1
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Chechik M, Greive SJ, Antson AA, Jenkins HT. Structural basis for DNA recognition by a viral genome-packaging machine. Proc Natl Acad Sci U S A 2024; 121:e2406138121. [PMID: 39116131 PMCID: PMC11331095 DOI: 10.1073/pnas.2406138121] [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: 03/25/2024] [Accepted: 07/09/2024] [Indexed: 08/10/2024] Open
Abstract
DNA recognition is critical for assembly of double-stranded DNA viruses, particularly for the initiation of packaging the viral genome into the capsid. The key component that recognizes viral DNA is the small terminase protein. Despite prior studies, the molecular mechanism for DNA recognition remained elusive. Here, we address this question by identifying the minimal site in the bacteriophage HK97 genome specifically recognized by the small terminase and determining the structure of this complex by cryoEM. The circular small terminase employs an entirely unexpected mechanism in which DNA transits through the central tunnel, and sequence-specific recognition takes place as it emerges. This recognition stems from a substructure formed by the N- and C-terminal segments of two adjacent protomers which are unstructured when DNA is absent. Such interaction ensures continuous engagement of the small terminase with DNA, enabling it to slide along the DNA while simultaneously monitoring its sequence. This mechanism allows locating and instigating packaging initiation and termination precisely at the specific cos sequence.
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Affiliation(s)
- Maria Chechik
- York Structural Biology Laboratory, Department of Chemistry, University of York, YorkYO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, YorkYO10 5NG, United Kingdom
| | - Sandra J. Greive
- York Structural Biology Laboratory, Department of Chemistry, University of York, YorkYO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, YorkYO10 5NG, United Kingdom
| | - Alfred A. Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, YorkYO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, YorkYO10 5NG, United Kingdom
| | - Huw T. Jenkins
- York Structural Biology Laboratory, Department of Chemistry, University of York, YorkYO10 5DD, United Kingdom
- York Biomedical Research Institute, University of York, YorkYO10 5NG, United Kingdom
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2
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Chechik M, Greive SJ, Antson AA, Jenkins HT. Structure of HK97 small terminase:DNA complex unveils a novel DNA binding mechanism by a circular protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.17.549218. [PMID: 37503206 PMCID: PMC10370121 DOI: 10.1101/2023.07.17.549218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
DNA recognition is critical for assembly of double-stranded DNA viruses, in particular for the initiation of packaging the viral genome into the capsid. DNA packaging has been extensively studied for three archetypal bacteriophage systems: cos, pac and phi29. We identified the minimal site within the cos region of bacteriophage HK97 specifically recognised by the small terminase and determined a cryoEM structure for the small terminase:DNA complex. This nonameric circular protein utilizes a previously unknown mechanism of DNA binding. While DNA threads through the central tunnel, unexpectedly, DNA-recognition is generated at its exit by a substructure formed by the N- and C-terminal segments of two adjacent protomers of the terminase which are unstructured in the absence of DNA. Such interaction ensures continuous engagement of the small terminase with DNA, allowing sliding along DNA while simultaneously checking the DNA sequence. This mechanism allows locating and instigating packaging initiation and termination precisely at the cos site.
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Affiliation(s)
- Maria Chechik
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | | | - Alfred A. Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - Huw T. Jenkins
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
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3
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Lokareddy RK, Hou CFD, Li F, Yang R, Cingolani G. Viral Small Terminase: A Divergent Structural Framework for a Conserved Biological Function. Viruses 2022; 14:v14102215. [PMID: 36298770 PMCID: PMC9611059 DOI: 10.3390/v14102215] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/07/2022] Open
Abstract
The genome packaging motor of bacteriophages and herpesviruses is built by two terminase subunits, known as large (TerL) and small (TerS), both essential for viral genome packaging. TerL structure, composition, and assembly to an empty capsid, as well as the mechanisms of ATP-dependent DNA packaging, have been studied in depth, shedding light on the chemo-mechanical coupling between ATP hydrolysis and DNA translocation. Instead, significantly less is known about the small terminase subunit, TerS, which is dispensable or even inhibitory in vitro, but essential in vivo. By taking advantage of the recent revolution in cryo-electron microscopy (cryo-EM) and building upon a wealth of crystallographic structures of phage TerSs, in this review, we take an inventory of known TerSs studied to date. Our analysis suggests that TerS evolved and diversified into a flexible molecular framework that can conserve biological function with minimal sequence and quaternary structure conservation to fit different packaging strategies and environmental conditions.
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4
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Niazi M, Florio TJ, Yang R, Lokareddy RK, Swanson NA, Gillilan RE, Cingolani G. Biophysical analysis of Pseudomonas-phage PaP3 small terminase suggests a mechanism for sequence-specific DNA-binding by lateral interdigitation. Nucleic Acids Res 2020; 48:11721-11736. [PMID: 33125059 PMCID: PMC7672466 DOI: 10.1093/nar/gkaa866] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 09/19/2020] [Accepted: 10/21/2020] [Indexed: 12/17/2022] Open
Abstract
The genome packaging motor of tailed bacteriophages and herpesviruses is a powerful nanomachine built by several copies of a large (TerL) and a small (TerS) terminase subunit. The motor assembles transiently at the portal vertex of an empty precursor capsid (or procapsid) to power genome encapsidation. Terminase subunits have been studied in-depth, especially in classical bacteriophages that infect Escherichia coli or Salmonella, yet, less is known about the packaging motor of Pseudomonas-phages that have increasing biomedical relevance. Here, we investigated the small terminase subunit from three Podoviridae phages that infect Pseudomonas aeruginosa. We found TerS is polymorphic in solution but assembles into a nonamer in its high-affinity heparin-binding conformation. The atomic structure of Pseudomonas phage PaP3 TerS, the first complete structure for a TerS from a cos phage, reveals nine helix-turn-helix (HTH) motifs asymmetrically arranged around a β-stranded channel, too narrow to accommodate DNA. PaP3 TerS binds DNA in a sequence-specific manner in vitro. X-ray scattering and molecular modeling suggest TerS adopts an open conformation in solution, characterized by dynamic HTHs that move around an oligomerization core, generating discrete binding crevices for DNA. We propose a model for sequence-specific recognition of packaging initiation sites by lateral interdigitation of DNA.
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Affiliation(s)
- Marzia Niazi
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Tyler J Florio
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Ruoyu Yang
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Ravi K Lokareddy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Nicholas A Swanson
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Richard E Gillilan
- Macromolecular Diffraction Facility, Cornell High Energy Synchrotron Source (MacCHESS), Cornell University, 161 Synchrotron Drive, Ithaca, NY 14853, USA
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
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5
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Identification of the First Gene Transfer Agent (GTA) Small Terminase in Rhodobacter capsulatus and Its Role in GTA Production and Packaging of DNA. J Virol 2019; 93:JVI.01328-19. [PMID: 31534034 PMCID: PMC6854486 DOI: 10.1128/jvi.01328-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 09/10/2019] [Indexed: 12/17/2022] Open
Abstract
Genetic exchange mediated by viruses of bacteria (bacteriophages) is the primary driver of rapid bacterial evolution. The priority of viruses is usually to propagate themselves. Most bacteriophages use the small terminase protein to identify their own genome and direct its inclusion into phage capsids. Gene transfer agents (GTAs) are descended from bacteriophages, but they instead package fragments of the entire bacterial genome without preference for their own genes. GTAs do not selectively target specific DNA, and no GTA small terminases are known. Here, we identified the small terminase from the model Rhodobacter capsulatus GTA, which then allowed prediction of analogues in other species. We examined the role of the small terminase in GTA production and propose a structural basis for random DNA packaging.IMPORTANCE Random transfer of any and all genes between bacteria could be influential in the spread of virulence or antimicrobial resistance genes. Discovery of the true prevalence of GTAs in sequenced genomes is hampered by their apparent similarity to bacteriophages. Our data allowed the prediction of small terminases in diverse GTA producer species, and defining the characteristics of a "GTA-type" terminase could be an important step toward novel GTA identification. Importantly, the GTA small terminase shares many features with its phage counterpart. We propose that the GTA terminase complex could become a streamlined model system to answer fundamental questions about double-stranded DNA (dsDNA) packaging by viruses that have not been forthcoming to date.
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6
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Dixit AB, Ray K, Black LW. A viral small terminase subunit (TerS) twin ring pac synapsis DNA packaging model is supported by fluorescent fusion proteins. Virology 2019; 536:39-48. [PMID: 31400548 PMCID: PMC6760839 DOI: 10.1016/j.virol.2019.07.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 07/22/2019] [Accepted: 07/24/2019] [Indexed: 11/23/2022]
Abstract
A bacteriophage T4 DNA "synapsis model" proposes that the bacteriophage T4 terminase small subunit (TerS) apposes two pac site containing dsDNA homologs to gauge concatemer maturation adequate for packaging initiation. N-terminus, C-terminus, or both ends modified fusion Ter S proteins retain function. Replacements of the TerS gene in the T4 genome with fusion genes encoding larger (18-45 kDa) TerS-eGFP and TerS-mCherry fluorescent fusion proteins function without significant change in phenotype. Co-infection and co-expression by T4 phages encoding TerS-eGFP and TerS-mCherry shows in vivo FRET in infected bacteria comparable to that of the purified, denatured and then renatured, mixed fusion proteins in vitro. FRET of purified, denatured-renatured, mixed temperature sensitive and native TerS fusion proteins at low and high temperature in vitro shows that TerS ring-like oligomer formation is essential for function in vivo. Super-resolution STORM and PALM microscopy of intercalating dye YOYO-1 DNA and photoactivatable TerS-PAmCherry-C1 fusions support accumulation of TerS dimeric or multiple ring-like oligomer structures containing DNA and gp16-mCherry in vivo as well as in vitro to regulate pac site cutting.
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Affiliation(s)
- Aparna Banerjee Dixit
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Krishanu Ray
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA; Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Lindsay W Black
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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7
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Weiditch SA, Seraphim TV, Houry WA, Kanelis V. Strategies for purification of the bacteriophage HK97 small and large terminase subunits that yield pure and homogeneous samples that are functional. Protein Expr Purif 2019; 160:45-55. [DOI: 10.1016/j.pep.2019.03.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/30/2019] [Accepted: 03/30/2019] [Indexed: 02/06/2023]
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8
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Genome Analysis of Two Novel Lytic Vibrio maritimus Phages Isolated from the Coastal Surface Seawater of Qingdao, China. Curr Microbiol 2019; 76:1225-1233. [DOI: 10.1007/s00284-019-01736-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 07/03/2019] [Indexed: 12/13/2022]
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9
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Liu Q, Han Y, Wang D, Wang Q, Liu X, Li Y, Song X, Wang M, Jiang Y, Meng Z, Shao H, McMinn A. Complete genomic sequence of bacteriophage J2-1: A novel Pseudoalteromonas phenolica phage isolated from the coastal water of Qingdao, China. Mar Genomics 2018. [DOI: 10.1016/j.margen.2017.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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10
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Meng X, Wang M, You S, Wang D, Li Y, Liu Z, Gao Y, Liu L, Zhang Y, Yan Z, Liu C, Jiang Y, Shao H. Characterization and Complete Genome Sequence of a Novel Siphoviridae Bacteriophage BS5. Curr Microbiol 2017; 74:815-820. [DOI: 10.1007/s00284-017-1221-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 02/17/2017] [Indexed: 10/19/2022]
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11
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Gao S, Zhang L, Rao VB. Exclusion of small terminase mediated DNA threading models for genome packaging in bacteriophage T4. Nucleic Acids Res 2016; 44:4425-39. [PMID: 26984529 PMCID: PMC4872099 DOI: 10.1093/nar/gkw184] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/04/2016] [Indexed: 11/17/2022] Open
Abstract
Tailed bacteriophages and herpes viruses use powerful molecular machines to package their genomes. The packaging machine consists of three components: portal, motor (large terminase; TerL) and regulator (small terminase; TerS). Portal, a dodecamer, and motor, a pentamer, form two concentric rings at the special five-fold vertex of the icosahedral capsid. Powered by ATPase, the motor ratchets DNA into the capsid through the portal channel. TerS is essential for packaging, particularly for genome recognition, but its mechanism is unknown and controversial. Structures of gear-shaped TerS rings inspired models that invoke DNA threading through the central channel. Here, we report that mutations of basic residues that line phage T4 TerS (gp16) channel do not disrupt DNA binding. Even deletion of the entire channel helix retained DNA binding and produced progeny phage in vivo. On the other hand, large oligomers of TerS (11-mers/12-mers), but not small oligomers (trimers to hexamers), bind DNA. These results suggest that TerS oligomerization creates a large outer surface, which, but not the interior of the channel, is critical for function, probably to wrap viral genome around the ring during packaging initiation. Hence, models involving TerS-mediated DNA threading may be excluded as an essential mechanism for viral genome packaging.
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Affiliation(s)
- Song Gao
- Department of Biology, The Catholic University of America, 620 Michigan Avenue Northeast, Washington, DC 20064, USA Jiangsu Key Laboratory of Marine Pharmaceutical Compound Screening, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Liang Zhang
- Department of Biology, The Catholic University of America, 620 Michigan Avenue Northeast, Washington, DC 20064, USA
| | - Venigalla B Rao
- Department of Biology, The Catholic University of America, 620 Michigan Avenue Northeast, Washington, DC 20064, USA
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12
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Complete Genomic Sequence of Bacteriophage H188: A Novel Vibrio kanaloae Phage Isolated from Yellow Sea. Curr Microbiol 2016; 72:628-33. [DOI: 10.1007/s00284-015-0984-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022]
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13
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Greive SJ, Fung HKH, Chechik M, Jenkins HT, Weitzel SE, Aguiar PM, Brentnall AS, Glousieau M, Gladyshev GV, Potts JR, Antson AA. DNA recognition for virus assembly through multiple sequence-independent interactions with a helix-turn-helix motif. Nucleic Acids Res 2015; 44:776-89. [PMID: 26673721 PMCID: PMC4737164 DOI: 10.1093/nar/gkv1467] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/30/2015] [Indexed: 11/14/2022] Open
Abstract
The helix-turn-helix (HTH) motif features frequently in protein DNA-binding assemblies. Viral pac site-targeting small terminase proteins possess an unusual architecture in which the HTH motifs are displayed in a ring, distinct from the classical HTH dimer. Here we investigate how such a circular array of HTH motifs enables specific recognition of the viral genome for initiation of DNA packaging during virus assembly. We found, by surface plasmon resonance and analytical ultracentrifugation, that individual HTH motifs of the Bacillus phage SF6 small terminase bind the packaging regions of SF6 and related SPP1 genome weakly, with little local sequence specificity. Nuclear magnetic resonance chemical shift perturbation studies with an arbitrary single-site substrate suggest that the HTH motif contacts DNA similarly to how certain HTH proteins contact DNA non-specifically. Our observations support a model where specificity is generated through conformational selection of an intrinsically bent DNA segment by a ring of HTHs which bind weakly but cooperatively. Such a system would enable viral gene regulation and control of the viral life cycle, with a minimal genome, conferring a major evolutionary advantage for SPP1-like viruses.
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Affiliation(s)
- Sandra J Greive
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Herman K H Fung
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK Department of Biology, University of York, York YO10 5DD, UK
| | - Maria Chechik
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Huw T Jenkins
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Stephen E Weitzel
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | - Pedro M Aguiar
- Department of Chemistry, University of York, York YO10 5DD, UK
| | | | - Matthieu Glousieau
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Grigory V Gladyshev
- Department of Biochemistry, School of Biology, Moscow State University, Moscow 119234, Russian Federation
| | | | - Alfred A Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
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14
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Hong C, Oksanen HM, Liu X, Jakana J, Bamford DH, Chiu W. A structural model of the genome packaging process in a membrane-containing double stranded DNA virus. PLoS Biol 2014; 12:e1002024. [PMID: 25514469 PMCID: PMC4267777 DOI: 10.1371/journal.pbio.1002024] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 11/03/2014] [Indexed: 02/01/2023] Open
Abstract
Two crucial steps in the virus life cycle are genome encapsidation to form an infective virion and genome exit to infect the next host cell. In most icosahedral double-stranded (ds) DNA viruses, the viral genome enters and exits the capsid through a unique vertex. Internal membrane-containing viruses possess additional complexity as the genome must be translocated through the viral membrane bilayer. Here, we report the structure of the genome packaging complex with a membrane conduit essential for viral genome encapsidation in the tailless icosahedral membrane-containing bacteriophage PRD1. We utilize single particle electron cryo-microscopy (cryo-EM) and symmetry-free image reconstruction to determine structures of PRD1 virion, procapsid, and packaging deficient mutant particles. At the unique vertex of PRD1, the packaging complex replaces the regular 5-fold structure and crosses the lipid bilayer. These structures reveal that the packaging ATPase P9 and the packaging efficiency factor P6 form a dodecameric portal complex external to the membrane moiety, surrounded by ten major capsid protein P3 trimers. The viral transmembrane density at the special vertex is assigned to be a hexamer of heterodimer of proteins P20 and P22. The hexamer functions as a membrane conduit for the DNA and as a nucleating site for the unique vertex assembly. Our structures show a conformational alteration in the lipid membrane after the P9 and P6 are recruited to the virion. The P8-genome complex is then packaged into the procapsid through the unique vertex while the genome terminal protein P8 functions as a valve that closes the channel once the genome is inside. Comparing mature virion, procapsid, and mutant particle structures led us to propose an assembly pathway for the genome packaging apparatus in the PRD1 virion.
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Affiliation(s)
- Chuan Hong
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hanna M. Oksanen
- Department of Biosciences and Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Xiangan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Joanita Jakana
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Dennis H. Bamford
- Department of Biosciences and Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Wah Chiu
- Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
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15
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Complete genomic sequence of the Vibrio alginolyticus lytic bacteriophage PVA1. Arch Virol 2014; 159:3447-51. [PMID: 25161033 DOI: 10.1007/s00705-014-2207-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 08/18/2014] [Indexed: 10/24/2022]
Abstract
A novel Vibrio alginolyticus lytic bacteriophage was isolated from sewage samples obtained from a local aquatic market. Morphological analysis revealed that the phage, designated as PVA1, belonged to the family Podoviridae. The complete genomic sequence of phage PVA1 contained 41,529 bp with a G + C content of 43.7 % and 75 putative open reading frames. The genome was grouped into four modules, including phage structure, DNA packaging, DNA replication and regulation, and some additional functions. Further genomic comparison of the phage PVA1 with other known phages showed no significant similarities. Genes related to virulence and lysogeny were not detected in the phage genome. Our results suggest that phage PVA1 may be classified as a new Vibrio phage. We believe that these phage genomic sequence data will provide useful basic information for further molecular research on this Vibrio phage and its host as well for determining its infection/interaction mechanisms.
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16
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Complete genome sequence of a polyvalent bacteriophage, phiKP26, active on Salmonella and Escherichia coli. Arch Virol 2013; 158:2395-8. [PMID: 23677676 DOI: 10.1007/s00705-013-1725-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 04/10/2013] [Indexed: 10/26/2022]
Abstract
Bacteriophages are viruses that specifically infect and lyse prokaryotic cells and therefore might be used as biocontrol agents. However, it is necessary to acquire genomic information to predict and understand the phage's characteristics for the efficient and safe use of bacteriophages as biocontrol agents against bacterial pathogens. In this study, the complete genome sequence of a novel enterobacteriophage, phiKP26, was determined by pyrosequencing. Genomic analysis of phiKP26 revealed a genome size of 47,285 bp with an overall G + C content of 44.3 %. Seventy-eight open reading frames (ORFs) in the phiKP26 genome were grouped into the modules of replication, DNA packaging, morphogenesis, cell lysis and absence of genes related to virulence and lysogeny.
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17
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Oliveira L, Tavares P, Alonso JC. Headful DNA packaging: Bacteriophage SPP1 as a model system. Virus Res 2013; 173:247-59. [DOI: 10.1016/j.virusres.2013.01.021] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 01/28/2013] [Accepted: 01/30/2013] [Indexed: 01/15/2023]
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18
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Daudén MI, Martín-Benito J, Sánchez-Ferrero JC, Pulido-Cid M, Valpuesta JM, Carrascosa JL. Large terminase conformational change induced by connector binding in bacteriophage T7. J Biol Chem 2013; 288:16998-17007. [PMID: 23632014 DOI: 10.1074/jbc.m112.448951] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During bacteriophage morphogenesis DNA is translocated into a preformed prohead by the complex formed by the portal protein, or connector, plus the terminase, which are located at an especial prohead vertex. The terminase is a powerful motor that converts ATP hydrolysis into mechanical movement of the DNA. Here, we have determined the structure of the T7 large terminase by electron microscopy. The five terminase subunits assemble in a toroid that encloses a channel wide enough to accommodate dsDNA. The structure of the complete connector-terminase complex is also reported, revealing the coupling between the terminase and the connector forming a continuous channel. The structure of the terminase assembled into the complex showed a different conformation when compared with the isolated terminase pentamer. To understand in molecular terms the terminase morphological change, we generated the terminase atomic model based on the crystallographic structure of its phage T4 counterpart. The docking of the threaded model in both terminase conformations showed that the transition between the two states can be achieved by rigid body subunit rotation in the pentameric assembly. The existence of two terminase conformations and its possible relation to the sequential DNA translocation may shed light into the molecular bases of the packaging mechanism of bacteriophage T7.
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Affiliation(s)
- María I Daudén
- Department of Macromolecular Structure, 28049 Madrid, Spain
| | | | - Juan C Sánchez-Ferrero
- Computational Systems Biology Group, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain
| | - Mar Pulido-Cid
- Department of Macromolecular Structure, 28049 Madrid, Spain
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19
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Leavitt JC, Gilcrease EB, Wilson K, Casjens SR. Function and horizontal transfer of the small terminase subunit of the tailed bacteriophage Sf6 DNA packaging nanomotor. Virology 2013; 440:117-33. [PMID: 23562538 DOI: 10.1016/j.virol.2013.02.023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 02/22/2013] [Accepted: 02/26/2013] [Indexed: 11/27/2022]
Abstract
Bacteriophage Sf6 DNA packaging series initiate at many locations across a 2kbp region. Our in vivo studies show that Sf6 small terminase subunit (TerS) protein recognizes a specific packaging (pac) site near the center of this region, that this site lies within the portion of the Sf6 gene that encodes the DNA-binding domain of TerS protein, that this domain of the TerS protein is responsible for the imprecision in Sf6 packaging initiation, and that the DNA-binding domain of TerS must be covalently attached to the domain that interacts with the rest of the packaging motor. The TerS DNA-binding domain is self-contained in that it apparently does not interact closely with the rest of the motor and it binds to a recognition site that lies within the DNA that encodes the domain. This arrangement has allowed the horizontal exchange of terS genes among phages to be very successful.
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Affiliation(s)
- Justin C Leavitt
- Biology Department, University of Utah, Salt Lake City, UT 84112, USA
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20
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Ren B, Pham TM, Surjadi R, Robinson CP, Le TK, Chandry PS, Peat TS, McKinstry WJ. Expression, purification, crystallization and preliminary X-ray diffraction analysis of a lactococcal bacteriophage small terminase subunit. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:275-9. [PMID: 23519803 PMCID: PMC3606573 DOI: 10.1107/s174430911300184x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Accepted: 01/18/2013] [Indexed: 11/10/2022]
Abstract
Terminases are enzymes that are required for the insertion of a single viral genome into the interior of a viral procapsid by a process referred to as 'encapsulation or packaging'. Many double-stranded DNA viruses such as bacteriophages T3, T4, T7, λ and SPP1, as well as herpes viruses, utilize terminase enzymes for this purpose. All the terminase enzymes described to date require two subunits, a small subunit referred to as TerS and a large subunit referred to as TerL, for in vivo activity. The TerS and TerL subunits interact with each other to form a functional hetero-oligomeric enzyme complex; however the stoichiometry and oligomeric state have not been determined. We have cloned, expressed and purified recombinant small terminase TerS from a 936 lactococcal bacteriophage strain ASCC454, initially isolated from a dairy factory. The terminase was crystallized using a combination of nanolitre sitting drops and vapour diffusion using sodium malonate as the precipitant, and crystallization optimized using standard vapour-diffusion hanging drops set up in the presence of a nitrogen atmosphere. The crystals belong to the P2 space group, with unit-cell parameters a=73.93, b=158.48, c=74.23 Å, and diffract to 2.42 Å resolution using synchrotron radiation. A self-rotation function calculation revealed that the terminase oligomerizes into an octamer in the asymmetric unit, although size-exclusion chromatography suggests that it is possible for it to form an oligomer of up to 13 subunits.
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Affiliation(s)
- Bin Ren
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - Tam M. Pham
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - Regina Surjadi
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - Christine P. Robinson
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - Thien-Kim Le
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - P. Scott Chandry
- Animal, Food and Health Sciences, CSIRO, Werribee, Victoria 3030, Australia
| | - Thomas S. Peat
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
| | - William J. McKinstry
- Materials Science and Engineering, CSIRO, 343 Royal Parade, Parkville, Victoria 3052, Australia
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21
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Nemecek D, Stepanek J, Thomas GJ. Raman Spectroscopy of Proteins and Nucleoproteins. ACTA ACUST UNITED AC 2013; Chapter 17:Unit17.8. [DOI: 10.1002/0471140864.ps1708s71] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Daniel Nemecek
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health Bethesda Maryland
- Central European Institute of Technology, Masaryk University Brno Czech Republic
| | - Josef Stepanek
- Charles University in Prague, Faculty of Mathematics and Physics, Institute of Physics Prague Czech Republic
| | - George J. Thomas
- School of Biological Sciences, University of Missouri‐Kansas City Kansas City Missouri
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22
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Abstract
Viruses protect their genetic information by enclosing the viral nucleic acid inside a protein shell (capsid), in a process known as genome packaging. Viruses follow essentially two main strategies to package their genome: Either they co-assemble their genetic material together with the capsid protein, or they assemble first an empty shell (procapsid) and then pump the genome inside the capsid with a molecular motor that uses the energy released by ATP hydrolysis. During packaging the viral nucleic acid is condensed to very high concentration by its careful arrangement in concentric layers inside the capsid. In this chapter we will first give an overview of the different strategies used for genome packaging to discuss later some specific virus models where the structures of the main proteins involved, and the biophysics underlying the packaging mechanism, have been well documented.
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Affiliation(s)
- Ana Cuervo
- Department of Macromolecular Structure, Centro Nacional de Biotecnología (CSIC), c/Darwin 3, Campus de Cantoblanco, 28049, Madrid, Spain
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23
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Zhao H, Kamau YN, Christensen TE, Tang L. Structural and functional studies of the phage Sf6 terminase small subunit reveal a DNA-spooling device facilitated by structural plasticity. J Mol Biol 2012; 423:413-26. [PMID: 22858866 DOI: 10.1016/j.jmb.2012.07.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 07/12/2012] [Accepted: 07/23/2012] [Indexed: 12/01/2022]
Abstract
In many DNA viruses, genome packaging is initiated by the small subunit of the packaging terminase, which specifically binds to the packaging signal on viral DNA and directs assembly of the terminase holoenzyme. We have experimentally mapped the DNA-interacting region on Shigella virus Sf6 terminase small subunit gp1, which occupies extended surface areas encircling the gp1 octamer, indicating that DNA wraps around gp1 through extensive contacts. High-resolution structures reveal large-scale motions of the gp1 DNA-binding domain mediated by the curved helix formed by residues 54-81 and an intermolecular salt bridge formed by residues Arg67 and Glu73, indicating remarkable structural plasticity underlying multivalent, pleomorphic gp1:DNA interactions. These results provide spatial restraints for protein:DNA interactions, which enable construction of a three-dimensional pseudo-atomic model for a DNA-packaging initiation complex assembled from the terminase small subunit and the packaging region on viral DNA. Our results suggest that gp1 functions as a DNA-spooling device, which may transform DNA into a specific architecture appropriate for interaction with and cleavage by the terminase large subunit prior to DNA translocation into viral procapsid. This may represent a common mechanism for the initiation step of DNA packaging in tailed double-stranded DNA bacterial viruses.
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Affiliation(s)
- Haiyan Zhao
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
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24
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Roy A, Bhardwaj A, Datta P, Lander GC, Cingolani G. Small terminase couples viral DNA binding to genome-packaging ATPase activity. Structure 2012; 20:1403-13. [PMID: 22771211 DOI: 10.1016/j.str.2012.05.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Revised: 04/30/2012] [Accepted: 05/19/2012] [Indexed: 11/26/2022]
Abstract
Packaging of viral genomes into empty procapsids is powered by a large DNA-packaging motor. In most viruses, this machine is composed of a large (L) and a small (S) terminase subunit complexed with a dodecamer of portal protein. Here we describe the 1.75 Å crystal structure of the bacteriophage P22 S-terminase in a nonameric conformation. The structure presents a central channel ∼23 Å in diameter, sufficiently large to accommodate hydrated B-DNA. The last 23 residues of S-terminase are essential for binding to DNA and assembly to L-terminase. Upon binding to its own DNA, S-terminase functions as a specific activator of L-terminase ATPase activity. The DNA-dependent stimulation of ATPase activity thus rationalizes the exclusive specificity of genome-packaging motors for viral DNA in the crowd of host DNA, ensuring fidelity of packaging and avoiding wasteful ATP hydrolysis. This posits a model for DNA-dependent activation of genome-packaging motors of general interest in virology.
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Affiliation(s)
- Ankoor Roy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, USA
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25
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Abstract
Packaging of viral genomes into preformed procapsids requires the controlled and synchronized activity of an ATPase and a genome-processing nuclease, both located in the large terminase (L-terminase) subunit. In this paper, we have characterized the structure and regulation of bacteriophage P22 L-terminase (gp2). Limited proteolysis reveals a bipartite organization consisting of an N-terminal ATPase core flexibly connected to a C-terminal nuclease domain. The 2.02 Å crystal structure of P22 headful nuclease obtained by in-drop proteolysis of full-length L-terminase (FL-L-terminase) reveals a central seven-stranded β-sheet core that harbors two magnesium ions. Modeling studies with DNA suggest that the two ions are poised for two-metal ion-dependent catalysis, but the nuclease DNA binding surface is sterically hindered by a loop-helix (L(1)-α(2)) motif, which is incompatible with catalysis. Accordingly, the isolated nuclease is completely inactive in vitro, whereas it exhibits endonucleolytic activity in the context of FL-L-terminase. Deleting the autoinhibitory L(1)-α(2) motif (or just the loop L(1)) restores nuclease activity to a level comparable with FL-L-terminase. Together, these results suggest that the activity of P22 headful nuclease is regulated by intramolecular cross-talk with the N-terminal ATPase domain. This cross-talk allows for precise and controlled cleavage of DNA that is essential for genome packaging.
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Affiliation(s)
- Ankoor Roy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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26
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Portal-large terminase interactions of the bacteriophage T4 DNA packaging machine implicate a molecular lever mechanism for coupling ATPase to DNA translocation. J Virol 2012; 86:4046-57. [PMID: 22345478 DOI: 10.1128/jvi.07197-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
DNA packaging by double-stranded DNA bacteriophages and herpesviruses is driven by a powerful molecular machine assembled at the portal vertex of the empty prohead. The phage T4 packaging machine consists of three components: dodecameric portal (gp20), pentameric large terminase motor (gp17), and 11- or 12-meric small terminase (gp16). These components dynamically interact and orchestrate a complex series of reactions to produce a DNA-filled head containing one viral genome per head. Here, we analyzed the interactions between the portal and motor proteins using a direct binding assay, mutagenesis, and structural analyses. Our results show that a portal binding site is located in the ATP hydrolysis-controlling subdomain II of gp17. Mutations at key residues of this site lead to temperature-sensitive or null phenotypes. A conserved helix-turn-helix (HLH) that is part of this site interacts with the portal. A recombinant HLH peptide competes with gp17 for portal binding and blocks DNA translocation. The helices apparently provide specificity to capture the cognate prohead, whereas the loop residues communicate the portal interaction to the ATPase center. These observations lead to a hypothesis in which a unique HLH-portal interaction in the symmetrically mismatched complex acts as a lever to position the arginine finger and trigger ATP hydrolysis. Transiently connecting the critical parts of the motor; subdomain I (ATP binding), subdomain II (controlling ATP hydrolysis), and C-domain (DNA movement), the portal-motor interactions might ensure tight coupling between ATP hydrolysis and DNA translocation.
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27
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Häuser R, Blasche S, Dokland T, Haggård-Ljungquist E, von Brunn A, Salas M, Casjens S, Molineux I, Uetz P. Bacteriophage protein-protein interactions. Adv Virus Res 2012; 83:219-98. [PMID: 22748812 PMCID: PMC3461333 DOI: 10.1016/b978-0-12-394438-2.00006-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Bacteriophages T7, λ, P22, and P2/P4 (from Escherichia coli), as well as ϕ29 (from Bacillus subtilis), are among the best-studied bacterial viruses. This chapter summarizes published protein interaction data of intraviral protein interactions, as well as known phage-host protein interactions of these phages retrieved from the literature. We also review the published results of comprehensive protein interaction analyses of Pneumococcus phages Dp-1 and Cp-1, as well as coliphages λ and T7. For example, the ≈55 proteins encoded by the T7 genome are connected by ≈43 interactions with another ≈15 between the phage and its host. The chapter compiles published interactions for the well-studied phages λ (33 intra-phage/22 phage-host), P22 (38/9), P2/P4 (14/3), and ϕ29 (20/2). We discuss whether different interaction patterns reflect different phage lifestyles or whether they may be artifacts of sampling. Phages that infect the same host can interact with different host target proteins, as exemplified by E. coli phage λ and T7. Despite decades of intensive investigation, only a fraction of these phage interactomes are known. Technical limitations and a lack of depth in many studies explain the gaps in our knowledge. Strategies to complete current interactome maps are described. Although limited space precludes detailed overviews of phage molecular biology, this compilation will allow future studies to put interaction data into the context of phage biology.
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Affiliation(s)
- Roman Häuser
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Sonja Blasche
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Terje Dokland
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Albrecht von Brunn
- Max-von-Pettenkofer-Institut, Lehrstuhl Virologie, Ludwig-Maximilians-Universität, München, Germany
| | - Margarita Salas
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Cantoblanco, Madrid, Spain
| | - Sherwood Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah
| | - Ian Molineux
- Molecular Genetics and Microbiology, Institute for Cell and Molecular Biology, University of Texas–Austin, Austin, Texas, USA
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA
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28
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Structure and function of the small terminase component of the DNA packaging machine in T4-like bacteriophages. Proc Natl Acad Sci U S A 2011; 109:817-22. [PMID: 22207623 DOI: 10.1073/pnas.1110224109] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Tailed DNA bacteriophages assemble empty procapsids that are subsequently filled with the viral genome by means of a DNA packaging machine situated at a special fivefold vertex. The packaging machine consists of a "small terminase" and a "large terminase" component. One of the functions of the small terminase is to initiate packaging of the viral genome, whereas the large terminase is responsible for the ATP-powered translocation of DNA. The small terminase subunit has three domains, an N-terminal DNA-binding domain, a central oligomerization domain, and a C-terminal domain for interacting with the large terminase. Here we report structures of the central domain in two different oligomerization states for a small terminase from the T4 family of phages. In addition, we report biochemical studies that establish the function for each of the small terminase domains. On the basis of the structural and biochemical information, we propose a model for DNA packaging initiation.
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29
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Structural basis for DNA recognition and loading into a viral packaging motor. Proc Natl Acad Sci U S A 2011; 109:811-6. [PMID: 22207627 DOI: 10.1073/pnas.1110270109] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genome packaging into preformed viral procapsids is driven by powerful molecular motors. The small terminase protein is essential for the initial recognition of viral DNA and regulates the motor's ATPase and nuclease activities during DNA translocation. The crystal structure of a full-length small terminase protein from the Siphoviridae bacteriophage SF6, comprising the N-terminal DNA binding, the oligomerization core, and the C-terminal β-barrel domains, reveals a nine-subunit circular assembly in which the DNA-binding domains are arranged around the oligomerization core in a highly flexible manner. Mass spectrometry analysis and four further crystal structures show that, although the full-length protein exclusively forms nine-subunit assemblies, protein constructs missing the C-terminal β-barrel form both nine-subunit and ten-subunit assemblies, indicating the importance of the C terminus for defining the oligomeric state. The mechanism by which a ring-shaped small terminase oligomer binds viral DNA has not previously been elucidated. Here, we probed binding in vitro by using EPR and surface plasmon resonance experiments, which indicated that interaction with DNA is mediated exclusively by the DNA-binding domains and suggested a nucleosome-like model in which DNA binds around the outside of the protein oligomer.
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30
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Abstract
Tailed bacteriophages use nanomotors, or molecular machines that convert chemical energy into physical movement of molecules, to insert their double-stranded DNA genomes into virus particles. These viral nanomotors are powered by ATP hydrolysis and pump the DNA into a preformed protein container called a procapsid. As a result, the virions contain very highly compacted chromosomes. Here, I review recent progress in obtaining structural information for virions, procapsids and the individual motor protein components, and discuss single-molecule in vitro packaging reactions, which have yielded important new information about the mechanism by which these powerful molecular machines translocate DNA.
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31
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Roy A, Bhardwaj A, Cingolani G. Crystallization of the nonameric small terminase subunit of bacteriophage P22. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:104-10. [PMID: 21206037 PMCID: PMC3079985 DOI: 10.1107/s174430911004697x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 11/12/2010] [Indexed: 11/11/2022]
Abstract
The packaging of viral genomes into preformed empty procapsids is powered by an ATP-dependent genome-translocating motor. This molecular machine is formed by a heterodimer consisting of large terminase (L-terminase) and small terminase (S-terminase) subunits, which is assembled into a complex of unknown stoichiometry, and a dodecameric portal protein. There is considerable confusion in the literature regarding the biologically relevant oligomeric state of terminases, which, like portal proteins, form ring-like structures. The number of subunits in a hollow oligomeric protein defines the internal diameter of the central channel and the ability to fit DNA inside. Thus, knowledge of the exact stoichiometry of terminases is critical to decipher the mechanisms of terminase-dependent DNA translocation. Here, the gene encoding bacteriophage P22 S-terminase in Escherichia coli has been overexpressed and the protein purified under native conditions. In the absence of detergents and/or denaturants that may cause disassembly of the native oligomer and formation of aberrant rings, it was found that P22 S-terminase assembles into a concentration-independent nonamer of ∼168 kDa. Nonameric S-terminase was crystallized in two different crystal forms at neutral pH. Crystal form I belonged to space group P2(1)2(1)2, with unit-cell parameters a=144.2, b=144.2, c=145.3 Å, and diffracted to 3.0 Å resolution. Crystal form II belonged to space group P2(1), with unit-cell parameters a=76.48, b=100.9, c=89.95 Å, β=93.73°, and diffracted to 1.75 Å resolution. Preliminary crystallographic analysis of crystal form II confirms that the S-terminase crystals contain a nonamer in the asymmetric unit and are suitable for high-resolution structure determination.
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Affiliation(s)
- Ankoor Roy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, USA
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32
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Gao S, Rao VB. Specificity of interactions among the DNA-packaging machine components of T4-related bacteriophages. J Biol Chem 2010; 286:3944-56. [PMID: 21127059 DOI: 10.1074/jbc.m110.196907] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tailed bacteriophages use powerful molecular motors to package the viral genome into a preformed capsid. Packaging at a rate of up to ∼2000 bp/s and generating a power density twice that of an automobile engine, the phage T4 motor is the fastest and most powerful reported to date. Central to DNA packaging are dynamic interactions among the packaging components, capsid (gp23), portal (gp20), motor (gp17, large "terminase"), and regulator (gp16, small terminase), leading to precise orchestration of the packaging process, but the mechanisms are poorly understood. Here we analyzed the interactions between small and large terminases of T4-related phages. Our results show that the gp17 packaging ATPase is maximally stimulated by homologous, but not heterologous, gp16. Multiple interaction sites are identified in both gp16 and gp17. The specificity determinants in gp16 are clustered in the diverged N- and C-terminal domains (regions I-III). Swapping of diverged region(s), such as replacing C-terminal RB49 region III with that of T4, switched ATPase stimulation specificity. Two specificity regions, amino acids 37-52 and 290-315, are identified in or near the gp17-ATPase "transmission" subdomain II. gp16 binding at these sites might cause a conformational change positioning the ATPase-coupling residues into the catalytic pocket, triggering ATP hydrolysis. These results lead to a model in which multiple weak interactions between motor and regulator allow dynamic assembly and disassembly of various packaging complexes, depending on the functional state of the packaging machine. This might be a general mechanism for regulation of the phage packaging machine and other complex molecular machines.
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Affiliation(s)
- Song Gao
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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33
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Serwer P. A hypothesis for bacteriophage DNA packaging motors. Viruses 2010; 2:1821-1843. [PMID: 21994710 PMCID: PMC3185743 DOI: 10.3390/v2091821] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/12/2010] [Accepted: 08/18/2010] [Indexed: 12/29/2022] Open
Abstract
The hypothesis is presented that bacteriophage DNA packaging motors have a cycle comprised of bind/release thermal ratcheting with release-associated DNA pushing via ATP-dependent protein folding. The proposed protein folding occurs in crystallographically observed peptide segments that project into an axial channel of a protein 12-mer (connector) that serves, together with a coaxial ATPase multimer, as the entry portal. The proposed cycle begins when reverse thermal motion causes the connector’s peptide segments to signal the ATPase multimer to bind both ATP and the DNA molecule, thereby producing a dwell phase recently demonstrated by single-molecule procedures. The connector-associated peptide segments activate by transfer of energy from ATP during the dwell. The proposed function of connector/ATPase symmetry mismatches is to reduce thermal noise-induced signaling errors. After a dwell, ATP is cleaved and the DNA molecule released. The activated peptide segments push the released DNA molecule, thereby producing a burst phase recently shown to consist of four mini-bursts. The constraint of four mini-bursts is met by proposing that each mini-burst occurs via pushing by three of the 12 subunits of the connector. If all four mini-bursts occur, the cycle repeats. If the mini-bursts are not completed, a second cycle is superimposed on the first cycle. The existence of the second cycle is based on data recently obtained with bacteriophage T3. When both cycles stall, energy is diverted to expose the DNA molecule to maturation cleavage.
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Affiliation(s)
- Philip Serwer
- Department of Biochemistry, The University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA
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34
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Johnson JE. Virus particle maturation: insights into elegantly programmed nanomachines. Curr Opin Struct Biol 2010; 20:210-6. [PMID: 20149636 PMCID: PMC2854226 DOI: 10.1016/j.sbi.2010.01.004] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Revised: 01/07/2010] [Accepted: 01/08/2010] [Indexed: 10/19/2022]
Abstract
Similar modes of virus maturation have been observed in dsDNA bacteriophages and the structurally related herpes viruses and some type of maturation occur in most animal viruses. Recently a variety of biophysical studies of maturation intermediates of bacteriophages P22, lambda, and HK97 have suggested an energy landscape that drives the transitions and structure-based mechanisms for its formation. Near-atomic resolution models of subunit tertiary structures in an early intermediate of bacteriophage HK97 maturation revealed a remarkable distortion of the secondary structures when compared to the mature particle. Scaffolding proteins may induce the distortion that is maintained by quaternary structure interactions following scaffold release, making the intermediate particle metastable.
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Affiliation(s)
- John E Johnson
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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35
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Teschke CM, Parent KN. 'Let the phage do the work': using the phage P22 coat protein structures as a framework to understand its folding and assembly mutants. Virology 2010; 401:119-30. [PMID: 20236676 DOI: 10.1016/j.virol.2010.02.017] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 02/03/2010] [Accepted: 02/11/2010] [Indexed: 11/17/2022]
Abstract
The amino acid sequence of viral capsid proteins contains information about their folding, structure and self-assembly processes. While some viruses assemble from small preformed oligomers of coat proteins, other viruses such as phage P22 and herpesvirus assemble from monomeric proteins (Fuller and King, 1980; Newcomb et al., 1999). The subunit assembly process is strictly controlled through protein:protein interactions such that icosahedral structures are formed with specific symmetries, rather than aberrant structures. dsDNA viruses commonly assemble by first forming a precursor capsid that serves as a DNA packaging machine (Earnshaw, Hendrix, and King, 1980; Heymann et al., 2003). DNA packaging is accompanied by a conformational transition of the small precursor procapsid into a larger capsid for isometric viruses. Here we highlight the pseudo-atomic structures of phage P22 coat protein and rationalize several decades of data about P22 coat protein folding, assembly and maturation generated from a combination of genetics and biochemistry.
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Affiliation(s)
- Carolyn M Teschke
- Department of Molecular and Cell Biology, 91 N. Eagleville Rd., U-3125, University of Connecticut, Storrs, CT 06269-3125, USA.
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36
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Crystal structure of the DNA-recognition component of the bacterial virus Sf6 genome-packaging machine. Proc Natl Acad Sci U S A 2010; 107:1971-6. [PMID: 20133842 DOI: 10.1073/pnas.0908569107] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In herpesviruses and many bacterial viruses, genome-packaging is a precisely mediated process fulfilled by a virally encoded molecular machine called terminase that consists of two protein components: A DNA-recognition component that defines the specificity for packaged DNA, and a catalytic component that provides energy for the packaging reaction by hydrolyzing ATP. The terminase docks onto the portal protein complex embedded in a single vertex of a preformed viral protein shell called procapsid, and pumps the viral DNA into the procapsid through a conduit formed by the portal. Here we report the 1.65 A resolution structure of the DNA-recognition component gp1 of the Shigella bacteriophage Sf6 genome-packaging machine. The structure reveals a ring-like octamer formed by interweaved protein monomers with a highly extended fold, embracing a tunnel through which DNA may be translocated. The N-terminal DNA-binding domains form the peripheral appendages surrounding the octamer. The central domain contributes to oligomerization through interactions of bundled helices. The C-terminal domain forms a barrel with parallel beta-strands. The structure reveals a common scheme for oligomerization of terminase DNA-recognition components, and provides insights into the role of gp1 in formation of the packaging-competent terminase complex and assembly of the terminase with the portal, in which ring-like protein oligomers stack together to form a continuous channel for viral DNA translocation.
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Sun S, Rao VB, Rossmann MG. Genome packaging in viruses. Curr Opin Struct Biol 2010; 20:114-20. [PMID: 20060706 DOI: 10.1016/j.sbi.2009.12.006] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Revised: 12/11/2009] [Accepted: 12/16/2009] [Indexed: 10/20/2022]
Abstract
Genome packaging is a fundamental process in a viral life cycle. Many viruses assemble preformed capsids into which the genomic material is subsequently packaged. These viruses use a packaging motor protein that is driven by the hydrolysis of ATP to condense the nucleic acids into a confined space. How these motor proteins package viral genomes had been poorly understood until recently, when a few X-ray crystal structures and cryo-electron microscopy (cryo-EM) structures became available. Here we discuss various aspects of genome packaging and compare the mechanisms proposed for packaging motors on the basis of structural information.
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Affiliation(s)
- Siyang Sun
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-2054, USA
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Lander GC, Khayat R, Li R, Prevelige PE, Potter CS, Carragher B, Johnson JE. The P22 tail machine at subnanometer resolution reveals the architecture of an infection conduit. Structure 2009; 17:789-99. [PMID: 19523897 DOI: 10.1016/j.str.2009.04.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/07/2009] [Accepted: 04/11/2009] [Indexed: 01/03/2023]
Abstract
The portal channel is a key component in the life cycle of bacteriophages and herpesviruses. The bacteriophage P22 portal is a 1 megadalton dodecameric oligomer of gp1 that plays key roles in capsid assembly, DNA packaging, assembly of the infection machinery, and DNA ejection. The portal is the nucleation site for the assembly of 39 additional subunits generated from multiple copies of four gene products (gp4, gp10, gp9, and gp26), which together form the multifunctional tail machine. These components are organized with a combination of 12-fold (gp1, gp4), 6-fold (gp10, trimers of gp9), and 3-fold (gp26, gp9) symmetry. Here we present the 3-dimensional structures of the P22 assembly-naive portal formed from expressed subunits (gp1) and the intact tail machine purified from infectious virions. The assembly-naive portal structure exhibits a striking structural similarity to the structures of the portal proteins of SPP1 and phi29 derived from X-ray crystallography.
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Affiliation(s)
- Gabriel C Lander
- National Resource for Automated Molecular Microscopy, The Scripps Institute, La Jolla, CA 92037, USA
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Al-Zahrani AS, Kondabagil K, Gao S, Kelly N, Ghosh-Kumar M, Rao VB. The small terminase, gp16, of bacteriophage T4 is a regulator of the DNA packaging motor. J Biol Chem 2009; 284:24490-500. [PMID: 19561086 DOI: 10.1074/jbc.m109.025007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tailed bacteriophages and herpes viruses use powerful molecular motors to translocate DNA into a preassembled prohead and compact the DNA to near crystalline density. The phage T4 motor, a pentamer of 70-kDa large terminase, gp17, is the fastest and most powerful motor reported to date. gp17 has an ATPase activity that powers DNA translocation and a nuclease activity that cuts concatemeric DNA and generates the termini of viral genome. An 18-kDa small terminase, gp16, is also essential, but its role in DNA packaging is poorly understood. gp16 forms oligomers, most likely octamers, exhibits no enzymatic activities, but stimulates the gp17-ATPase activity, and inhibits the nuclease activity. Extensive mutational and biochemical analyses show that gp16 contains three domains, a central oligomerization domain, and N- and C-terminal domains that are essential for ATPase stimulation. Stimulation occurs not by nucleotide exchange or enhanced ATP binding but by triggering hydrolysis of gp17-bound ATP, a mechanism reminiscent of GTPase-activating proteins. gp16 does not have an arginine finger but its interaction with gp17 seems to position a gp17 arginine finger into the catalytic pocket. gp16 inhibits DNA translocation when gp17 is associated with the prohead. gp16 restricts gp17-nuclease such that the putative packaging initiation cut is made but random cutting is inhibited. These results suggest that the phage T4 packaging machine consists of a motor (gp17) and a regulator (gp16). The gp16 regulator is essential to coordinate the gp17 motor ATPase, translocase, and nuclease activities, otherwise it could be suicidal to the virus.
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Lander GC, Stagg SM, Voss NR, Cheng A, Fellmann D, Pulokas J, Yoshioka C, Irving C, Mulder A, Lau PW, Lyumkis D, Potter CS, Carragher B. Appion: an integrated, database-driven pipeline to facilitate EM image processing. J Struct Biol 2009; 166:95-102. [PMID: 19263523 DOI: 10.1016/j.jsb.2009.01.002] [Citation(s) in RCA: 692] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The use of cryoEM and three-dimensional image reconstruction is becoming increasingly common. Our vision for this technique is to provide a straightforward manner in which users can proceed from raw data to a reliable 3D reconstruction through a pipeline that both facilitates management of the processing steps and makes the results at each step more transparent. Tightly integrated with a relational SQL database, Appion is a modular and transparent pipeline that extends existing software applications and procedures. The user manages and controls the software modules via web-based forms, and all results are similarly available using web-based viewers directly linked to the underlying database, enabling even naive users to quickly deduce the quality of their results. The Appion API was designed with the principle that applications should be compatible with a broad range of specimens and that libraries and routines are modular and extensible. Presented here is a description of the design and architecture of the working Appion pipeline prototype and some results of its use.
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Affiliation(s)
- Gabriel C Lander
- National Resource for Automated Molecular Microscopy, The Scripps Research Institute, CB 129, 10550 North Torrey Pines Rd, La Jolla, CA 92037, USA
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