1
|
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.
Collapse
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.
| |
Collapse
|
2
|
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.
Collapse
|
3
|
Sharifi HJ, Paine DN, Fazzari VA, Tipple AF, Patterson E, de Noronha CMC. Sulforaphane Reduces SAMHD1 Phosphorylation To Protect Macrophages from HIV-1 Infection. J Virol 2022; 96:e0118722. [PMID: 36377871 PMCID: PMC9749475 DOI: 10.1128/jvi.01187-22] [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: 07/29/2022] [Accepted: 10/24/2022] [Indexed: 11/16/2022] Open
Abstract
The cellular protein SAMHD1 is important for DNA repair, suppressing LINE elements, controlling deoxynucleoside triphosphate (dNTP) concentrations, maintaining HIV-1 latency, and preventing excessive type I interferon responses. SAMHD1 is also a potent inhibitor of HIV-1 and other significant viral pathogens. Infection restriction is due in part to the deoxynucleoside triphosphatase (dNTPase) activity of SAMHD1 but is also mediated through a dNTPase-independent mechanism that has been described but not explored. The phosphorylation of SAMHD1 at threonine 592 (T592) controls many of its functions. Retroviral restriction, irrespective of dNTPase activity, is linked to unphosphorylated T592. Sulforaphane (SFN), an isothiocyanate, protects macrophages from HIV infection by mobilizing the transcription factor and antioxidant response regulator Nrf2. Here, we show that SFN and other clinically relevant Nrf2 mobilizers reduce SAMHD1 T592 phosphorylation to protect macrophages from HIV-1. We further show that SFN, through Nrf2, triggers the upregulation of the cell cycle control protein p21 in human monocyte-derived macrophages to contribute to SAMHD1 activation. We additionally present data that support another, potentially redox-dependent mechanism employed by SFN to contribute to SAMHD1 activation through reduced phosphorylation. This work establishes the use of exogenous Nrf2 mobilizers as a novel way to study virus restriction by SAMHD1 and highlights the Nrf2 pathway as a potential target for the therapeutic control of SAMHD1 cellular and antiviral functions. IMPORTANCE Here, we show, for the first time, that the treatment of macrophages with Nrf2 mobilizers, known activators of antioxidant responses, increases the fraction of SAMHD1 without a regulatory phosphate at position 592. We demonstrate that this decreases infection of macrophages by HIV-1. Phosphorylated SAMHD1 is important for DNA repair, the suppression of LINE elements, the maintenance of HIV-1 in a latent state, and the prevention of excessive type I interferon responses, while unphosphorylated SAMHD1 blocks HIV infection. SAMHD1 impacts many viruses and is involved in various cancers, so knowledge of how it works and how it is regulated has broad implications for the development of therapeutics. Redox-modulating therapeutics are already in clinical use or under investigation for the treatment of many conditions. Thus, understanding the impact of redox modifiers on controlling SAMHD1 phosphorylation is important for many areas of research in microbiology and beyond.
Collapse
Affiliation(s)
- H. John Sharifi
- Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | - Dakota N. Paine
- Albany College of Pharmacy and Health Sciences, Albany, New York, USA
| | | | | | - Emilee Patterson
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA
| | - Carlos M. C. de Noronha
- Department of Immunology and Microbial Disease, Albany Medical College, Albany, New York, USA
| |
Collapse
|
4
|
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: 4] [Impact Index Per Article: 2.0] [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.
Collapse
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:
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Zhang Z, Li P, Sun P. Expression of SAMHD1 and its mutation on prognosis of colon cancer. Oncol Lett 2022; 24:303. [PMID: 35949607 PMCID: PMC9353240 DOI: 10.3892/ol.2022.13423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/31/2022] [Indexed: 12/24/2022] Open
Abstract
The expression of sterile α motif and histidine/aspartic acid domain-containing protein 1 (SAMHD1) and its mutation play a key role in the prognosis of colon cancer. The aim of the present study was to investigate the mechanism and the role of SAMHD1 in colon cancer. Microarray data from 187 patients with colon cancer and 45 adjacent normal tissue obtained from the Gene Expression Omnibus (GEO) were analyzed. A protein-protein interaction (PPI) network was constructed to identify key genes associated with colon cancer prognosis. Cox proportional hazard regression and survival analyses were performed to identify the potential for SAMHD1 to serve as a prognostic biomarker. Immunohistochemistry (IHC) and immunofluorescence (IF) were performed to assess the expression levels and distribution of SAMHD1 in tissues and cells. Western blotting (WB) and Cell Counting Kit-8 (CCK-8) assays were used to identify the proliferation and apoptotic effects of SAMHD1 on HT-29 (Cas9-SAMHD1) cell lines. A total of 6,905 consistently differentially expressed genes were identified in the GEO database. Through the PPI network, SAMHD1 was found to be associated with Kirsten rat sarcoma virus (KRAS). SAMHD1 expression was negatively associated with KRAS. Proportional hazards regression and survival analyses demonstrated that low expression of SAMHD1 was associated with increased patient mortality. IHC and IF results demonstrated that SAMHD1 expression in patients with colon cancer was decreased compared with controls (both P<0.05). CCK-8 and WB results showed that proliferation was significantly promoted, and the expression levels of apoptosis-related proteins were significantly inhibited in the D137N and D311A groups as a result of a mutation in the deoxynucleoside triphosphohydrolase (dNTPase) site (both P<0.05 vs. wild-type). Proliferation was inhibited and apoptosis-related protein expression levels were promoted in the wild-type (WT) and D137N groups following 20 µg/ml 5-fluorouracil (5-FU) treatment (both P<0.05). WB and CCK-8 results showed cell proliferation was promoted and cell apoptosis-related protein expression was inhibited in the D137N group following treatment with 20 µg/ml 5-FU (all P<0.05) compared with the WT group. In conclusion, SAMHD1 expression was low in colon cancer. The dNTPase function of SAMHD1 may inhibit colon cancer cell proliferation and may enhance apoptosis. In addition, first-line chemotherapy with 5-FU has a time-dependent effect, which may provide novel options for clinical treatment of colon cancer.
Collapse
Affiliation(s)
- Zhou Zhang
- Translational Medical Centre, Wuxi No. 2 People's Hospital, Affiliated Wuxi Clinical College of Nantong University, Wuxi, Jiangsu 214002, P.R. China
| | - Ping Li
- Department of Pathology, Wuxi No. 2 People's Hospital, Affiliated Wuxi Clinical College of Nantong University, Wuxi, Jiangsu 214002, P.R. China
| | - Ping Sun
- Department of Pathology, Wuxi No. 2 People's Hospital, Affiliated Wuxi Clinical College of Nantong University, Wuxi, Jiangsu 214002, P.R. China
| |
Collapse
|
7
|
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] [Key Words] [MESH Headings] [Grants] [Track Full Text] [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.
Collapse
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.
| |
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
SAMHD1 Functions and Human Diseases. Viruses 2020; 12:v12040382. [PMID: 32244340 PMCID: PMC7232136 DOI: 10.3390/v12040382] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [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.
Collapse
|
11
|
Rudd SG, Tsesmetzis N, Sanjiv K, Paulin CBJ, Sandhow L, Kutzner J, Hed Myrberg I, Bunten SS, Axelsson H, Zhang SM, Rasti A, Mäkelä P, Coggins SA, Tao S, Suman S, Branca RM, Mermelekas G, Wiita E, Lee S, Walfridsson J, Schinazi RF, Kim B, Lehtiö J, Rassidakis GZ, Pokrovskaja Tamm K, Warpman‐Berglund U, Heyman M, Grandér D, Lehmann S, Lundbäck T, Qian H, Henter J, Schaller T, Helleday T, Herold N. Ribonucleotide reductase inhibitors suppress SAMHD1 ara-CTPase activity enhancing cytarabine efficacy. EMBO Mol Med 2020; 12:e10419. [PMID: 31950591 PMCID: PMC7059017 DOI: 10.15252/emmm.201910419] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 01/23/2023] Open
Abstract
The deoxycytidine analogue cytarabine (ara-C) remains the backbone treatment of acute myeloid leukaemia (AML) as well as other haematological and lymphoid malignancies, but must be combined with other chemotherapeutics to achieve cure. Yet, the underlying mechanism dictating synergistic efficacy of combination chemotherapy remains largely unknown. The dNTPase SAMHD1, which regulates dNTP homoeostasis antagonistically to ribonucleotide reductase (RNR), limits ara-C efficacy by hydrolysing the active triphosphate metabolite ara-CTP. Here, we report that clinically used inhibitors of RNR, such as gemcitabine and hydroxyurea, overcome the SAMHD1-mediated barrier to ara-C efficacy in primary blasts and mouse models of AML, displaying SAMHD1-dependent synergy with ara-C. We present evidence that this is mediated by dNTP pool imbalances leading to allosteric reduction of SAMHD1 ara-CTPase activity. Thus, SAMHD1 constitutes a novel biomarker for combination therapies of ara-C and RNR inhibitors with immediate consequences for clinical practice to improve treatment of AML.
Collapse
|
12
|
Zhang Z, Zheng L, Yu Y, Wu J, Yang F, Xu Y, Guo Q, Wu X, Cao S, Cao L, Song X. Involvement of SAMHD1 in dNTP homeostasis and the maintenance of genomic integrity and oncotherapy (Review). Int J Oncol 2020; 56:879-888. [PMID: 32319570 DOI: 10.3892/ijo.2020.4988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/07/2020] [Indexed: 11/06/2022] Open
Abstract
Sterile alpha motif and histidine/aspartic acid domain‑containing protein 1 (SAMHD1), the only deoxynucleotide triphosphate (dNTP) hydrolase in eukaryotes, plays a crucial role in regulating the dynamic balance and ratio of cellular dNTP pools. Furthermore, SAMHD1 has been reported to be involved in the pathological process of several diseases. Homozygous SAMHD1 mutations have been identified in immune system disorders, such as autoimmune disease Aicardi‑Goutières syndrome (AGS), whose primary pathogenesis is associated with the abnormal accumulation and disproportion of dNTPs. SAMHD1 is also considered to be an intrinsic virus‑restriction factor by suppressing the viral infection process, including reverse transcription, replication, packaging and transmission. In addition, SAMHD1 has been shown to promote genome integrity during homologous recombination following DNA damage, thus being considered a promising candidate for oncotherapy applications. The present review summarizes the molecular mechanisms of SAMHD1 regarding the regulation of dNTP homeostasis and DNA damage response. Additionally, its potential effects on tumorigenesis and oncotherapy are reported.
Collapse
Affiliation(s)
- Zhou Zhang
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Lixia Zheng
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Yang Yu
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Jinying Wu
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Fan Yang
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Yingxi Xu
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Qiqiang Guo
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Xuan Wu
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Sunrun Cao
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Liu Cao
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| | - Xiaoyu Song
- College of Basic Medical Science, Institute of Translational Medicine, China Medical University, Shenyang, Liaoning 110122, P.R. China
| |
Collapse
|
13
|
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.
Collapse
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.
| |
Collapse
|
14
|
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.
Collapse
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
| |
Collapse
|
15
|
Patra KK, Bhattacharya A, Bhattacharya S. Molecular dynamics investigation of a redox switch in the anti-HIV protein SAMHD1. Proteins 2019; 87:748-759. [PMID: 31017331 DOI: 10.1002/prot.25701] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/11/2019] [Accepted: 04/22/2019] [Indexed: 12/17/2022]
Abstract
HIV-1 is restricted in macrophages and certain quiescent myeloid cells due to a "Scorched Earth" dNTP starvation strategy attributed to the sterile alpha motif and HD domain protein-SAMHD1. Active SAMHD1 tetramers are assembled by GTP-Mg+2-dNTP cross bridges and cleave the triphosphate groups of dNTPs at a K m of ~10 μM, which is consistent with dNTP concentrations in cycling cells, but far higher than the equivalent concentration in quiescent cells. Given the substantial disparity between the dNTP concentrations required to activate SAMHD1 tetramers (~10 μM) and the dNTP concentrations in noncycling cells (~10 nM), the possibility of alternate enzymatically active forms of SAMHD1, including monomers remains open. In particular, the possibility of redox regulation of such monomers is also an open question. There have been experimental studies on the regulation of SAMHD1 by Glutathione driven redox reactions recently. Therefore, in this work, we have performed all-atom molecular dynamics simulations to study the dynamics of monomeric SAMHD1 constructs in the context of the three redox-susceptible Cysteine residues and compared them to monomers assembled within a tetramer. Our results indicate that assembly into a tetramer causes ordering of the catalytic core and increased solvent accessibility of the Catalytic Site. We have also found that glutathionylation of surface exposed C522 causes long range allosteric disruptions extending into the protein core. Finally, we see evidence suggesting a transient interaction between C522 and C341. Such a disulfide linkage has been hypothesized by experimental models, but has never been observed in crystal structures before.
Collapse
Affiliation(s)
- Kajwal Kumar Patra
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Akash Bhattacharya
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Swati Bhattacharya
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| |
Collapse
|
16
|
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 PMCID: PMC6487861 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] [MESH Headings] [Grants] [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.
Collapse
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.
| |
Collapse
|
17
|
Knecht KM, Buzovetsky O, Schneider C, Thomas D, Srikanth V, Kaderali L, Tofoleanu F, Reiss K, Ferreirós N, Geisslinger G, Batista VS, Ji X, Cinatl J, Keppler OT, Xiong Y. The structural basis for cancer drug interactions with the catalytic and allosteric sites of SAMHD1. Proc Natl Acad Sci U S A 2018; 115:E10022-E10031. [PMID: 30305425 PMCID: PMC6205433 DOI: 10.1073/pnas.1805593115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that depletes cellular dNTPs in noncycling cells to promote genome stability and to inhibit retroviral and herpes viral replication. In addition to being substrates, cellular nucleotides also allosterically regulate SAMHD1 activity. Recently, it was shown that high expression levels of SAMHD1 are also correlated with significantly worse patient responses to nucleotide analog drugs important for treating a variety of cancers, including acute myeloid leukemia (AML). In this study, we used biochemical, structural, and cellular methods to examine the interactions of various cancer drugs with SAMHD1. We found that both the catalytic and the allosteric sites of SAMHD1 are sensitive to sugar modifications of the nucleotide analogs, with the allosteric site being significantly more restrictive. We crystallized cladribine-TP, clofarabine-TP, fludarabine-TP, vidarabine-TP, cytarabine-TP, and gemcitabine-TP in the catalytic pocket of SAMHD1. We found that all of these drugs are substrates of SAMHD1 and that the efficacy of most of these drugs is affected by SAMHD1 activity. Of the nucleotide analogs tested, only cladribine-TP with a deoxyribose sugar efficiently induced the catalytically active SAMHD1 tetramer. Together, these results establish a detailed framework for understanding the substrate specificity and allosteric activation of SAMHD1 with regard to nucleotide analogs, which can be used to improve current cancer and antiviral therapies.
Collapse
Affiliation(s)
- Kirsten M Knecht
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Olga Buzovetsky
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Constanze Schneider
- Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany
| | - Dominique Thomas
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt, Goethe University of Frankfurt, 60590 Frankfurt, Germany
- Zentrum für Arzneimittelforschung, -entwicklung, und -sicherheit, Goethe University of Frankfurt, 60590 Frankfurt, Germany
| | - Vishok Srikanth
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Lars Kaderali
- Institute of Bioinformatics, University Medicine Greifswald, 17475 Greifswald, Germany
| | - Florentina Tofoleanu
- Department of Chemistry, Yale University, New Haven, CT 06520
- National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Krystle Reiss
- Department of Chemistry, Yale University, New Haven, CT 06520
| | - Nerea Ferreirós
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt, Goethe University of Frankfurt, 60590 Frankfurt, Germany
- Zentrum für Arzneimittelforschung, -entwicklung, und -sicherheit, Goethe University of Frankfurt, 60590 Frankfurt, Germany
| | - Gerd Geisslinger
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt, Goethe University of Frankfurt, 60590 Frankfurt, Germany
- Zentrum für Arzneimittelforschung, -entwicklung, und -sicherheit, Goethe University of Frankfurt, 60590 Frankfurt, Germany
- Project Group Translational Medicine and Pharmacology, Frauenhofer Institute for Molecular Biology and Applied Ecology, 60590 Frankfurt, Germany
| | | | - Xiaoyun Ji
- The State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210023 Jiangsu, China
| | - Jindrich Cinatl
- Institute of Medical Virology, University Hospital Frankfurt, 60596 Frankfurt, Germany
| | - Oliver T Keppler
- Max von Pettenkofer-Institute, Department of Virology, Ludwig Maximilians University, 80336 Munich, Germany
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520;
| |
Collapse
|
18
|
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.
Collapse
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
| |
Collapse
|
19
|
p21 Restricts HIV-1 in Monocyte-Derived Dendritic Cells through the Reduction of Deoxynucleoside Triphosphate Biosynthesis and Regulation of SAMHD1 Antiviral Activity. J Virol 2017; 91:JVI.01324-17. [PMID: 28931685 DOI: 10.1128/jvi.01324-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023] Open
Abstract
HIV-1 infection of noncycling cells, such as dendritic cells (DCs), is impaired due to limited availability of deoxynucleoside triphosphates (dNTPs), which are needed for HIV-1 reverse transcription. The levels of dNTPs are tightly regulated during the cell cycle and depend on the balance between dNTP biosynthesis and degradation. SAMHD1 potently blocks HIV-1 replication in DCs, although the underlying mechanism is still unclear. SAMHD1 has been reported to be able to degrade dNTPs and viral nucleic acids, which may both hamper HIV-1 reverse transcription. The relative contribution of these activities may differ in cycling and noncycling cells. Here, we show that inhibition of HIV-1 replication in monocyte-derived DCs (MDDCs) is associated with an increased expression of p21cip1/waf, a cell cycle regulator that is involved in the differentiation and maturation of DCs. Induction of p21 in MDDCs decreases the pool of dNTPs and increases the antiviral active isoform of SAMHD1. Although both processes are complementary in inhibiting HIV-1 replication, the antiviral activity of SAMHD1 in our primary cell model appears to be, at least partially, independent of its dNTPase activity. The reduction in the pool of dNTPs in MDDCs appears rather mostly due to a p21-mediated suppression of several enzymes involved in dNTP synthesis (i.e., RNR2, TYMS, and TK-1). These results are important to better understand the interplay between HIV-1 and DCs and may inform the design of new therapeutic approaches to decrease viral dissemination and improve immune responses against HIV-1.IMPORTANCE DCs play a key role in the induction of immune responses against HIV. However, HIV has evolved ways to exploit these cells, facilitating immune evasion and virus dissemination. We have found that the expression of p21, a cyclin-dependent kinase inhibitor involved in cell cycle regulation and monocyte differentiation and maturation, potentially can contribute to the inhibition of HIV-1 replication in monocyte-derived DCs through multiple mechanisms. p21 decreased the size of the intracellular dNTP pool. In parallel, p21 prevented SAMHD1 phosphorylation and promoted SAMHD1 dNTPase-independent antiviral activity. Thus, induction of p21 resulted in conditions that allowed the effective inhibition of HIV-1 replication through complementary mechanisms. Overall, p21 appears to be a key regulator of HIV infection in myeloid cells.
Collapse
|
20
|
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.
Collapse
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
| |
Collapse
|
21
|
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.
Collapse
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
| |
Collapse
|