1
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Ivanov KI, Yang H, Sun R, Li C, Guo D. The emerging role of SARS-CoV-2 nonstructural protein 1 (nsp1) in epigenetic regulation of host gene expression. FEMS Microbiol Rev 2024; 48:fuae023. [PMID: 39231808 PMCID: PMC11418652 DOI: 10.1093/femsre/fuae023] [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: 06/19/2024] [Revised: 08/30/2024] [Accepted: 09/03/2024] [Indexed: 09/06/2024] Open
Abstract
Infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes widespread changes in epigenetic modifications and chromatin architecture in the host cell. Recent evidence suggests that SARS-CoV-2 nonstructural protein 1 (nsp1) plays an important role in driving these changes. Previously thought to be primarily involved in host translation shutoff and cellular mRNA degradation, nsp1 has now been shown to be a truly multifunctional protein that affects host gene expression at multiple levels. The functions of nsp1 are surprisingly diverse and include not only the downregulation of cellular mRNA translation and stability, but also the inhibition of mRNA export from the nucleus, the suppression of host immune signaling, and, most recently, the epigenetic regulation of host gene expression. In this review, we first summarize the current knowledge on SARS-CoV-2-induced changes in epigenetic modifications and chromatin structure. We then focus on the role of nsp1 in epigenetic reprogramming, with a particular emphasis on the silencing of immune-related genes. Finally, we discuss potential molecular mechanisms underlying the epigenetic functions of nsp1 based on evidence from SARS-CoV-2 interactome studies.
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Affiliation(s)
- Konstantin I Ivanov
- Guangzhou National Laboratory, Guangzhou, 510320, China
- Department of Microbiology, University of Helsinki, Helsinki, 00014, Finland
| | - Haibin Yang
- MOE Key Laboratory of Tropical Disease Control, Center for Infection and Immunity Studies (CIIS), School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-Sen University, Shenzhen, 518107, China
| | - Ruixue Sun
- Guangzhou National Laboratory, Guangzhou, 510320, China
| | - Chunmei Li
- MOE Key Laboratory of Tropical Disease Control, Center for Infection and Immunity Studies (CIIS), School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-Sen University, Shenzhen, 518107, China
| | - Deyin Guo
- Guangzhou National Laboratory, Guangzhou, 510320, China
- MOE Key Laboratory of Tropical Disease Control, Center for Infection and Immunity Studies (CIIS), School of Medicine, Shenzhen Campus of Sun Yat-Sen University, Sun Yat-Sen University, Shenzhen, 518107, China
- State Key Laboratory of Respiratory Diseases, National Clinical Research Center for Respiratory Diseases, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510182, China
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2
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Abe KM, Li G, He Q, Grant T, Lim CJ. Small LEA proteins mitigate air-water interface damage to fragile cryo-EM samples during plunge freezing. Nat Commun 2024; 15:7705. [PMID: 39231985 PMCID: PMC11375022 DOI: 10.1038/s41467-024-52091-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Accepted: 08/27/2024] [Indexed: 09/06/2024] Open
Abstract
Air-water interface (AWI) interactions during cryo-electron microscopy (cryo-EM) sample preparation cause significant sample loss, hindering structural biology research. Organisms like nematodes and tardigrades produce Late Embryogenesis Abundant (LEA) proteins to withstand desiccation stress. Here we show that these LEA proteins, when used as additives during plunge freezing, effectively mitigate AWI damage to fragile multi-subunit molecular samples. The resulting high-resolution cryo-EM maps are comparable to or better than those obtained using existing AWI damage mitigation methods. Cryogenic electron tomography reveals that particles are localized at specific interfaces, suggesting LEA proteins form a barrier at the AWI. This interaction may explain the observed sample-dependent preferred orientation of particles. LEA proteins offer a simple, cost-effective, and adaptable approach for cryo-EM structural biologists to overcome AWI-related sample damage, potentially revitalizing challenging projects and advancing the field of structural biology.
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Affiliation(s)
- Kaitlyn M Abe
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Gan Li
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, WI, 53715, USA
| | - Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Timothy Grant
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- John and Jeanne Rowe Center for Research in Virology, Morgridge Institute for Research, Madison, WI, 53715, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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3
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Manthei KA, Munson LM, Nandakumar J, Simmons LA. Structural and biochemical characterization of the mitomycin C repair exonuclease MrfB. Nucleic Acids Res 2024; 52:6347-6359. [PMID: 38661211 PMCID: PMC11194089 DOI: 10.1093/nar/gkae308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/03/2024] [Accepted: 04/10/2024] [Indexed: 04/26/2024] Open
Abstract
Mitomycin C (MMC) repair factor A (mrfA) and factor B (mrfB), encode a conserved helicase and exonuclease that repair DNA damage in the soil-dwelling bacterium Bacillus subtilis. Here we have focused on the characterization of MrfB, a DEDDh exonuclease in the DnaQ superfamily. We solved the structure of the exonuclease core of MrfB to a resolution of 2.1 Å, in what appears to be an inactive state. In this conformation, a predicted α-helix containing the catalytic DEDDh residue Asp172 adopts a random coil, which moves Asp172 away from the active site and results in the occupancy of only one of the two catalytic Mg2+ ions. We propose that MrfB resides in this inactive state until it interacts with DNA to become activated. By comparing our structure to an AlphaFold prediction as well as other DnaQ-family structures, we located residues hypothesized to be important for exonuclease function. Using exonuclease assays we show that MrfB is a Mg2+-dependent 3'-5' DNA exonuclease. We show that Leu113 aids in coordinating the 3' end of the DNA substrate, and that a basic loop is important for substrate binding. This work provides insight into the function of a recently discovered bacterial exonuclease important for the repair of MMC-induced DNA adducts.
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Affiliation(s)
- Kelly A Manthei
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lia M Munson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Lyle A Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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4
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Mei M, Cupic A, Miorin L, Ye C, Cagatay T, Zhang K, Patel K, Wilson N, McDonald WH, Crossland NA, Lo M, Rutkowska M, Aslam S, Mena I, Martinez-Sobrido L, Ren Y, García-Sastre A, Fontoura BMA. Inhibition of mRNA nuclear export promotes SARS-CoV-2 pathogenesis. Proc Natl Acad Sci U S A 2024; 121:e2314166121. [PMID: 38768348 PMCID: PMC11145185 DOI: 10.1073/pnas.2314166121] [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: 08/16/2023] [Accepted: 04/09/2024] [Indexed: 05/22/2024] Open
Abstract
The nonstructural protein 1 (Nsp1) of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) is a virulence factor that targets multiple cellular pathways to inhibit host gene expression and antiviral response. However, the underlying mechanisms of the various Nsp1-mediated functions and their contributions to SARS-CoV-2 virulence remain unclear. Among the targets of Nsp1 is the mRNA (messenger ribonucleic acid) export receptor NXF1-NXT1, which mediates nuclear export of mRNAs from the nucleus to the cytoplasm. Based on Nsp1 crystal structure, we generated mutants on Nsp1 surfaces and identified an acidic N-terminal patch that is critical for interaction with NXF1-NXT1. Photoactivatable Nsp1 probe reveals the RNA Recognition Motif (RRM) domain of NXF1 as an Nsp1 N-terminal binding site. By mutating the Nsp1 N-terminal acidic patch, we identified a separation-of-function mutant of Nsp1 that retains its translation inhibitory function but substantially loses its interaction with NXF1 and reverts Nsp1-mediated mRNA export inhibition. We then generated a recombinant (r)SARS-CoV-2 mutant on the Nsp1 N-terminal acidic patch and found that this surface is key to promote NXF1 binding and inhibition of host mRNA nuclear export, viral replication, and pathogenicity in vivo. Thus, these findings provide a mechanistic understanding of Nsp1-mediated mRNA export inhibition and establish the importance of this pathway in the virulence of SARS-CoV-2.
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Affiliation(s)
- Menghan Mei
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Anastasija Cupic
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Lisa Miorin
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Chengjin Ye
- Texas Biomedical Research Institute, San Antonio, TX78227
| | - Tolga Cagatay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai200031, China
| | - Komal Patel
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
- Arpirnaut Program, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Natalie Wilson
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - W. Hayes McDonald
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Nicholas A. Crossland
- Comparative Pathology Laboratory, National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA02215
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA02118
| | - Ming Lo
- Comparative Pathology Laboratory, National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA02215
| | - Magdalena Rutkowska
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Sadaf Aslam
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Ignacio Mena
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | | | - Yi Ren
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY10029
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Beatriz M. A. Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
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5
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Mullins EA, Salay LE, Durie CL, Bradley NP, Jackman JE, Ohi MD, Chazin WJ, Eichman BF. A mechanistic model of primer synthesis from catalytic structures of DNA polymerase α-primase. Nat Struct Mol Biol 2024; 31:777-790. [PMID: 38491139 PMCID: PMC11102853 DOI: 10.1038/s41594-024-01227-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 01/12/2024] [Indexed: 03/18/2024]
Abstract
The mechanism by which polymerase α-primase (polα-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of Xenopus laevis polα-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5' end facilitates handoff of the primer to polα and increases polα processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polα and primase affinities for the varied conformations along the chimeric primer-template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polα-primase.
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Affiliation(s)
- Elwood A Mullins
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Lauren E Salay
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | - Clarissa L Durie
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Biochemistry, University of Missouri, Columbia, MO, USA
| | - Noah P Bradley
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Jane E Jackman
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
- Center for RNA Biology, The Ohio State University, Columbus, OH, USA
| | - Melanie D Ohi
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Walter J Chazin
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
| | - Brandt F Eichman
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA.
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
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6
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Yin Z, Kilkenny ML, Ker DS, Pellegrini L. CryoEM insights into RNA primer synthesis by the human primosome. FEBS J 2024; 291:1813-1829. [PMID: 38335062 DOI: 10.1111/febs.17082] [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: 09/21/2023] [Revised: 11/24/2023] [Accepted: 01/26/2024] [Indexed: 02/12/2024]
Abstract
Eukaryotic DNA replication depends on the primosome - a complex of DNA polymerase alpha (Pol α) and primase - to initiate DNA synthesis by polymerisation of an RNA-DNA primer. Primer synthesis requires the tight coordination of primase and polymerase activities. Recent cryo-electron microscopy (cryoEM) analyses have elucidated the extensive conformational transitions required for RNA primer handover between primase and Pol α and primer elongation by Pol α. Because of the intrinsic flexibility of the primosome, however, structural information about the initiation of RNA primer synthesis is still lacking. Here, we capture cryoEM snapshots of the priming reaction to reveal the conformational trajectory of the human primosome that brings DNA primase subunits 1 and 2 (PRIM1 and PRIM2, respectively) together, poised for RNA synthesis. Furthermore, we provide experimental evidence for the continuous association of primase subunit PRIM2 with the RNA primer during primer synthesis, and for how both initiation and termination of RNA primer polymerisation are licenced by specific rearrangements of DNA polymerase alpha catalytic subunit (POLA1), the polymerase subunit of Pol α. Our findings fill a critical gap in our understanding of the conformational changes that underpin the synthesis of the RNA primer by the primosome. Together with existing evidence, they provide a complete description of the structural dynamics of the human primosome during DNA replication initiation.
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Affiliation(s)
- Zhan Yin
- Department of Biochemistry, University of Cambridge, UK
| | | | - De-Sheng Ker
- Department of Biochemistry, University of Cambridge, UK
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7
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Baranovskiy AG, Morstadt LM, Babayeva ND, Tahirov TH. Human primosome requires replication protein A when copying DNA with inverted repeats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.584335. [PMID: 38559116 PMCID: PMC10979909 DOI: 10.1101/2024.03.11.584335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The human primosome, a four-subunit complex of primase and DNA polymerase alpha (Polα), initiates DNA synthesis on both chromosome strands by generating chimeric RNA-DNA primers for loading DNA polymerases delta and epsilon (Polε). Replication protein A (RPA) tightly binds to single-stranded DNA strands, protecting them from nucleolytic digestion and unauthorized transactions. We report here that RPA plays a critical role for the human primosome during DNA synthesis across inverted repeats prone to hairpin formation. On other alternatively structured DNA forming a G-quadruplex, RPA provides no assistance for primosome. A stimulatory effect of RPA on DNA synthesis across hairpins was also observed for the catalytic domain of Polα but not of Polε. The important factors for an efficient hairpin bypass by primosome are the high affinity of RPA to DNA based on four DNA-binding domains and the interaction of the winged-helix-turn-helix domain of RPA with Polα. Binding studies indicate that this interaction stabilizes the RPA/Polα complex on the primed template. This work provides insight into a cooperative action of RPA and primosome on DNA, which is critical for DNA synthesis across inverted repeats.
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8
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Manthei KA, Munson LM, Nandakumar J, Simmons LA. Structural and biochemical characterization of the mitomycin C repair exonuclease MrfB. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580553. [PMID: 38405983 PMCID: PMC10889028 DOI: 10.1101/2024.02.15.580553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mitomycin C (MMC) repair factor A (mrfA) and factor B (mrfB), encode a conserved helicase and exonuclease that repair DNA damage in the soil-dwelling bacterium Bacillus subtilis. Here we have focused on the characterization of MrfB, a DEDDh exonuclease in the DnaQ superfamily. We solved the structure of the exonuclease core of MrfB to a resolution of 2.1 Å, in what appears to be an inactive state. In this conformation, a predicted α-helix containing the catalytic DEDDh residue Asp172 adopts a random coil, which moves Asp172 away from the active site and results in the occupancy of only one of the two catalytic Mg2+ ions. We propose that MrfB resides in this inactive state until it interacts with DNA to become activated. By comparing our structure to an AlphaFold prediction as well as other DnaQ-family structures, we located residues hypothesized to be important for exonuclease function. Using exonuclease assays we show that MrfB is a Mg2+-dependent 3'-5' DNA exonuclease. We show that Leu113 aids in coordinating the 3' end of the DNA substrate, and that a basic loop is important for substrate binding. This work provides insight into the function of a recently discovered bacterial exonuclease important for the repair of MMC-induced DNA adducts.
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Affiliation(s)
- Kelly A. Manthei
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lia M. Munson
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Lyle A. Simmons
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
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9
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Abe KM, Lim CJ. Small LEA proteins as an effective air-water interface protectant for fragile samples during cryo-EM grid plunge freezing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.06.579238. [PMID: 38370693 PMCID: PMC10871254 DOI: 10.1101/2024.02.06.579238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Sample loss due to air-water interface (AWI) interactions is a significant challenge during cryo-electron microscopy (cryo-EM) sample grid plunge freezing. We report that small Late Embryogenesis Abundant (LEA) proteins, which naturally bind to AWI, can protect samples from AWI damage during plunge freezing. This protection is demonstrated with two LEA proteins from nematodes and tardigrades, which rescued the cryo-EM structural determination outcome of two fragile multisubunit protein complexes.
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Affiliation(s)
- Kaitlyn M. Abe
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706
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10
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Karousis ED, Schubert K, Ban N. Coronavirus takeover of host cell translation and intracellular antiviral response: a molecular perspective. EMBO J 2024; 43:151-167. [PMID: 38200146 PMCID: PMC10897431 DOI: 10.1038/s44318-023-00019-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 11/01/2023] [Accepted: 11/24/2023] [Indexed: 01/12/2024] Open
Abstract
Coronaviruses are a group of related RNA viruses that cause respiratory diseases in humans and animals. Understanding the mechanisms of translation regulation during coronaviral infections is critical for developing antiviral therapies and preventing viral spread. Translation of the viral single-stranded RNA genome in the host cell cytoplasm is an essential step in the life cycle of coronaviruses, which affects the cellular mRNA translation landscape in many ways. Here we discuss various viral strategies of translation control, including how members of the Betacoronavirus genus shut down host cell translation and suppress host innate immune functions, as well as the role of the viral non-structural protein 1 (Nsp1) in the process. We also outline the fate of viral RNA, considering stress response mechanisms triggered in infected cells, and describe how unique viral RNA features contribute to programmed ribosomal -1 frameshifting, RNA editing, and translation shutdown evasion.
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Affiliation(s)
- Evangelos D Karousis
- Multidisciplinary Center for Infectious Diseases, University of Bern, Bern, Switzerland
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Katharina Schubert
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Nenad Ban
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
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11
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He Q, Lim CJ. Models for human telomere C-strand fill-in by CST-Polα-primase. Trends Biochem Sci 2023; 48:860-872. [PMID: 37586999 PMCID: PMC10528720 DOI: 10.1016/j.tibs.2023.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Telomere maintenance is essential for the genome integrity of eukaryotes, and this function is underpinned by the two-step telomeric DNA synthesis process: telomere G-overhang extension by telomerase and complementary strand fill-in by DNA polymerase alpha-primase (polα-primase). Compared to the telomerase step, the telomere C-strand fill-in mechanism is less understood. Recent studies have provided new insights into how telomeric single-stranded DNA-binding protein CTC1-STN1-TEN1 (CST) and polα-primase coordinate to synthesize the telomeric C-strand for telomere overhang fill-in. Cryogenic electron microscopy (cryo-EM) structures of CST-polα-primase complexes have provided additional insights into how they assemble at telomeric templates and de novo synthesize the telomere C-strand. In this review, we discuss how these latest findings coalesce with existing understanding to develop a human telomere C-strand fill-in mechanism model.
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Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
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12
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Zabrady K, Li AWH, Doherty AJ. Mechanism of primer synthesis by Primase-Polymerases. Curr Opin Struct Biol 2023; 82:102652. [PMID: 37459807 DOI: 10.1016/j.sbi.2023.102652] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/15/2023] [Accepted: 06/19/2023] [Indexed: 09/16/2023]
Abstract
Members of the primase-polymerase (Prim-Pol) superfamily are found in all domains of life and play diverse roles in genome stability, including primer synthesis during DNA replication, lesion repair and damage tolerance. This review focuses primarily on Prim-Pol members capable of de novo primer synthesis that have experimentally derived structural models available. We discuss the mechanism of DNA primer synthesis initiation by Prim-Pol catalytic domains, based on recent structural and functional studies. We also describe a general model for primer initiation that also includes the ancillary domains/subunits, which stimulate the initiation of primer synthesis.
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Affiliation(s)
- Katerina Zabrady
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK. https://twitter.com/@KZabrady
| | - Arthur W H Li
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK.
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13
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Mullins EA, Salay LE, Durie CL, Bradley NP, Jackman JE, Ohi MD, Chazin WJ, Eichman BF. A mechanistic model of primer synthesis from catalytic structures of DNA polymerase α-primase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.533013. [PMID: 36993335 PMCID: PMC10055150 DOI: 10.1101/2023.03.16.533013] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The mechanism by which polymerase α-primase (polα-primase) synthesizes chimeric RNA-DNA primers of defined length and composition, necessary for replication fidelity and genome stability, is unknown. Here, we report cryo-EM structures of polα-primase in complex with primed templates representing various stages of DNA synthesis. Our data show how interaction of the primase regulatory subunit with the primer 5'-end facilitates handoff of the primer to polα and increases polα processivity, thereby regulating both RNA and DNA composition. The structures detail how flexibility within the heterotetramer enables synthesis across two active sites and provide evidence that termination of DNA synthesis is facilitated by reduction of polα and primase affinities for the varied conformations along the chimeric primer/template duplex. Together, these findings elucidate a critical catalytic step in replication initiation and provide a comprehensive model for primer synthesis by polα-primase.
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14
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Abstract
It has been known for decades that telomerase extends the 3' end of linear eukaryotic chromosomes and dictates the telomeric repeat sequence based on the template in its RNA. However, telomerase does not mitigate sequence loss at the 5' ends of chromosomes, which results from lagging strand DNA synthesis and nucleolytic processing. Therefore, a second enzyme is needed to keep telomeres intact: DNA polymerase α/Primase bound to Ctc1-Stn1-Ten1 (CST). CST-Polα/Primase maintains telomeres through a fill-in reaction that replenishes the lost sequences at the 5' ends. CST not only serves to maintain telomeres but also determines their length by keeping telomerase from overelongating telomeres. Here we discuss recent data on the evolution, structure, function, and recruitment of mammalian CST-Polα/Primase, highlighting the role of this complex and telomere length control in human disease.
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Affiliation(s)
- Sarah W Cai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
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15
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He Q, Baranovskiy AG, Morstadt LM, Lisova AE, Babayeva ND, Lusk BL, Lim CJ, Tahirov TH. Structures of human primosome elongation complexes. Nat Struct Mol Biol 2023; 30:579-583. [PMID: 37069376 PMCID: PMC10268227 DOI: 10.1038/s41594-023-00971-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 03/20/2023] [Indexed: 04/19/2023]
Abstract
The synthesis of RNA-DNA primer by primosome requires coordination between primase and DNA polymerase α subunits, which is accompanied by unknown architectural rearrangements of multiple domains. Using cryogenic electron microscopy, we solved a 3.6 Å human primosome structure caught at an early stage of RNA primer elongation with deoxynucleotides. The structure confirms a long-standing role of primase large subunit and reveals new insights into how primosome is limited to synthesizing short RNA-DNA primers.
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Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrey G Baranovskiy
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Lucia M Morstadt
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Alisa E Lisova
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Nigar D Babayeva
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA
| | - Benjamin L Lusk
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Tahir H Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE, USA.
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16
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Li G, Tang Z, Fan W, Wang X, Huang L, Jia Y, Wang M, Hu Z, Zhou Y. Atlas of interactions between SARS-CoV-2 macromolecules and host proteins. CELL INSIGHT 2023; 2:100068. [PMID: 37192911 PMCID: PMC9670597 DOI: 10.1016/j.cellin.2022.100068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/30/2022] [Accepted: 11/04/2022] [Indexed: 11/18/2022]
Abstract
The proteins and RNAs of viruses extensively interact with host proteins after infection. We collected and reanalyzed all available datasets of protein-protein and RNA-protein interactions related to SARS-CoV-2. We investigated the reproducibility of those interactions and made strict filters to identify highly confident interactions. We systematically analyzed the interaction network and identified preferred subcellular localizations of viral proteins, some of which such as ORF8 in ER and ORF7A/B in ER membrane were validated using dual fluorescence imaging. Moreover, we showed that viral proteins frequently interact with host machinery related to protein processing in ER and vesicle-associated processes. Integrating the protein- and RNA-interactomes, we found that SARS-CoV-2 RNA and its N protein closely interacted with stress granules including 40 core factors, of which we specifically validated G3BP1, IGF2BP1, and MOV10 using RIP and Co-IP assays. Combining CRISPR screening results, we further identified 86 antiviral and 62 proviral factors and associated drugs. Using network diffusion, we found additional 44 interacting proteins including two proviral factors previously validated. Furthermore, we showed that this atlas could be applied to identify the complications associated with COVID-19. All data are available in the AIMaP database (https://mvip.whu.edu.cn/aimap/) for users to easily explore the interaction map.
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Affiliation(s)
- Guangnan Li
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
| | - Zhidong Tang
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
| | - Weiliang Fan
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
| | - Xi Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Li Huang
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
| | - Yu Jia
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
| | - Manli Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Zhihong Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, China
| | - Yu Zhou
- College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Wuhan University, Wuhan, China
- State Key Laboratory of Virology, Wuhan University, Wuhan, China
- Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, China
- Institute for Advanced Studies, Wuhan University, Wuhan, China
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17
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Ma S, Damfo S, Lou J, Pinotsis N, Bowler MW, Haider S, Kozielski F. Two Ligand-Binding Sites on SARS-CoV-2 Non-Structural Protein 1 Revealed by Fragment-Based X-ray Screening. Int J Mol Sci 2022; 23:12448. [PMID: 36293303 PMCID: PMC9604401 DOI: 10.3390/ijms232012448] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
The regular reappearance of coronavirus (CoV) outbreaks over the past 20 years has caused significant health consequences and financial burdens worldwide. The most recent and still ongoing novel CoV pandemic, caused by Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) has brought a range of devastating consequences. Due to the exceptionally fast development of vaccines, the mortality rate of the virus has been curbed to a significant extent. However, the limitations of vaccination efficiency and applicability, coupled with the still high infection rate, emphasise the urgent need for discovering safe and effective antivirals against SARS-CoV-2 by suppressing its replication or attenuating its virulence. Non-structural protein 1 (nsp1), a unique viral and conserved leader protein, is a crucial virulence factor for causing host mRNA degradation, suppressing interferon (IFN) expression and host antiviral signalling pathways. In view of the essential role of nsp1 in the CoV life cycle, it is regarded as an exploitable target for antiviral drug discovery. Here, we report a variety of fragment hits against the N-terminal domain of SARS-CoV-2 nsp1 identified by fragment-based screening via X-ray crystallography. We also determined the structure of nsp1 at atomic resolution (0.99 Å). Binding affinities of hits against nsp1 and potential stabilisation were determined by orthogonal biophysical assays such as microscale thermophoresis and thermal shift assays. We identified two ligand-binding sites on nsp1, one deep and one shallow pocket, which are not conserved between the three medically relevant SARS, SARS-CoV-2 and MERS coronaviruses. Our study provides an excellent starting point for the development of more potent nsp1-targeting inhibitors and functional studies on SARS-CoV-2 nsp1.
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Affiliation(s)
- Shumeng Ma
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Shymaa Damfo
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Jiaqi Lou
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
| | - Nikos Pinotsis
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | | | - Shozeb Haider
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
- UCL Centre for Advanced Research Computing, University College London, London WC1H 9RN, UK
| | - Frank Kozielski
- School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK
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18
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Structure of Tetrahymena telomerase-bound CST with polymerase α-primase. Nature 2022; 608:813-818. [PMID: 35831498 PMCID: PMC9728385 DOI: 10.1038/s41586-022-04931-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 06/06/2022] [Indexed: 02/03/2023]
Abstract
Telomeres are the physical ends of linear chromosomes. They are composed of short repeating sequences (such as TTGGGG in the G-strand for Tetrahymena thermophila) of double-stranded DNA with a single-strand 3' overhang of the G-strand and, in humans, the six shelterin proteins: TPP1, POT1, TRF1, TRF2, RAP1 and TIN21,2. TPP1 and POT1 associate with the 3' overhang, with POT1 binding the G-strand3 and TPP1 (in complex with TIN24) recruiting telomerase via interaction with telomerase reverse transcriptase5 (TERT). The telomere DNA ends are replicated and maintained by telomerase6, for the G-strand, and subsequently DNA polymerase α-primase7,8 (PolαPrim), for the C-strand9. PolαPrim activity is stimulated by the heterotrimeric complex CTC1-STN1-TEN110-12 (CST), but the structural basis of the recruitment of PolαPrim and CST to telomere ends remains unknown. Here we report cryo-electron microscopy (cryo-EM) structures of Tetrahymena CST in the context of the telomerase holoenzyme, in both the absence and the presence of PolαPrim, and of PolαPrim alone. Tetrahymena Ctc1 binds telomerase subunit p50, a TPP1 orthologue, on a flexible Ctc1 binding motif revealed by cryo-EM and NMR spectroscopy. The PolαPrim polymerase subunit POLA1 binds Ctc1 and Stn1, and its interface with Ctc1 forms an entry port for G-strand DNA to the POLA1 active site. We thus provide a snapshot of four key components that are required for telomeric DNA synthesis in a single active complex-telomerase-core ribonucleoprotein, p50, CST and PolαPrim-that provides insights into the recruitment of CST and PolαPrim and the handoff between G-strand and C-strand synthesis.
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19
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Gao K, Wang R, Chen J, Cheng L, Frishcosy J, Huzumi Y, Qiu Y, Schluckbier T, Wei X, Wei GW. Methodology-Centered Review of Molecular Modeling, Simulation, and Prediction of SARS-CoV-2. Chem Rev 2022; 122:11287-11368. [PMID: 35594413 PMCID: PMC9159519 DOI: 10.1021/acs.chemrev.1c00965] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Despite tremendous efforts in the past two years, our understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), virus-host interactions, immune response, virulence, transmission, and evolution is still very limited. This limitation calls for further in-depth investigation. Computational studies have become an indispensable component in combating coronavirus disease 2019 (COVID-19) due to their low cost, their efficiency, and the fact that they are free from safety and ethical constraints. Additionally, the mechanism that governs the global evolution and transmission of SARS-CoV-2 cannot be revealed from individual experiments and was discovered by integrating genotyping of massive viral sequences, biophysical modeling of protein-protein interactions, deep mutational data, deep learning, and advanced mathematics. There exists a tsunami of literature on the molecular modeling, simulations, and predictions of SARS-CoV-2 and related developments of drugs, vaccines, antibodies, and diagnostics. To provide readers with a quick update about this literature, we present a comprehensive and systematic methodology-centered review. Aspects such as molecular biophysics, bioinformatics, cheminformatics, machine learning, and mathematics are discussed. This review will be beneficial to researchers who are looking for ways to contribute to SARS-CoV-2 studies and those who are interested in the status of the field.
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Affiliation(s)
- Kaifu Gao
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Rui Wang
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Jiahui Chen
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Limei Cheng
- Clinical
Pharmacology and Pharmacometrics, Bristol
Myers Squibb, Princeton, New Jersey 08536, United States
| | - Jaclyn Frishcosy
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Yuta Huzumi
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Yuchi Qiu
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Tom Schluckbier
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Xiaoqi Wei
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
| | - Guo-Wei Wei
- Department
of Mathematics, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Electrical and Computer Engineering, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
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20
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Lou Z, Rao Z. The Life of SARS-CoV-2 Inside Cells: Replication-Transcription Complex Assembly and Function. Annu Rev Biochem 2022; 91:381-401. [PMID: 35729072 DOI: 10.1146/annurev-biochem-052521-115653] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The persistence of the coronavirus disease 2019 (COVID-19) pandemic has resulted in increasingly disruptive impacts, and it has become the most devastating challenge to global health in a century. The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants challenges the currently available therapeutics for clinical application. Nonstructural proteins (also known as replicase proteins) with versatile biological functions play central roles in viral replication and transcription inside the host cells, and they are the most conserved target proteins among the SARS-CoV-2 variants. Specifically, they constitute the replication-transcription complexes (RTCs) dominating the synthesis of viral RNA. Knowledge of themolecular mechanisms of nonstructural proteins and their assembly into RTCs will benefit the development of antivirals targeting them against existing or potentially emerging variants. In this review, we summarize current knowledge of the structures and functions of coronavirus nonstructural proteins as well as the assembly and functions of RTCs in the life cycle of the virus.
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Affiliation(s)
- Zhiyong Lou
- Ministry of Education Key Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing, China; ,
| | - Zihe Rao
- Ministry of Education Key Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing, China; , .,Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,School of Life Sciences, Tsinghua University, Beijing, China.,State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences and College of Pharmacy, Nankai University, Tianjin, China.,National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,Guangzhou Laboratory, Guangzhou, China
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21
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Liu Q, Chi S, Dmytruk K, Dmytruk O, Tan S. Coronaviral Infection and Interferon Response: The Virus-Host Arms Race and COVID-19. Viruses 2022; 14:v14071349. [PMID: 35891331 PMCID: PMC9325157 DOI: 10.3390/v14071349] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 02/07/2023] Open
Abstract
The recent pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in unprecedented morbidity and mortality worldwide. The host cells use a number of pattern recognition receptors (PRRs) for early detection of coronavirus infection, and timely interferon secretion is highly effective against SARS-CoV-2 infection. However, the virus has developed many strategies to delay interferon secretion and disarm cellular defense by intervening in interferon-associated signaling pathways on multiple levels. As a result, some COVID-19 patients suffered dramatic susceptibility to SARS-CoV-2 infection, while another part of the population showed only mild or no symptoms. One hypothesis suggests that functional differences in innate immune integrity could be the key to such variability. This review tries to decipher possible interactions between SARS-CoV-2 proteins and human antiviral interferon sensors. We found that SARS-CoV-2 actively interacts with PRR sensors and antiviral pathways by avoiding interferon suppression, which could result in severe COVID-19 pathogenesis. Finally, we summarize data on available antiviral pharmaceutical options that have shown potential to reduce COVID-19 morbidity and mortality in recent clinical trials.
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Affiliation(s)
- Qi Liu
- Department of Immunology, School of Basic Medicine, Chongqing Medical University, Chongqing 400010, China;
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence: (Q.L.); (S.T.)
| | - Sensen Chi
- Department of Immunology, School of Basic Medicine, Chongqing Medical University, Chongqing 400010, China;
| | - Kostyantyn Dmytruk
- Department of Molecular Genetics and Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, 79005 Lviv, Ukraine; (K.D.); (O.D.)
| | - Olena Dmytruk
- Department of Molecular Genetics and Biotechnology, Institute of Cell Biology, National Academy of Sciences of Ukraine, 79005 Lviv, Ukraine; (K.D.); (O.D.)
- Institute of Biology and Biotechnology, University of Rzeszow, 35-601 Rzeszow, Poland
| | - Shuai Tan
- Department of Immunology, School of Basic Medicine, Chongqing Medical University, Chongqing 400010, China;
- Correspondence: (Q.L.); (S.T.)
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22
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Baranovskiy AG, Lisova AE, Morstadt LM, Babayeva ND, Tahirov TH. Insight into RNA-DNA primer length counting by human primosome. Nucleic Acids Res 2022; 50:6264-6270. [PMID: 35689638 PMCID: PMC9226528 DOI: 10.1093/nar/gkac492] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/19/2022] [Accepted: 06/08/2022] [Indexed: 11/15/2022] Open
Abstract
The human primosome, a four-subunit complex of primase and DNA polymerase alpha (Polα), synthesizes chimeric RNA–DNA primers of a limited length for DNA polymerases delta and epsilon to initiate DNA replication on both chromosome strands. Despite recent structural insights into the action of its two catalytic centers, the mechanism of DNA synthesis termination is still unclear. Here we report results of functional and structural studies revealing how the human primosome counts RNA–DNA primer length and timely terminates DNA elongation. Using a single-turnover primer extension assay, we defined two factors that determine a mature primer length (∼35-mer): (i) a tight interaction of the C-terminal domain of the DNA primase large subunit (p58C) with the primer 5′-end, and (ii) flexible tethering of p58C and the DNA polymerase alpha catalytic core domain (p180core) to the primosome platform domain by extended linkers. The obtained data allow us to conclude that p58C is a key regulator of all steps of RNA–DNA primer synthesis. The above-described findings provide a notable insight into the mechanism of DNA synthesis termination by a eukaryotic primosome, an important process for ensuring successful primer handover to replication DNA polymerases and for maintaining genome integrity.
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Affiliation(s)
- Andrey G Baranovskiy
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA
| | - Alisa E Lisova
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA
| | - Lucia M Morstadt
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA
| | - Nigar D Babayeva
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA
| | - Tahir H Tahirov
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center. University of Nebraska Medical Center, Omaha, NE, USA
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23
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Cai SW, Zinder JC, Svetlov V, Bush MW, Nudler E, Walz T, de Lange T. Cryo-EM structure of the human CST-Polα/primase complex in a recruitment state. Nat Struct Mol Biol 2022; 29:813-819. [PMID: 35578024 PMCID: PMC9371972 DOI: 10.1038/s41594-022-00766-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/30/2022] [Indexed: 12/03/2022]
Abstract
The CST–Polα/primase complex is essential for telomere maintenance and functions to counteract resection at double-strand breaks. We report a 4.6-Å resolution cryo-EM structure of human CST–Polα/primase, captured prior to catalysis in a recruitment state stabilized by chemical cross-linking. Our structure reveals an evolutionarily conserved interaction between the C-terminal domain of the catalytic POLA1 subunit and an N-terminal expansion in metazoan CTC1. Cross-linking mass spectrometry and negative-stain EM analysis provide insight into CST binding by the flexible POLA1 N-terminus. Finally, Coats plus syndrome disease mutations previously characterized to disrupt formation of the CST–Polα/primase complex map to protein–protein interfaces observed in the recruitment state. Together, our results shed light on the architecture and stoichiometry of the metazoan fill-in machinery. Cryo-EM analysis of the human CST–Polα/primase complex reveals a metazoan-specific mode of interaction between CST and DNA polymerase α that is proposed to function in telomeric recruitment of Polα/primase for C-strand maintenance.
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Affiliation(s)
- Sarah W Cai
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA.,Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - John C Zinder
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
| | - Vladimir Svetlov
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Martin W Bush
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA.
| | - Titia de Lange
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA.
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24
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Kilkenny ML, Veale CE, Guppy A, Hardwick SW, Chirgadze DY, Rzechorzek NJ, Maman JD, Pellegrini L. Structural basis for the interaction of SARS-CoV-2 virulence factor nsp1 with DNA polymerase α-primase. Protein Sci 2022; 31:333-344. [PMID: 34719824 PMCID: PMC8661717 DOI: 10.1002/pro.4220] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/28/2021] [Accepted: 10/28/2021] [Indexed: 11/21/2022]
Abstract
The molecular mechanisms that drive the infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-the causative agent of coronavirus disease 2019 (COVID-19)-are under intense current scrutiny to understand how the virus operates and to uncover ways in which the disease can be prevented or alleviated. Recent proteomic screens of the interactions between viral and host proteins have identified the human proteins targeted by SARS-CoV-2. The DNA polymerase α (Pol α)-primase complex or primosome-responsible for initiating DNA synthesis during genomic duplication-was identified as a target of nonstructural protein 1 (nsp1), a major virulence factor in the SARS-CoV-2 infection. Here, we validate the published reports of the interaction of nsp1 with the primosome by demonstrating direct binding with purified recombinant components and providing a biochemical characterization of their interaction. Furthermore, we provide a structural basis for the interaction by elucidating the cryo-electron microscopy structure of nsp1 bound to the primosome. Our findings provide biochemical evidence for the reported targeting of Pol α by the virulence factor nsp1 and suggest that SARS-CoV-2 interferes with Pol α's putative role in the immune response during the viral infection.
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Affiliation(s)
| | | | - Amir Guppy
- Department of BiochemistryUniversity of CambridgeCambridgeCB2 1GAUK
| | | | | | - Neil J. Rzechorzek
- Department of BiochemistryUniversity of CambridgeCambridgeCB2 1GAUK
- Present address:
The Francis Crick InstituteLondonNW1 1ATUK
| | - Joseph D. Maman
- Department of BiochemistryUniversity of CambridgeCambridgeCB2 1GAUK
| | - Luca Pellegrini
- Department of BiochemistryUniversity of CambridgeCambridgeCB2 1GAUK
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