: 02/03/2023]
Abstract
The cytostatic deoxycytidine analog cytarabine (ara-C) is the most active agent available against acute myelogenous leukemia (AML). Together with anthracyclines, ara-C forms the backbone of AML treatment for children and adults. In AML, both the cytotoxicity of ara-C in vitro and the clinical response to ara-C therapy are correlated with the ability of AML blasts to accumulate the active metabolite ara-C triphosphate (ara-CTP), which causes DNA damage through perturbation of DNA synthesis. Differences in expression levels of known transporters or metabolic enzymes relevant to ara-C only partially account for patient-specific differential ara-CTP accumulation in AML blasts and response to ara-C treatment. Here we demonstrate that the deoxynucleoside triphosphate (dNTP) triphosphohydrolase SAM domain and HD domain 1 (SAMHD1) promotes the detoxification of intracellular ara-CTP pools. Recombinant SAMHD1 exhibited ara-CTPase activity in vitro, and cells in which SAMHD1 expression was transiently reduced by treatment with the simian immunodeficiency virus (SIV) protein Vpx were dramatically more sensitive to ara-C-induced cytotoxicity. CRISPR-Cas9-mediated disruption of the gene encoding SAMHD1 sensitized cells to ara-C, and this sensitivity could be abrogated by ectopic expression of wild-type (WT), but not dNTPase-deficient, SAMHD1. Mouse models of AML lacking SAMHD1 were hypersensitive to ara-C, and treatment ex vivo with Vpx sensitized primary patient-derived AML blasts to ara-C. Finally, we identified SAMHD1 as a risk factor in cohorts of both pediatric and adult patients with de novo AML who received ara-C treatment. Thus, SAMHD1 expression levels dictate patient sensitivity to ara-C, providing proof-of-concept that the targeting of SAMHD1 by Vpx could be an attractive therapeutic strategy for potentiating ara-C efficacy in hematological malignancies.
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Affiliation(s)
- Nikolas Herold
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Sean G Rudd
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Linda Ljungblad
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Kumar Sanjiv
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ida Hed Myrberg
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Cynthia B J Paulin
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Yaser Heshmati
- Department of Medicine, Center of Hematology and Regenerative Medicine, Karolinska Hospital and Karolinska Institutet, Stockholm, Sweden
| | - Anna Hagenkort
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Juliane Kutzner
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Brent D G Page
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - José M Calderón-Montaño
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Olga Loseva
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ann-Sofie Jemth
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lorenzo Bulli
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Hanna Axelsson
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Chemical Biology Consortium, Stockholm, Sweden
| | - Bianca Tesi
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Nicholas C K Valerie
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Andreas Höglund
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Julia Bladh
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Elisée Wiita
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Mikael Sundin
- Division of Pediatrics, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.,Paediatric Blood Disorders, Immunodeficiency and Stem Cell Transplantation, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden
| | - Michael Uhlin
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.,Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden
| | | | - Mats Heyman
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | | | - Ulrika Warpman-Berglund
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Julian Walfridsson
- Department of Medicine, Center of Hematology and Regenerative Medicine, Karolinska Hospital and Karolinska Institutet, Stockholm, Sweden
| | - Sören Lehmann
- Department of Medicine, Center of Hematology and Regenerative Medicine, Karolinska Hospital and Karolinska Institutet, Stockholm, Sweden.,Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Dan Grandér
- Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden
| | - Thomas Lundbäck
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Chemical Biology Consortium, Stockholm, Sweden
| | - Per Kogner
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Jan-Inge Henter
- Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, and Karolinska University Hospital, Stockholm, Sweden
| | - Thomas Helleday
- Science for Life Laboratory, Division of Translational Medicine and Chemical Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Torsten Schaller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
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45
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Schott K, Riess M, König R. Role of Innate Genes in HIV Replication. Curr Top Microbiol Immunol 2017; 419:69-111. [PMID: 28685292 DOI: 10.1007/82_2017_29] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cells use an elaborate innate immune surveillance and defense system against virus infections. Here, we discuss recent studies that reveal how HIV-1 is sensed by the innate immune system. Furthermore, we present mechanisms on the counteraction of HIV-1. We will provide an overview how HIV-1 actively utilizes host cellular factors to avoid sensing. Additionally, we will summarize effectors of the innate response that provide an antiviral cellular state. HIV-1 has evolved passive mechanism to avoid restriction and to regulate the innate response. We review in detail two prominent examples of these cellular factors: (i) NLRX1, a negative regulator of the innate response that HIV-1 actively usurps to block cytosolic innate sensing; (ii) SAMHD1, a restriction factor blocking the virus at the reverse transcription step that HIV-1 passively avoids to escape sensing.
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Affiliation(s)
- Kerstin Schott
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany
| | - Maximilian Riess
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225, Langen, Germany. .,Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA. .,German Center for Infection Research (DZIF), 63225, Langen, Germany.
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46
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Wang Z, Bhattacharya A, Villacorta J, Diaz-Griffero F, Ivanov DN. Allosteric Activation of SAMHD1 Protein by Deoxynucleotide Triphosphate (dNTP)-dependent Tetramerization Requires dNTP Concentrations That Are Similar to dNTP Concentrations Observed in Cycling T Cells. J Biol Chem 2016; 291:21407-21413. [PMID: 27566548 DOI: 10.1074/jbc.c116.751446] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 08/25/2016] [Indexed: 12/16/2022] Open
Abstract
SAMHD1 is a dNTP hydrolase, whose activity is required for maintaining low dNTP concentrations in non-cycling T cells, dendritic cells, and macrophages. SAMHD1-dependent dNTP depletion is thought to impair retroviral replication in these cells, but the relationship between the dNTPase activity and retroviral restriction is not fully understood. In this study, we investigate allosteric activation of SAMHD1 by deoxynucleotide-dependent tetramerization and measure how the lifetime of the enzymatically active tetramer is affected by different dNTP ligands bound in the allosteric site. The EC50dNTP values for SAMHD1 activation by dNTPs are in the 2-20 μm range, and the half-life of the assembled tetramer after deoxynucleotide depletion varies from minutes to hours depending on what dNTP is bound in the A2 allosteric site. Comparison of the wild-type SAMHD1 and the T592D mutant reveals that the phosphomimetic mutation affects the rates of tetramer dissociation, but has no effect on the equilibrium of allosteric activation by deoxynucleotides. Collectively, our data suggest that deoxynucleotide-dependent tetramerization contributes to regulation of deoxynucleotide levels in cycling cells, whereas in non-cycling cells restrictive to retroviral replication, SAMHD1 activation is likely to be achieved through a distinct mechanism.
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Affiliation(s)
- Zhonghua Wang
- From the Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229 and
| | - Akash Bhattacharya
- From the Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229 and
| | - Jessica Villacorta
- From the Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229 and
| | - Felipe Diaz-Griffero
- the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Dmitri N Ivanov
- From the Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78229 and
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