1
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Dasgupta S, Thomas JA, Ray K. Mechanism of Viral DNA Packaging in Phage T4 Using Single-Molecule Fluorescence Approaches. Viruses 2024; 16:192. [PMID: 38399968 PMCID: PMC10893049 DOI: 10.3390/v16020192] [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: 12/29/2023] [Revised: 01/19/2024] [Accepted: 01/23/2024] [Indexed: 02/25/2024] Open
Abstract
In all tailed phages, the packaging of the double-stranded genome into the head by a terminase motor complex is an essential step in virion formation. Despite extensive research, there are still major gaps in the understanding of this highly dynamic process and the mechanisms responsible for DNA translocation. Over the last fifteen years, single-molecule fluorescence technologies have been applied to study viral nucleic acid packaging using the robust and flexible T4 in vitro packaging system in conjunction with genetic, biochemical, and structural analyses. In this review, we discuss the novel findings from these studies, including that the T4 genome was determined to be packaged as an elongated loop via the colocalization of dye-labeled DNA termini above the portal structure. Packaging efficiency of the TerL motor was shown to be inherently linked to substrate structure, with packaging stalling at DNA branches. The latter led to the design of multiple experiments whose results all support a proposed torsional compression translocation model to explain substrate packaging. Evidence of substrate compression was derived from FRET and/or smFRET measurements of stalled versus resolvase released dye-labeled Y-DNAs and other dye-labeled substrates relative to motor components. Additionally, active in vivo T4 TerS fluorescent fusion proteins facilitated the application of advanced super-resolution optical microscopy toward the visualization of the initiation of packaging. The formation of twin TerS ring complexes, each expected to be ~15 nm in diameter, supports a double protein ring-DNA synapsis model for the control of packaging initiation, a model that may help explain the variety of ring structures reported among pac site phages. The examination of the dynamics of the T4 packaging motor at the single-molecule level in these studies demonstrates the value of state-of-the-art fluorescent tools for future studies of complex viral replication mechanisms.
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Affiliation(s)
- Souradip Dasgupta
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
| | - Julie A. Thomas
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY 14623, USA;
| | - Krishanu Ray
- Division of Vaccine Research, Institute of Human Virology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA
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2
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Hawkins DEDP, Godwin OC, Antson AA. Viral Genomic DNA Packaging Machinery. Subcell Biochem 2024; 104:181-205. [PMID: 38963488 DOI: 10.1007/978-3-031-58843-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Tailed double-stranded DNA bacteriophage employs a protein terminase motor to package their genome into a preformed protein shell-a system shared with eukaryotic dsDNA viruses such as herpesviruses. DNA packaging motor proteins represent excellent targets for antiviral therapy, with Letermovir, which binds Cytomegalovirus terminase, already licensed as an effective prophylaxis. In the realm of bacterial viruses, these DNA packaging motors comprise three protein constituents: the portal protein, small terminase and large terminase. The portal protein guards the passage of DNA into the preformed protein shell and acts as a protein interaction hub throughout viral assembly. Small terminase recognises the viral DNA and recruits large terminase, which in turn pumps DNA in an ATP-dependent manner. Large terminase also cleaves DNA at the termination of packaging. Multiple high-resolution structures of each component have been resolved for different phages, but it is only more recently that the field has moved towards cryo-EM reconstructions of protein complexes. In conjunction with highly informative single-particle studies of packaging kinetics, these structures have begun to inspire models for the packaging process and its place among other DNA machines.
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Affiliation(s)
- Dorothy E D P Hawkins
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, UK.
| | - Owen C Godwin
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, UK
- Structural Biology, The Francis Crick Institute, London, UK
| | - Alfred A Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, UK.
- Structural Biology, The Francis Crick Institute, London, UK.
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3
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Ge F, Guo R, Liang Y, Chen Y, Shao H, Sung YY, Mok WJ, Wong LL, McMinn A, Wang M. Characterization and genomic analysis of Stutzerimonas stutzeri phage vB_PstS_ZQG1, representing a novel viral genus. Virus Res 2023; 336:199226. [PMID: 37739268 PMCID: PMC10520572 DOI: 10.1016/j.virusres.2023.199226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/11/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
Stutzerimonas stutzeri is an opportunistic pathogenic bacterium belonging to the Gammaproteobacteria, exhibiting wide distribution in the environment and playing significant ecological roles such as nitrogen fixation or pollutant degradation. Despite its ecological importance, only two S. stutzeri phages have been isolated to date. Here, a novel S. stutzeri phage, vB_PstS_ZQG1, was isolated from the surface seawater of Qingdao, China. Transmission electron microscopy analysis indicates that vB_PstS_ZQG1 has a morphology characterized by a long non-contractile tail. The genomic sequence of vB_PstS_ZQG1 contains a linear, double-strand 61,790-bp with the G+C content of 53.24% and encodes 90 putative open reading frames. Two auxiliary metabolic genes encoding TolA protein and nucleotide pyrophosphohydrolase were identified, which are likely involved in host adaptation and phage reproduction. Phylogenetic and comparative genomic analyses demonstrated that vB_PstS_ZQG1 exhibits low similarity with previously isolated phages or uncultured viruses (average nucleotide identity values range from 21.7 to 29.4), suggesting that it represents a novel viral genus by itself, here named as Fuevirus. Biogeographic analysis showed that vB_PstS_ZQG1 was only detected in epipelagic and mesopelagic zone with low abundance. In summary, our findings of the phage vB_PstS_ZQG1 will provide helpful insights for further research on the interactions between S. stutzeri phages and their hosts, and contribute to discovering unknown viral sequences in the metagenomic database.
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Affiliation(s)
- Fuyue Ge
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Ruizhe Guo
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Yantao Liang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Centre for Marine Studies, Qingdao, China.
| | - Ying Chen
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China
| | - Hongbing Shao
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Centre for Marine Studies, Qingdao, China
| | - Yeong Yik Sung
- UMT-OUC Joint Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Wen Jye Mok
- UMT-OUC Joint Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Li Lian Wong
- UMT-OUC Joint Centre for Marine Studies, Qingdao, China; Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Malaysia
| | - Andrew McMinn
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Min Wang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, MoE Laboratory of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Center for Ocean Carbon Neutrality, Ocean University of China, Qingdao, China; UMT-OUC Joint Centre for Marine Studies, Qingdao, China; Haide College, Ocean University of China, Qingdao, China; The Affiliated Hospital of Qingdao University, Qingdao, China.
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4
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Hawkins DEDP, Bayfield O, Fung HKH, Grba DN, Huet A, Conway J, Antson AA. Insights into a viral motor: the structure of the HK97 packaging termination assembly. Nucleic Acids Res 2023; 51:7025-7035. [PMID: 37293963 PMCID: PMC10359639 DOI: 10.1093/nar/gkad480] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 06/10/2023] Open
Abstract
Double-stranded DNA viruses utilise machinery, made of terminase proteins, to package viral DNA into the capsid. For cos bacteriophage, a defined signal, recognised by small terminase, flanks each genome unit. Here we present the first structural data for a cos virus DNA packaging motor, assembled from the bacteriophage HK97 terminase proteins, procapsids encompassing the portal protein, and DNA containing a cos site. The cryo-EM structure is consistent with the packaging termination state adopted after DNA cleavage, with DNA density within the large terminase assembly ending abruptly at the portal protein entrance. Retention of the large terminase complex after cleavage of the short DNA substrate suggests that motor dissociation from the capsid requires headful pressure, in common with pac viruses. Interestingly, the clip domain of the 12-subunit portal protein does not adhere to C12 symmetry, indicating asymmetry induced by binding of the large terminase/DNA. The motor assembly is also highly asymmetric, showing a ring of 5 large terminase monomers, tilted against the portal. Variable degrees of extension between N- and C-terminal domains of individual subunits suggest a mechanism of DNA translocation driven by inter-domain contraction and relaxation.
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Affiliation(s)
- Dorothy E D P Hawkins
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Oliver W Bayfield
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
| | - Herman K H Fung
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117Heidelberg, Germany
| | - Daniel N Grba
- MRC Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Alexis Huet
- Department of Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - James F Conway
- Department of Structural Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Alfred A Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, UK
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5
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Rao VB, Fokine A, Fang Q, Shao Q. Bacteriophage T4 Head: Structure, Assembly, and Genome Packaging. Viruses 2023; 15:527. [PMID: 36851741 PMCID: PMC9958956 DOI: 10.3390/v15020527] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 02/04/2023] [Accepted: 02/06/2023] [Indexed: 02/16/2023] Open
Abstract
Bacteriophage (phage) T4 has served as an extraordinary model to elucidate biological structures and mechanisms. Recent discoveries on the T4 head (capsid) structure, portal vertex, and genome packaging add a significant body of new literature to phage biology. Head structures in unexpanded and expanded conformations show dramatic domain movements, structural remodeling, and a ~70% increase in inner volume while creating high-affinity binding sites for the outer decoration proteins Soc and Hoc. Small changes in intercapsomer interactions modulate angles between capsomer planes, leading to profound alterations in head length. The in situ cryo-EM structure of the symmetry-mismatched portal vertex shows the remarkable structural morphing of local regions of the portal protein, allowing similar interactions with the capsid protein in different structural environments. Conformational changes in these interactions trigger the structural remodeling of capsid protein subunits surrounding the portal vertex, which propagate as a wave of expansion throughout the capsid. A second symmetry mismatch is created when a pentameric packaging motor assembles at the outer "clip" domains of the dodecameric portal vertex. The single-molecule dynamics of the packaging machine suggests a continuous burst mechanism in which the motor subunits adjusted to the shape of the DNA fire ATP hydrolysis, generating speeds as high as 2000 bp/s.
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Affiliation(s)
- Venigalla B. Rao
- Bacteriophage Medical Research Center, Department of Biology, The Catholic University of America, Washington, DC 20064, USA
| | - Andrei Fokine
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Qianglin Fang
- School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen 518107, China
| | - Qianqian Shao
- School of Public Health (Shenzhen), Sun Yat-sen University, Shenzhen 518107, China
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6
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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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7
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Fung HKH, Grimes S, Huet A, Duda RL, Chechik M, Gault J, Robinson C, Hendrix R, Jardine P, Conway J, Baumann C, Antson A. Structural basis of DNA packaging by a ring-type ATPase from an archetypal viral system. Nucleic Acids Res 2022; 50:8719-8732. [PMID: 35947691 PMCID: PMC9410871 DOI: 10.1093/nar/gkac647] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/06/2022] [Accepted: 07/24/2022] [Indexed: 12/24/2022] Open
Abstract
Many essential cellular processes rely on substrate rotation or translocation by a multi-subunit, ring-type NTPase. A large number of double-stranded DNA viruses, including tailed bacteriophages and herpes viruses, use a homomeric ring ATPase to processively translocate viral genomic DNA into procapsids during assembly. Our current understanding of viral DNA packaging comes from three archetypal bacteriophage systems: cos, pac and phi29. Detailed mechanistic understanding exists for pac and phi29, but not for cos. Here, we reconstituted in vitro a cos packaging system based on bacteriophage HK97 and provided a detailed biochemical and structural description. We used a photobleaching-based, single-molecule assay to determine the stoichiometry of the DNA-translocating ATPase large terminase. Crystal structures of the large terminase and DNA-recruiting small terminase, a first for a biochemically defined cos system, reveal mechanistic similarities between cos and pac systems. At the same time, mutational and biochemical analyses indicate a new regulatory mechanism for ATPase multimerization and coordination in the HK97 system. This work therefore establishes a framework for studying the evolutionary relationships between ATP-dependent DNA translocation machineries in double-stranded DNA viruses.
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Affiliation(s)
- Herman K H Fung
- Department of Biology, University of York, York, YO10 5DD, UK
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Shelley Grimes
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alexis Huet
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Robert L Duda
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Maria Chechik
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Joseph Gault
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Paul J Jardine
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - James F Conway
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | | | - Alfred A Antson
- York Structural Biology Laboratory, Department of Chemistry, University of York, York, YO10 5DD, UK
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8
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Heller D, Amaya I, Mohamed A, Ali I, Mavrodi D, Deighan P, Sivanathan V. Systematic overexpression of genes encoded by mycobacteriophage Waterfoul reveals novel inhibitors of mycobacterial growth. G3 (BETHESDA, MD.) 2022; 12:jkac140. [PMID: 35727726 PMCID: PMC9339283 DOI: 10.1093/g3journal/jkac140] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/14/2022] [Indexed: 01/21/2023]
Abstract
Bacteriophages represent an enormous reservoir of novel genes, many of which are unrelated to existing entries in public databases and cannot be assigned a predicted function. Characterization of these genes can provide important insights into the intricacies of phage-host interactions and may offer new strategies to manipulate bacterial growth and behavior. Overexpression is a useful tool in the study of gene-mediated effects, and we describe here the construction of a plasmid-based overexpression library of a complete set of genes for Waterfoul, a mycobacteriophage closely related to those infecting clinically important strains of Mycobacterium tuberculosis and/or Mycobacterium abscessus. The arrayed Waterfoul gene library was systematically screened in a plate-based cytotoxicity assay, identifying a diverse set of 32 Waterfoul gene products capable of inhibiting the growth of the host Mycobacterium smegmatis and providing a first look at the frequency and distribution of cytotoxic products encoded within a single mycobacteriophage genome. Several of these Waterfoul gene products were observed to confer potent anti-mycobacterial effects, making them interesting candidates for follow-up mechanistic studies.
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Affiliation(s)
- Danielle Heller
- Department of Science Education, Howard Hughes Medical Institute, Chevy Chase, MD 20185, USA
| | - Isabel Amaya
- Department of Science Education, Howard Hughes Medical Institute, Chevy Chase, MD 20185, USA
| | - Aleem Mohamed
- Department of Biology, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Ilzat Ali
- Department of Biology, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Dmitri Mavrodi
- Center for Molecular & Cellular Biosciences, University of Southern Mississippi, Hattiesburg, MS 39406, USA
| | - Padraig Deighan
- Department of Biology, Emmanuel College, Boston, MA 02115, USA
| | - Viknesh Sivanathan
- Department of Science Education, Howard Hughes Medical Institute, Chevy Chase, MD 20185, USA
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9
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Dong Y, Zheng K, Zou X, Liang Y, Liu Y, Li X, Shao H, Sung YY, Mok WJ, Wong LL, McMinn A, Wang M. Characterization and Genomic Analysis of the First Podophage Infecting Shewanella, Representing a Novel Viral Cluster. Front Microbiol 2022; 13:853973. [PMID: 35432264 PMCID: PMC9011153 DOI: 10.3389/fmicb.2022.853973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/07/2022] [Indexed: 11/16/2022] Open
Abstract
Shewanella is a common bacterial genus in marine sediments and deep seas, with a variety of metabolic abilities, suggesting its important roles in the marine biogeochemical cycles. In this study, a novel lytic Shewanella phage, vB_SInP-X14, was isolated from the surface coastal waters of Qingdao, China. The vB_SInP-X14 contains a linear, double-strand 36,396-bp with the G + C content of 44.1% and harbors 40 predicted open reading frames. Morphological, growth, and genomic analysis showed that it is the first isolated podovirus infecting Shewanella, with a short propagation time (40 min), which might be resulted from three lytic-related genes. Phylogenetic analysis suggested that vB_SInP-X14 could represent a novel viral genus, named Bocovirus, with four isolated but not classified phages. In addition, 14 uncultured viral genomes assembled from the marine metagenomes could provide additional support to establish this novel viral genus. This study reports the first podovirus infecting Shewanella, establishes a new interaction system for the study of virus–host interactions, and also provides new reference genomes for the marine viral metagenomic analysis.
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Affiliation(s)
- Yue Dong
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
| | - Kaiyang Zheng
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
| | - Xiao Zou
- Qingdao Central Hospital, Qingdao, China
| | - Yantao Liang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
- *Correspondence: Yantao liang,
| | - Yundan Liu
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
| | - Xiang Li
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
| | - Hongbing Shao
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
| | - Yeong Yik Sung
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
- Institute of Marine Biotechnology, Universiti Malaysia Terengganu (UMT), Kuala Nerus, Malaysia
| | - Wen Jye Mok
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
- Institute of Marine Biotechnology, Universiti Malaysia Terengganu (UMT), Kuala Nerus, Malaysia
| | - Li Lian Wong
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
- Institute of Marine Biotechnology, Universiti Malaysia Terengganu (UMT), Kuala Nerus, Malaysia
| | - Andrew McMinn
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Min Wang
- College of Marine Life Sciences, Institute of Evolution and Marine Biodiversity, Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Lab of Polar Oceanography and Global Ocean Change, Ocean University of China, Qingdao, China
- UMT-OUC Joint Center for Marine Studies, Qingdao, China
- The Affiliated Hospital of Qingdao University, Qingdao, China
- Min Wang,
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10
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Abstract
Although the process of genome encapsidation is highly conserved in tailed bacteriophages and eukaryotic double-stranded DNA viruses, there are two distinct packaging pathways that these viruses use to catalyze ATP-driven translocation of the viral genome into a preassembled procapsid shell. One pathway is used by ϕ29-like phages and adenoviruses, which replicate and subsequently package a monomeric, unit-length genome covalently attached to a virus/phage-encoded protein at each 5'-end of the dsDNA genome. In a second, more ubiquitous packaging pathway characterized by phage lambda and the herpesviruses, the viral DNA is replicated as multigenome concatemers linked in a head-to-tail fashion. Genome packaging in these viruses thus requires excision of individual genomes from the concatemer that are then translocated into a preassembled procapsid. Hence, the ATPases that power packaging in these viruses also possess nuclease activities that cut the genome from the concatemer at the beginning and end of packaging. This review focuses on proposed mechanisms of genome packaging in the dsDNA viruses using unit-length ϕ29 and concatemeric λ genome packaging motors as representative model systems.
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Affiliation(s)
- Carlos E Catalano
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, United States.
| | - Marc C Morais
- Department of Biochemistry and Molecular Biology, Sealy Center for Structural and Molecular Biophysics, University of Texas Medical Branch at Galveston, Galveston, TX, United States
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11
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Wangchuk J, Chatterjee A, Patil S, Madugula SK, Kondabagil K. The coevolution of large and small terminases of bacteriophages is a result of purifying selection leading to phenotypic stabilization. Virology 2021; 564:13-25. [PMID: 34598064 DOI: 10.1016/j.virol.2021.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 09/14/2021] [Accepted: 09/14/2021] [Indexed: 10/20/2022]
Abstract
Genome packaging in many dsDNA phages requires a series of precisely coordinated actions of two phage-coded proteins, namely, large terminase (TerL) and small terminase (TerS) with DNA and ATP, and with each other. Despite the strict functional conservation, TerL and TerS homologs exhibit large sequence variations. We investigated the sequence variability across eight phage types and observed a coevolutionary framework wherein the genealogy of TerL homologs mirrored that of the corresponding TerS homologs. Furthermore, a high purifying selection observed (dN/dS«1) indicated strong structural constraints on both TerL and TerS, and identify coevolving residues in TerL and TerS of phage T4 and lambda. Using the highly coevolving (correlation coefficient of 0.99) TerL and TerS of phage N4, we show that their biochemical features are similar to the phylogenetically divergent phage λ terminases. We also demonstrate using the Surface Plasma Resonance (SPR) technique that phage N4 TerL transiently interacts with TerS.
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Affiliation(s)
- Jigme Wangchuk
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Anirvan Chatterjee
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Supriya Patil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Santhosh Kumar Madugula
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India
| | - Kiran Kondabagil
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai, India.
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12
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Inaba H, Ueno T. Artificial bio-nanomachines based on protein needles derived from bacteriophage T4. Biophys Rev 2017; 10:641-658. [PMID: 29147941 DOI: 10.1007/s12551-017-0336-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/07/2017] [Indexed: 12/17/2022] Open
Abstract
Bacteriophage T4 is a natural bio-nanomachine which achieves efficient infection of host cells via cooperative motion of specific three-dimensional protein architectures. The relationships between the protein structures and their dynamic functions have recently been clarified. In this review we summarize the design principles for fabrication of nanomachines using the component proteins of bacteriophage T4 based on these recent advances. We focus on the protein needle known as gp5, which is located at the center of the baseplate at the end of the contractile tail of bacteriophage T4. This protein needle plays a critical role in directly puncturing host cells, and analysis has revealed that it contains a common motif used for cell puncture in other known injection systems, such as T6SS. Our artificial needle based on the β-helical domain of gp5 retains the ability to penetrate cells and can be engineered to deliver various cargos into living cells. Thus, the unique components of bacteriophage T4 and other natural nanomachines have great potential for use as molecular scaffolds in efforts to fabricate new bio-nanomachines.
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Affiliation(s)
- Hiroshi Inaba
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-Minami, Tottori, 680-8552, Japan
| | - Takafumi Ueno
- School of Life Science and Technology, Tokyo Institute of Technology, 4259-B55, Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
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13
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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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14
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Abstract
Translocation of viral double-stranded DNA (dsDNA) into the icosahedral prohead shell is catalyzed by TerL, a motor protein that has ATPase, endonuclease, and translocase activities. TerL, following endonucleolytic cleavage of immature viral DNA concatemer recognized by TerS, assembles into a pentameric ring motor on the prohead's portal vertex and uses ATP hydrolysis energy for DNA translocation. TerL's N-terminal ATPase is connected by a hinge to the C-terminal endonuclease. Inchworm models propose that modest domain motions accompanying ATP hydrolysis are amplified, through changes in electrostatic interactions, into larger movements of the C-terminal domain bound to DNA. In phage ϕ29, four of the five TerL subunits sequentially hydrolyze ATP, each powering translocation of 2.5 bp. After one viral genome is encapsidated, the internal pressure signals termination of packaging and ejection of the motor. Current focus is on the structures of packaging complexes and the dynamics of TerL during DNA packaging, endonuclease regulation, and motor mechanics.
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Affiliation(s)
- Venigalla B Rao
- Department of Biology, The Catholic University of America, Washington, DC 20064;
| | - Michael Feiss
- Department of Microbiology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242;
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15
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Kondabagil K, Dai L, Vafabakhsh R, Ha T, Draper B, Rao VB. Designing a nine cysteine-less DNA packaging motor from bacteriophage T4 reveals new insights into ATPase structure and function. Virology 2014; 468-470:660-668. [PMID: 25443668 DOI: 10.1016/j.virol.2014.08.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 07/31/2014] [Accepted: 08/28/2014] [Indexed: 11/25/2022]
Abstract
The packaging motor of bacteriophage T4 translocates DNA into the capsid at a rate of up to 2000 bp/s. Such a high rate would require coordination of motor movements at millisecond timescale. Designing a cysteine-less gp17 is essential to generate fluorescently labeled motors and measure distance changes between motor domains by FRET analyses. Here, by using sequence alignments, structural modeling, combinatorial mutagenesis, and recombinational rescue, we replaced all nine cysteines of gp17 and introduced single cysteines at defined positions. These mutant motors retained in vitro DNA packaging activity. Single mutant motors translocated DNA molecules in real time as imaged by total internal reflection fluorescence microscopy. We discovered, unexpectedly, that a hydrophobic or nonpolar amino acid next to Walker B motif is essential for motor function, probably for efficient generation of OH(-) nucleophile. The ATPase Walker B motif, thus, may be redefined as "β-strand (4-6 hydrophobic-rich amino acids)-DE-hydrophobic/nonpolar amino acid".
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Affiliation(s)
- Kiran Kondabagil
- Department of Biology, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC, USA
| | - Li Dai
- Department of Biology, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC, USA
| | - Reza Vafabakhsh
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Taekjip Ha
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Howard Hughes Medical Institute, Urbana, IL, USA
| | - Bonnie Draper
- Department of Biology, St. Andrews University, NC, USA
| | - Venigalla B Rao
- Department of Biology, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC, USA.
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16
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Single-molecule packaging initiation in real time by a viral DNA packaging machine from bacteriophage T4. Proc Natl Acad Sci U S A 2014; 111:15096-101. [PMID: 25288726 DOI: 10.1073/pnas.1407235111] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Viral DNA packaging motors are among the most powerful molecular motors known. A variety of structural, biochemical, and single-molecule biophysical approaches have been used to understand their mechanochemistry. However, packaging initiation has been difficult to analyze because of its transient and highly dynamic nature. Here, we developed a single-molecule fluorescence assay that allowed visualization of packaging initiation and reinitiation in real time and quantification of motor assembly and initiation kinetics. We observed that a single bacteriophage T4 packaging machine can package multiple DNA molecules in bursts of activity separated by long pauses, suggesting that it switches between active and quiescent states. Multiple initiation pathways were discovered including, unexpectedly, direct DNA binding to the capsid portal followed by recruitment of motor subunits. Rapid succession of ATP hydrolysis was essential for efficient initiation. These observations have implications for the evolution of icosahedral viruses and regulation of virus assembly.
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17
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Abstract
Bacteriophage T4 is the most well-studied member of Myoviridae, the most complex family of tailed phages. T4 assembly is divided into three independent pathways: the head, the tail and the long tail fibers. The prolate head encapsidates a 172 kbp concatemeric dsDNA genome. The 925 Å-long tail is surrounded by the contractile sheath and ends with a hexagonal baseplate. Six long tail fibers are attached to the baseplate's periphery and are the host cell's recognition sensors. The sheath and the baseplate undergo large conformational changes during infection. X-ray crystallography and cryo-electron microscopy have provided structural information on protein-protein and protein-nucleic acid interactions that regulate conformational changes during assembly and infection of Escherichia coli cells.
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Affiliation(s)
- Moh Lan Yap
- Department of Biological Sciences, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907-2032, USA
| | - Michael G Rossmann
- Department of Biological Sciences, Purdue University, 240 S. Martin Jischke Drive, West Lafayette, IN 47907-2032, USA
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18
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Abstract
Bacteriophage T4 has proven itself readily amenable to phage-based DNA and protein packaging, expression, and display systems due to its physical resiliency and genomic flexibility. As a large dsDNA phage with dispensable internal proteins and dispensable outer capsid proteins it can be adapted to package both DNA and proteins of interest within the capsid and to display peptides and proteins externally on the capsid. A single 170 kb linear DNA, or single or multiple copies of shorter linear DNAs, of any sequence can be packaged by the large terminase subunit in vitro into protein-containing proheads and give full or partially full capsids. The prohead receptacles for DNA packaging can also display peptides or full-length proteins from capsid display proteins HOC and SOC. Our laboratory has also developed a protein expression, packaging, and processing (PEPP) system which we have found to have advantages over mammalian and bacterial cell systems, including high yield, increased stability, and simplified downstream processing. Proteins that we have produced by the phage PEPP platform include human HIV-1 protease, micrococcal endonuclease from Staphylococcus aureus, restriction endonuclease EcoRI, luciferase, human granulocyte colony stimulating factor (GCSF), green fluorescent protein (GFP), and the 99 amino acid C-terminus of amyloid precursor protein (APP). Difficult to produce proteins that are toxic in mammalian protein expression systems are easily produced, packaged, and processed with the PEPP platform. APP is one example of such a highly refractory protein that has been produced successfully. The methods below describe the procedures for in vitro packaging of proheads with DNA and for producing recombinant T4 phage that carry a gene of interest in the phage genome and produce and internally package the corresponding protein of interest.
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19
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Protein interactions in the assembly of the tail of bacteriophage T4. Biophys Rev 2013; 5:79-84. [PMID: 28510165 DOI: 10.1007/s12551-013-0114-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 03/07/2013] [Indexed: 10/26/2022] Open
Abstract
Protein interactions in the assembly of the baseplate have been investigated. The baseplate of the phage T4 tail consists of a hub and six wedges which surround the former. Both reversible and irreversible interactions were found. Reversible association includes gp5 and gp27 (gp: gene product) which form a complex in a pH-dependent manner and gp18 polymerization, i.e. the tail sheath formation depends on the ionic strength. These reversible interactions were followed by irreversible or tight binding which pulls the whole association reaction to complete the assembly. The wedge assembly is strictly ordered which means that if one of the seven wedge proteins is missing, the assembly proceeds to that point and the remaining molecules stay non-associated. The strictly sequential assembly pathway is suggested to be materialized by successive conformational change upon binding, which can be shown by proteolytic probe.
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20
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Zhang H, Schwartz C, De Donatis GM, Guo P. "Push through one-way valve" mechanism of viral DNA packaging. Adv Virus Res 2012; 83:415-65. [PMID: 22748815 DOI: 10.1016/b978-0-12-394438-2.00009-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Double-stranded (ds)DNA viruses package their genomic DNA into a procapsid using a force-generating nanomotor powered by ATP hydrolysis. Viral DNA packaging motors are mainly composed of the connector channel and two DNA packaging enzymes. In 1998, it was proposed that viral DNA packaging motors exercise a mechanism similar to the action of AAA+ ATPases that assemble into ring-shaped oligomers, often hexamers, with a central channel (Guo et al. Molecular Cell, 2:149). This chapter focuses on the most recent findings in the bacteriophage ϕ29 DNA packaging nanomotor to address this intriguing notion. Almost all dsDNA viruses are composed entirely of protein, but in the unique case of ϕ29, packaging RNA (pRNA) plays an intermediate role in the packaging process. Evidence revealed that DNA packaging is accomplished via a "push through one-way valve" mechanism. The ATPase gp16 pushes dsDNA through the connector channel section by section into the procapsid. The dodecameric connector channel functions as a one-way valve that only allows dsDNA to enter but not exit the procapsid during DNA packaging. Although the roles of the ATPase gp16 and the motor connector channel are separate and independent, pRNA bridges these two components to ensure the coordination of an integrated motor. ATP induces a conformational change in gp16, leading to its stronger binding to dsDNA. Furthermore, ATP hydrolysis led to the departure of dsDNA from the ATPase/dsDNA complex, an action used to push dsDNA through the connector channel. It was found unexpectedly that by mutating the basic lysine rings of the connector channel or by changing the pH did not measurably impair DNA translocation or affect the one-way traffic property of the channel, suggesting that the positive charges in the lysine ring are not essential in gearing the dsDNA. The motor channel exercises three discrete, reversible, and controllable steps of gating, with each step altering the channel size by 31% to control the direction of translocation of dsDNA. Many DNA packaging models have been contingent upon the number of base pairs packaged per ATP relative to helical turns for B-type DNA. Both 2 and 2.5 bp per ATP have been used to argue for four, five, or six discrete steps of DNA translocation. The "push through one-way valve" mechanism renews the perception of dsDNA packaging energy calculations and provides insight into the discrepancy between 2 and 2.5 bp per ATP. Application of the DNA packaging motor in nanotechnology and nanomedicine is also addressed. Comparison with nine other DNA packaging models revealed that the "push through one-way valve" is the most agreeable mechanism to interpret most of the findings that led to historical models. The application of viral DNA packaging motors is also discussed.
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Affiliation(s)
- Hui Zhang
- Nanobiotechnology Center, Department of Pharmaceutical Sciences, and Markey Cancer Center, University of Kentucky, Lexington, KY, USA
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21
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Shen X, Li M, Zeng Y, Hu X, Tan Y, Rao X, Jin X, Li S, Zhu J, Zhang K, Hu F. Functional identification of the DNA packaging terminase from Pseudomonas aeruginosa phage PaP3. Arch Virol 2012; 157:2133-41. [PMID: 23011306 PMCID: PMC3488191 DOI: 10.1007/s00705-012-1409-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 05/26/2012] [Indexed: 12/01/2022]
Abstract
Terminase proteins are responsible for DNA recognition and initiation of DNA packaging in phages. We previously reported the genomic sequence of a temperate Pseudomonas aeruginosa phage, PaP3, and determined its precise integration site in the host bacterial chromosome. In this study, we present a detailed functional identification of the DNA packaging terminase for phage PaP3. The purified large subunit p03 was demonstrated to possess ATPase and nuclease activities, as well as the ability to bind to specific DNA when it is unassembled. In addition, a small terminase subunit (p01) of a new type was found and shown to bind specifically to cos-containing DNA and stimulate the cos-cleavage and ATPase activities of p03. The results presented here suggest that PaP3 utilizes a typical cos site mechanism for DNA packaging and provide a first step towards understanding the molecular mechanism of the PaP3 DNA packaging reaction.
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Affiliation(s)
- Xiaodong Shen
- Department of Microbiology, Third Military Medical University, Chongqing, China
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22
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Abstract
The bacteriophage T4 head is an elongated icosahedron packed with 172 kb of linear double-stranded DNA and numerous proteins. The capsid is built from three essential proteins: gp23*, which forms the hexagonal capsid lattice; gp24*, which forms pentamers at 11 of the 12 vertices; and gp20, which forms the unique dodecameric portal vertex through which DNA enters during packaging and exits during infection. Intensive work over more than half a century has led to a deep understanding of the phage T4 head. The atomic structure of gp24 has been determined. A structural model built for gp23 using its similarity to gp24 showed that the phage T4 major capsid protein has the same fold as numerous other icosahedral bacteriophages. However, phage T4 displays an unusual membrane and portal initiated assembly of a shape determining self-sufficient scaffolding core. Folding of gp23 requires the assistance of two chaperones, the Escherichia coli chaperone GroEL acting with the phage-coded gp23-specific cochaperone, gp31. The capsid also contains two nonessential outer capsid proteins, Hoc and Soc, which decorate the capsid surface. Through binding to adjacent gp23 subunits, Soc reinforces the capsid structure. Hoc and Soc have been used extensively in bipartite peptide display libraries and to display pathogen antigens, including those from human immunodeficiency virus (HIV), Neisseria meningitides, Bacillus anthracis, and foot and mouth disease virus. The structure of Ip1*, one of a number of multiple (>100) copy proteins packed and injected with DNA from the full head, shows it to be an inhibitor of one specific restriction endonuclease specifically targeting glycosylated hydroxymethyl cytosine DNA. Extensive mutagenesis, combined with atomic structures of the DNA packaging/terminase proteins gp16 and gp17, elucidated the ATPase and nuclease functional motifs involved in DNA translocation and headful DNA cutting. The cryoelectron microscopy structure of the T4 packaging machine showed a pentameric motor assembled with gp17 subunits on the portal vertex. Single molecule optical tweezers and fluorescence studies showed that the T4 motor packages DNA at the highest rate known and can package multiple segments. Förster resonance energy transfer-fluorescence correlation spectroscopy studies indicate that DNA gets compressed in the stalled motor and that the terminase-to-portal distance changes during translocation. Current evidence suggests a linear two-component (large terminase plus portal) translocation motor in which electrostatic forces generated by ATP hydrolysis drive DNA translocation by alternating the motor between tensed and relaxed states.
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Affiliation(s)
- Lindsay W Black
- Department of Biochemistry and Molecular Biology, University of Maryland Medical School, Baltimore, Maryland, USA
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23
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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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24
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Jiang X, Jiang H, Li C, Wang S, Mi Z, An X, Chen J, Tong Y. Sequence characteristics of T4-like bacteriophage IME08 benome termini revealed by high throughput sequencing. Virol J 2011; 8:194. [PMID: 21524290 PMCID: PMC3105952 DOI: 10.1186/1743-422x-8-194] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 04/27/2011] [Indexed: 11/15/2022] Open
Abstract
Background T4 phage is a model species that has contributed broadly to our understanding of molecular biology. T4 DNA replication and packaging share various mechanisms with human double-stranded DNA viruses such as herpes virus. The literature indicates that T4-like phage genomes have permuted terminal sequences, and are generated by a DNA terminase in a sequence-independent manner; Methods genomic DNA of T4-like bacteriophage IME08 was subjected to high throughput sequencing, and the read sequences with extraordinarily high occurrences were analyzed; Results we demonstrate that both the 5' and 3' termini of the IME08 genome starts with base G or A. The presence of a consensus sequence TTGGA|G around the breakpoint of the high frequency read sequences suggests that the terminase cuts the branched pre-genome in a sequence-preferred manner. Our analysis also shows that terminal cleavage is asymmetric, with one end cut at a consensus sequence, and the other end generated randomly. The sequence-preferred cleavage may produce sticky-ends, but with each end being packaged with different efficiencies; Conclusions this study illustrates how high throughput sequencing can be used to probe replication and packaging mechanisms in bacteriophages and/or viruses.
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Affiliation(s)
- Xiaofang Jiang
- Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
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25
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Zhang Z, Kottadiel VI, Vafabakhsh R, Dai L, Chemla YR, Ha T, Rao VB. A promiscuous DNA packaging machine from bacteriophage T4. PLoS Biol 2011; 9:e1000592. [PMID: 21358801 PMCID: PMC3039672 DOI: 10.1371/journal.pbio.1000592] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 12/30/2010] [Indexed: 11/25/2022] Open
Abstract
Packaged viral genome can be removed from bacteriophage T4 capsid and the capsid refilled with any double-stranded DNA, single or multiple molecules, using a powerful ATP-fueled DNA packaging machine. Complex viruses are assembled from simple protein subunits by sequential and irreversible assembly. During genome packaging in bacteriophages, a powerful molecular motor assembles at the special portal vertex of an empty prohead to initiate packaging. The capsid expands after about 10%–25% of the genome is packaged. When the head is full, the motor cuts the concatemeric DNA and dissociates from the head. Conformational changes, particularly in the portal, are thought to drive these sequential transitions. We found that the phage T4 packaging machine is highly promiscuous, translocating DNA into finished phage heads as well as into proheads. Optical tweezers experiments show that single motors can force exogenous DNA into phage heads at the same rate as into proheads. Single molecule fluorescence measurements demonstrate that phage heads undergo repeated initiations, packaging multiple DNA molecules into the same head. These results suggest that the phage DNA packaging machine has unusual conformational plasticity, powering DNA into an apparently passive capsid receptacle, including the highly stable virus shell, until it is full. These features probably led to the evolution of viral genomes that fit capsid volume, a strikingly common phenomenon in double-stranded DNA viruses, and will potentially allow design of a novel class of nanocapsid delivery vehicles. Phage T4 is a prototype for tailed bacteriophages, the most abundant organisms on the planet, as well as for large eukaryotic viruses such as herpes viruses. These viruses encode powerful machines to package their genomes tightly inside an icosahedral-shaped capsid “head.” Packaging into the capsid occurs via a dodecameric portal, localized in one of the vertexes of the capsid. Packaging requires precise orchestration of a series of steps: assembly of an empty prohead, concatemer cutting and attachment of the motor-DNA complex to the portal vertex, ATP-fueled DNA translocation until the head is full, DNA cutting to terminate packaging, detachment of the motor, and sealing of the packaged head by “neck” assembly. Sequential conformational changes, particularly in the portal, are thought to drive these transitions such that assembly proceeds directionally and irreversibly. Here, we found that the phage T4 packaging machine on various capsids is highly promiscuous, translocating DNA into proheads but also, unexpectedly, into previously filled virus heads. Other studies have shown that in filled viral capsids the structure of the portal is fundamentally altered, and it was thought that the packaging mechanism on full heads would be irreversible. We show that full heads, or heads that are emptied of most of their packaged DNA, can reassemble the packaging machine and use it to re-fill the capsid with any DNA molecules. These results challenge the classic sequential virus assembly models, suggest an explanation for the evolution of viral genomes that fit capsid volume, and point the way to a novel nanocapsid delivery system in which the viral packaging machine (portal and motor) could be used to translocate DNA and other therapeutic molecules into synthetic capsids.
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Affiliation(s)
- Zhihong Zhang
- Department of Biology, The Catholic University of America, Washington, District of Columbia, United States of America
| | - Vishal I. Kottadiel
- Department of Biology, The Catholic University of America, Washington, District of Columbia, United States of America
| | - Reza Vafabakhsh
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Li Dai
- Department of Biology, The Catholic University of America, Washington, District of Columbia, United States of America
| | - Yann R. Chemla
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Taekjip Ha
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Howard Hughes Medical Institute, Urbana, Illinois, United States of America
| | - Venigalla B. Rao
- Department of Biology, The Catholic University of America, Washington, District of Columbia, United States of America
- * E-mail:
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26
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Rao VB, Black LW. Structure and assembly of bacteriophage T4 head. Virol J 2010; 7:356. [PMID: 21129201 PMCID: PMC3012670 DOI: 10.1186/1743-422x-7-356] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 12/03/2010] [Indexed: 12/20/2022] Open
Abstract
The bacteriophage T4 capsid is an elongated icosahedron, 120 nm long and 86 nm wide, and is built with three essential proteins; gp23*, which forms the hexagonal capsid lattice, gp24*, which forms pentamers at eleven of the twelve vertices, and gp20, which forms the unique dodecameric portal vertex through which DNA enters during packaging and exits during infection. The past twenty years of research has greatly elevated the understanding of phage T4 head assembly and DNA packaging. The atomic structure of gp24 has been determined. A structural model built for gp23 using its similarity to gp24 showed that the phage T4 major capsid protein has the same fold as that found in phage HK97 and several other icosahedral bacteriophages. Folding of gp23 requires the assistance of two chaperones, the E. coli chaperone GroEL and the phage coded gp23-specific chaperone, gp31. The capsid also contains two non-essential outer capsid proteins, Hoc and Soc, which decorate the capsid surface. The structure of Soc shows two capsid binding sites which, through binding to adjacent gp23 subunits, reinforce the capsid structure. Hoc and Soc have been extensively used in bipartite peptide display libraries and to display pathogen antigens including those from HIV, Neisseria meningitides, Bacillus anthracis, and FMDV. The structure of Ip1*, one of the components of the core, has been determined, which provided insights on how IPs protect T4 genome against the E. coli nucleases that degrade hydroxymethylated and glycosylated T4 DNA. Extensive mutagenesis combined with the atomic structures of the DNA packaging/terminase proteins gp16 and gp17 elucidated the ATPase and nuclease functional motifs involved in DNA translocation and headful DNA cutting. Cryo-EM structure of the T4 packaging machine showed a pentameric motor assembled with gp17 subunits on the portal vertex. Single molecule optical tweezers and fluorescence studies showed that the T4 motor packages DNA at a rate of up to 2000 bp/sec, the fastest reported to date of any packaging motor. FRET-FCS studies indicate that the DNA gets compressed during the translocation process. The current evidence suggests a mechanism in which electrostatic forces generated by ATP hydrolysis drive the DNA translocation by alternating the motor between tensed and relaxed states.
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Affiliation(s)
- Venigalla B Rao
- Department of Biology, The Catholic University of America, Washington, DC, USA.
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27
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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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28
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Ghosh-Kumar M, Alam TI, Draper B, Stack JD, Rao VB. Regulation by interdomain communication of a headful packaging nuclease from bacteriophage T4. Nucleic Acids Res 2010; 39:2742-55. [PMID: 21109524 PMCID: PMC3074133 DOI: 10.1093/nar/gkq1191] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In genome packaging by tailed bacteriophages and herpesviruses, a concatemeric DNA is cut and inserted into an empty procapsid. A series of cuts follow the encapsidation of each unit-length 'headful' genome, but the mechanisms by which cutting is coupled to packaging are not understood. Here we report the first biochemical characterization of a headful nuclease from bacteriophage T4. Our results show that the T4 nuclease, which resides in the C-terminal domain of large 'terminase' gp17, is a weak endonuclease and regulated by a variety of factors; Mg, NaCl, ATP, small terminase gp16 and N-terminal ATPase domain. The small terminase, which stimulates gp17-ATPase, also stimulates nuclease in the presence of ATP but inhibits in the absence of ATP suggesting interdomain crosstalk. Comparison of the 'relaxed' and 'tensed' states of the motor show that a number of basic residues lining the nuclease groove are positioned to interact with DNA in the tensed state but change their positions in the relaxed state. These results suggest that conformational changes in the ATPase center remodel the nuclease center via an interdomain 'communication track'. This might be a common regulatory mechanism for coupling DNA cutting to DNA packaging among the headful packaging nucleases from dsDNA viruses.
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Affiliation(s)
- Manjira Ghosh-Kumar
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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29
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Lee TJ, Zhang H, Chang CL, Savran C, Guo P. Engineering of the fluorescent-energy-conversion arm of phi29 DNA packaging motor for single-molecule studies. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:2453-9. [PMID: 19743427 PMCID: PMC2837281 DOI: 10.1002/smll.200900467] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The bacteriophage phi29 DNA packaging motor contains a protein core with a central channel comprising twelve copies of re-engineered gp10 protein geared by six copies of packaging RNA (pRNA) and a DNA packaging protein gp16 with unknown copies. Incorporation of this nanomotor into a nanodevice would be beneficial for many applications. To this end, extension and modification of the motor components are necessary for the linkage of this motor to other nanomachines. Here the re-engineering of the motor DNA packaging protein gp16 by extending its length and doubling its size using a fusion protein technique is reported. The modified motor integrated with the eGFP-gp16 maintains the ability to convert the chemical energy from adenosine triphosphate (ATP) hydrolysis to mechanical motion and package DNA. The resulting DNA-filled capsid is subsequently converted into an infectious virion. The extended part of the gp16 arm is a fluorescent protein eGFP, which serves as a marker for tracking the motor in single-molecule studies. The activity of the re-engineered motor with eGFP-gp16 is also observed directly with a bright-field microscope via its ability to transport a 2-microm-sized cargo bound to the DNA.
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Affiliation(s)
- Tae Jin Lee
- Department of Biomedical Engineering, The Vontz Center for Molecular Studies, 3125 Eden Avenue, Room 1301, College of Engineering and College of Medicine, University of Cincinnati, Cincinnati, OH 45267 (USA)
| | - Hui Zhang
- Department of Biomedical Engineering, The Vontz Center for Molecular Studies, 3125 Eden Avenue, Room 1301, College of Engineering and College of Medicine, University of Cincinnati, Cincinnati, OH 45267 (USA)
| | - Chun-Li Chang
- School of Electrical and Computer Engineering, School of Mechanical Engineering, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (USA)
| | - Cagri Savran
- School of Electrical and Computer Engineering, School of Mechanical Engineering, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907 (USA)
| | - Peixuan Guo
- Department of Biomedical Engineering, The Vontz Center for Molecular Studies, 3125 Eden Avenue, Room 1301, College of Engineering and College of Medicine, University of Cincinnati, Cincinnati, OH 45267 (USA)
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30
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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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31
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Abstract
An ATP-powered DNA translocation machine encapsidates the viral genome in the large dsDNA bacteriophages. The essential components include the empty shell, prohead, and the packaging enzyme, terminase. During translocation, terminase is docked on the prohead's portal protein. The translocation ATPase and the concatemer-cutting endonuclease reside in terminase. Remarkably, terminases, portal proteins, and shells of tailed bacteriophages and herpes viruses show conserved features. These DNA viruses may have descended from a common ancestor. Terminase's ATPase consists of a classic nucleotide binding fold, most closely resembling that of monomeric helicases. Intriguing models have been proposed for the mechanism of dsDNA translocation, invoking ATP hydrolysis-driven conformational changes of portal or terminase powering DNA motion. Single-molecule studies show that the packaging motor is fast and powerful. Recent advances permit experiments that can critically test the packaging models. The viral genome translocation mechanism is of general interest, given the parallels between terminases, helicases, and other motor proteins.
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Affiliation(s)
- Venigalla B Rao
- Department of Biology, The Catholic University of America, Washington, D.C. 20064, USA.
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32
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de Andrade Zanotto PM, Krakauer DC. Complete genome viral phylogenies suggests the concerted evolution of regulatory cores and accessory satellites. PLoS One 2008; 3:e3500. [PMID: 18941535 PMCID: PMC2567038 DOI: 10.1371/journal.pone.0003500] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Accepted: 09/17/2008] [Indexed: 11/19/2022] Open
Abstract
We consider the concerted evolution of viral genomes in four families of DNA viruses. Given the high rate of horizontal gene transfer among viruses and their hosts, it is an open question as to how representative particular genes are of the evolutionary history of the complete genome. To address the concerted evolution of viral genes, we compared genomic evolution across four distinct, extant viral families. For all four viral families we constructed DNA-dependent DNA polymerase-based (DdDp) phylogenies and in addition, whole genome sequence, as quantitative descriptions of inter-genome relationships. We found that the history of the polymerase gene was highly predictive of the history of the genome as a whole, which we explain in terms of repeated, co-divergence events of the core DdDp gene accompanied by a number of satellite, accessory genetic loci. We also found that the rate of gene gain in baculovirus and poxviruses proceeds significantly more quickly than the rate of gene loss and that there is convergent acquisition of satellite functions promoting contextual adaptation when distinct viral families infect related hosts. The congruence of the genome and polymerase trees suggests that a large set of viral genes, including polymerase, derive from a phylogenetically conserved core of genes of host origin, secondarily reinforced by gene acquisition from common hosts or co-infecting viruses within the host. A single viral genome can be thought of as a mutualistic network, with the core genes acting as an effective host and the satellite genes as effective symbionts. Larger virus genomes show a greater departure from linkage equilibrium between core and satellites functions.
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33
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Yu TY, Schaefer J. REDOR NMR characterization of DNA packaging in bacteriophage T4. J Mol Biol 2008; 382:1031-42. [PMID: 18703073 PMCID: PMC2633174 DOI: 10.1016/j.jmb.2008.07.077] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 07/20/2008] [Accepted: 07/26/2008] [Indexed: 11/25/2022]
Abstract
Bacteriophage T4 is a large-tailed Escherichia coli virus whose capsid is 120x86 nm. ATP-driven DNA packaging of the T4 capsid results in the loading of a 171-kb genome in less than 5 min during viral infection. We have isolated 50-mg quantities of uniform (15)N- and [epsilon-(15)N]lysine-labeled bacteriophage T4. We have also introduced (15)NH(4)(+) into filled, unlabeled capsids from synthetic medium by exchange. We have examined lyo- and cryoprotected lyophilized T4 using (15)N{(31)P} and (31)P{(15)N} rotational-echo double resonance. The results of these experiments have shown that (i) packaged DNA is in an unperturbed duplex B-form conformation; (ii) the DNA phosphate negative charge is balanced by lysyl amines (3.2%), polyamines (5.8%), and monovalent cations (40%); and (iii) 11% of lysyl amines, 40% of -NH(2) groups of polyamines, and 80% of monovalent cations within the lyophilized T4 capsid are involved in the DNA charge balance. The NMR evidence suggests that DNA enters the T4 capsid in a charge-unbalanced state. We propose that electrostatic interactions may provide free energy to supplement the nanomotor-driven T4 DNA packaging.
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Affiliation(s)
- Tsyr-Yan Yu
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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34
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Alam TI, Draper B, Kondabagil K, Rentas FJ, Ghosh-Kumar M, Sun S, Rossmann MG, Rao VB. The headful packaging nuclease of bacteriophage T4. Mol Microbiol 2008; 69:1180-90. [PMID: 18627466 DOI: 10.1111/j.1365-2958.2008.06344.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Most tailed bacteriophages and herpes viruses replicate genome as a concatemer which is cut by a 'headful' nuclease upon completion of genome packaging. Here, the catalytic centre of phage T4 headful nuclease, present in the C-terminal domain of 'large terminase' gp17, has been defined by mutational, biochemical and structural analyses. The crystal structure shows that this nuclease has an RNase-H fold, suggesting that it cuts DNA by a two-metal ion mechanism. The active centre has a Mg ion co-ordinated by three acidic residues, D401, E458 and D542. Mutations at any of these residues resulted in loss of nuclease activity, but the mutants can package linear DNA. The gp17's nuclease activity is modulated by the 'small terminase', gp16, by the N-terminal ATPase domain of gp17, and by the assembled packaging motor. These results lead to hypotheses concerning how phage headful nucleases cut the viral genomes before and after, but not during, DNA packaging.
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Affiliation(s)
- Tanfis I Alam
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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35
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Oram M, Sabanayagam C, Black LW. Modulation of the packaging reaction of bacteriophage t4 terminase by DNA structure. J Mol Biol 2008; 381:61-72. [PMID: 18586272 DOI: 10.1016/j.jmb.2008.05.074] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 05/27/2008] [Accepted: 05/29/2008] [Indexed: 10/22/2022]
Abstract
Bacteriophage terminases package DNA through the portal ring of a procapsid during phage maturation. We have probed the mechanism of the phage T4 large terminase subunit gp17 by analyzing linear DNAs that are translocated in vitro. Duplex DNAs of random sequence from 20 to 500 bp were efficiently packaged. Dye and short, single-stranded end extensions were tolerated, whereas 20-base extensions, hairpin ends, 20-bp DNA-RNA hybrid, and 4-kb dsRNA substrates were not packaged. Molecules 60 bp long with 10 mismatched bases were translocated; substrates with 20 mismatched bases, a related D-loop structure, or ones with 20-base single-strand regions were not. A single nick in 100- or 200-bp duplexes, irrespective of location, reduced translocation efficiency, but a singly nicked 500-bp molecule was packaged as effectively as an unnicked control. A fluorescence-correlation-spectroscopy-based assay further showed that a 100-bp nicked substrate did not remain stably bound by the terminase-prohead. Taken together, two unbroken DNA strands seem important for packaging, consistent with a proposed torsional compression translocation mechanism.
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Affiliation(s)
- Mark Oram
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 North Greene Street, Baltimore, MD 21201, USA
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36
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Cai Y, Xiao F, Guo P. The effect of N- or C-terminal alterations of the connector of bacteriophage phi29 DNA packaging motor on procapsid assembly, pRNA binding, and DNA packaging. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2008; 4:8-18. [PMID: 18201942 DOI: 10.1016/j.nano.2007.10.084] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 09/27/2007] [Accepted: 10/11/2007] [Indexed: 01/13/2023]
Abstract
Double-stranded DNA viruses package their genomes into procapsids via an ATP-driven nanomotor. This ingenious motor configuration has inspired the development of biomimetics in nanotechnology. Bacteriophage varphi29 DNA-packaging motor has been a popular tool in nanomedicine. To provide information for further motor modification, conjugation, labeling, and manufacturing, the connector protein gp10 of the varphi29 DNA packaging motor was truncated, mutated, and extended. A 25-residue deletion or a 14-residue extension at the C terminus of gp10 did not affect procapsid assembly. A 42-amino acid extension at the N terminus did not interfere with the procapsid assembly but significantly decreased the DNA-packaging efficiency. DNA-packaging activity was restored upon protease cleavage of the extended region. Replacing the N-terminal peptide containing arginine and lysine with a histidine-rich peptide did not affect procapsid assembly but completely inhibited the packaging RNA (pRNA) binding to the connector and hindered subsequent DNA packaging. These results indicate that (1) the N-terminal arginine-lysine residues play a critical role in pRNA binding but are not essential for procapsid assembly; (2) the connector core, but not the flexible N- or C-terminal domains, is responsible for signaling the procapsid assembly; (3) pRNA binds to the connector as a result of electrostatic interactions between the polyanionic nature of nucleic acids and the cationic side groups of the amino acids, similar to RNA binding to Tat or polyArg.
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Affiliation(s)
- Ying Cai
- Department of Biomedical Engineering, The Vontz Center for Molecular Studies, College of Engineering and College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267, USA
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37
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Alam TI, Rao VB. The ATPase domain of the large terminase protein, gp17, from bacteriophage T4 binds DNA: implications to the DNA packaging mechanism. J Mol Biol 2007; 376:1272-81. [PMID: 18234214 DOI: 10.1016/j.jmb.2007.12.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2007] [Revised: 12/14/2007] [Accepted: 12/17/2007] [Indexed: 11/26/2022]
Abstract
Translocation of double-stranded DNA into a preformed capsid by tailed bacteriophages is driven by powerful motors assembled at the special portal vertex. The motor is thought to drive processive cycles of DNA binding, movement, and release to package the viral genome. In phage T4, there is evidence that the large terminase protein, gene product 17 (gp17), assembles into a multisubunit motor and translocates DNA by an inchworm mechanism. gp17 consists of two domains; an N-terminal ATPase domain (amino acids 1-360) that powers translocation of DNA, and a C-terminal nuclease domain (amino acids 361-610) that cuts concatemeric DNA to generate a headful-size viral genome. While the functional motifs of ATPase and nuclease have been well defined and the ATPase atomic structure has been solved, the DNA binding motif(s) responsible for viral DNA recognition, cutting, and translocation are unknown. Here we report the first evidence for the presence of a double-stranded DNA binding activity in the gp17 ATPase domain. Binding to DNA is sensitive to Mg(2+) and salt, but not the type of DNA used. DNA fragments as short as 20 bp can bind to the ATPase but preferential binding was observed to DNA greater than 1 kb. A high molecular weight ATPase-DNA complex was isolated by gel filtration, suggesting oligomerization of ATPase following DNA interaction. DNA binding was not observed with the full-length gp17, or the C-terminal nuclease domain. The small terminase protein, gp16, inhibited DNA binding, which was further accentuated by ATP. The presence of a DNA binding site in the ATPase domain and its binding properties implicate a role in the DNA packaging mechanism.
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Affiliation(s)
- Tanfis I Alam
- Department of Biology, The Catholic University of America, 103 McCort Ward Hall, 620 Michigan Avenue, N.E., Washington, DC 20064, USA
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38
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Abstract
While capsid proteins are assembled around single-stranded genomic DNA or RNA in rod-shaped viruses, the lengthy double-stranded genome of other viruses is packaged forcefully within a preformed protein shell. This entropically unfavourable DNA or RNA packaging is accomplished by an ATP-driven viral nanomotor, which is mainly composed of two components, the oligomerized channel and the packaging enzymes. This intriguing DNA or RNA packaging process has provoked interest among virologists, bacteriologists, biochemists, biophysicists, chemists, structural biologists and computational scientists alike, especially those interested in nanotechnology, nanomedicine, AAA+ family proteins, energy conversion, cell membrane transport, DNA or RNA replication and antiviral therapy. This review mainly focuses on the motors of double-stranded DNA viruses, but double-stranded RNA viral motors are also discussed due to interesting similarities. The novel and ingenious configuration of these nanomotors has inspired the development of biomimetics for nanodevices. Advances in structural and functional studies have increased our understanding of the molecular basis of biological movement to the point where we can begin thinking about possible applications of the viral DNA packaging motor in nanotechnology and medical applications.
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Affiliation(s)
- Peixuan Guo
- Department of Comparative Pathobiology and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.
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39
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Nemecek D, Gilcrease EB, Kang S, Prevelige PE, Casjens S, Thomas GJ. Subunit conformations and assembly states of a DNA-translocating motor: the terminase of bacteriophage P22. J Mol Biol 2007; 374:817-36. [PMID: 17945256 PMCID: PMC2204089 DOI: 10.1016/j.jmb.2007.08.070] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 12/01/2022]
Abstract
Bacteriophage P22, a podovirus infecting strains of Salmonella typhimurium, packages a 42-kbp genome using a headful mechanism. DNA translocation is accomplished by the phage terminase, a powerful molecular motor consisting of large and small subunits. Although many of the structural proteins of the P22 virion have been well characterized, little is known about the terminase subunits and their molecular mechanism of DNA translocation. We report here structural and assembly properties of ectopically expressed and highly purified terminase large and small subunits. The large subunit (gp2), which contains the nuclease and ATPase activities of terminase, exists as a stable monomer with an alpha/beta fold. The small subunit (gp3), which recognizes DNA for packaging and may regulate gp2 activity, exhibits a highly alpha-helical secondary structure and self-associates to form a stable oligomeric ring in solution. For wild-type gp3, the ring contains nine subunits, as demonstrated by hydrodynamic measurements, electron microscopy, and native mass spectrometry. We have also characterized a gp3 mutant (Ala 112-->Thr) that forms a 10-subunit ring, despite a subunit fold indistinguishable from wild type. Both the nonameric and decameric gp3 rings exhibit nonspecific DNA-binding activity, and gp2 is able to bind strongly to the DNA/gp3 complex but not to DNA alone. We propose a scheme for the roles of P22 terminase large and small subunits in the recruitment and packaging of viral DNA and discuss the model in relation to proposals for terminase-driven DNA translocation in other phages.
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Affiliation(s)
- Daniel Nemecek
- School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, MO 64110, USA
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40
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Cuervo A, Vaney MC, Antson AA, Tavares P, Oliveira L. Structural rearrangements between portal protein subunits are essential for viral DNA translocation. J Biol Chem 2007; 282:18907-13. [PMID: 17446176 DOI: 10.1074/jbc.m701808200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transport of DNA into preformed procapsids is a general strategy for genome packing inside virus particles. In most viruses, this task is accomplished by a complex of the viral packaging ATPase with the portal protein assembled at a specialized vertex of the procapsid. Such molecular motor translocates DNA through the central tunnel of the portal protein. A central question to understand this mechanism is whether the portal is a mere conduit for DNA or whether it participates actively on DNA translocation. The most constricted part of the bacteriophage SPP1 portal tunnel is formed by twelve loops, each contributed from one individual subunit. The position of each loop is stabilized by interactions with helix alpha-5, which extends into the portal putative ATPase docking interface. Here, we have engineered intersubunit disulfide bridges between alpha-5s of adjacent portal ring subunits. Such covalent constraint blocked DNA packaging, whereas reduction of the disulfide bridges restored normal packaging activity. DNA exit through the portal in SPP1 virions was unaffected. The data demonstrate that mobility between alpha-5 helices is essential for the mechanism of viral DNA translocation. We propose that the alpha-5 structural rearrangements serve to coordinate ATPase activity with the positions of portal tunnel loops relative to the DNA double helix.
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Affiliation(s)
- Ana Cuervo
- Unité de Virologie Moléculaire et Structurale, Unité Mixte de Recherche (UMR) CNRS 2472, UMR Institut National de la Recherche Agronomique (INRA) 1157 and Institut Fédératif de Recherche 115, 91198 Gif-sur-Yvette Cedex, France
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41
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Sun S, Kondabagil K, Gentz PM, Rossmann MG, Rao VB. The Structure of the ATPase that Powers DNA Packaging into Bacteriophage T4 Procapsids. Mol Cell 2007; 25:943-9. [PMID: 17386269 DOI: 10.1016/j.molcel.2007.02.013] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 01/30/2007] [Accepted: 02/12/2007] [Indexed: 11/20/2022]
Abstract
Packaging the viral genome into empty procapsids, an essential event in the life cycle of tailed bacteriophages and some eukaryotic viruses, is a process that shares features with chromosome assembly. Most viral procapsids possess a special vertex containing a dodecameric portal protein that is used for entry and exit of the viral genome. The portal and an ATPase are parts of the genome-packaging machine. The ATPase is required to provide energy for translocation and compaction of the negative charges on the genomic DNA. Here we report the atomic structure of the ATPase component in a phage DNA-packaging machine. The bacteriophage T4 ATPase has the greatest similarity to monomeric helicases, suggesting that the genome is translocated by an inchworm mechanism. The similarity of the packaging machines in the double-stranded DNA (dsDNA) bacteriophage T4 and dsRNA bacteriophage varphi12 is consistent with the evolution of many virions from a common ancestor.
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Affiliation(s)
- Siyang Sun
- Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907, USA
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42
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Sun J, Cai Y, Moll WD, Guo P. Controlling bacteriophage phi29 DNA-packaging motor by addition or discharge of a peptide at N-terminus of connector protein that interacts with pRNA. Nucleic Acids Res 2006; 34:5482-90. [PMID: 17020922 PMCID: PMC1636484 DOI: 10.1093/nar/gkl701] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacteriophage phi29 utilizes a motor to translocate genomic DNA into a preformed procapsid. The motor contains six pRNAs, an enzyme and one 12-subunit connector with a central channel for DNA transportation. A 20-residue peptide containing a His-tag was fused to the N-terminus of the connector protein gp10. This fusion neither interfered with procapsid assembly nor affected the morphology of the prolate-shaped procapsid. However, the pRNA binding and virion assembly activity were greatly reduced. Such decreased functions can be switched back on by the removal of the tag via protease cleavage, supporting the previous finding that the N-terminus of gp10 is essential for the pRNA binding. The DNA-packaging efficiency with dimeric pRNA was more seriously affected by the extension than with monomeric pRNA. It is speculated that the fusion of the tag generated physical hindrance to pRNA binding, with greater influence for the dimers than the monomers due to their size. These results reveal a potential to turn off and turn on the motor by attaching or removing, respectively, a component to outer part of the motor, and offers an approach for the inhibition of viral replication by using a drug or a small peptide targeted to motor components.
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Affiliation(s)
- Jianhe Sun
- Department of Pathobiology, Purdue Cancer Center and Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN 47907, USA
- School of Agriculture and Biology, Shanghai Jiaotong UniversityShanghai, 201101, People's Republic of China
| | - Ying Cai
- Department of Pathobiology, Purdue Cancer Center and Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN 47907, USA
| | - Wulf-Dieter Moll
- Department of Pathobiology, Purdue Cancer Center and Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN 47907, USA
| | - Peixuan Guo
- Department of Pathobiology, Purdue Cancer Center and Weldon School of Biomedical Engineering, Purdue UniversityWest Lafayette, IN 47907, USA
- To whom correspondence should be addressed at Purdue Cancer Center, B-36 Hansen Life Science Research Building, Purdue University, West Lafayette, IN 47907, USA. Tel: +1 765 494 7561; Fax: +1 765 496 1795;
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43
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Kondabagil KR, Zhang Z, Rao VB. The DNA translocating ATPase of bacteriophage T4 packaging motor. J Mol Biol 2006; 363:786-99. [PMID: 16987527 DOI: 10.1016/j.jmb.2006.08.054] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 08/20/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
In double-stranded DNA bacteriophages the viral DNA is translocated into an empty prohead shell by a powerful ATP-driven motor assembled at the unique portal vertex. Terminases consisting of two to three packaging-related ATPase sites are central to the packaging mechanism. But the nature of the key translocating ATPase, stoichiometry of packaging motor, and basic mechanism of DNA encapsidation are poorly understood. A defined phage T4 packaging system consisting of only two components, proheads and large terminase protein (gp17; 70 kDa), is constructed. Using the large expanded prohead, this system packages any linear double-stranded DNA, including the 171 kb T4 DNA. The small terminase protein, gp16 (18 kDa), is not only not required but also strongly inhibitory. An ATPase activity is stimulated when proheads, gp17, and DNA are actively engaged in the DNA packaging mode. No packaging ATPase was stimulated by the N-terminal gp17-ATPase mutants, K166G (Walker A), D255E (Walker B), E256Q (catalytic carboxylate), D255E-E256D and D255E-E256Q (Walker B and catalytic carboxylate), nor could these sponsor DNA encapsidation. Experiments with the two gp17 domains, N-terminal ATPase domain and C-terminal nuclease domain, suggest that terminase association with the prohead portal and communication between the domains are essential for ATPase stimulation. These data for the first time established an energetic linkage between packaging stimulation of N-terminal ATPase and DNA translocation. A core pathway for the assembly of functional DNA translocating motor is proposed. Since the catalytic motifs of the N-terminal ATPase are highly conserved among >200 large terminase sequences analyzed, these may represent common themes in phage and herpes viral DNA translocation.
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Affiliation(s)
- Kiran R Kondabagil
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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44
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Black LW, Peng G. Mechanistic coupling of bacteriophage T4 DNA packaging to components of the replication-dependent late transcription machinery. J Biol Chem 2006; 281:25635-43. [PMID: 16807240 DOI: 10.1074/jbc.m602093200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulation of the terminal stage of viral DNA development, DNA packaging, is poorly understood. A new phage T4 in vitro DNA packaging assay employed purified proheads, terminase (gp17 + gp16), and ATP to encapsidate DNA resistant to nuclease. Mature phage T4 DNA and linearized plasmid DNAs containing or lacking a cloned T4 gene were packaged with high (approximately 10%) efficiency. Supercoiled, relaxed covalently closed, and nicked circular plasmid DNAs were packaged inefficiently, if at all, by these components. However, efficient packaging is achieved for nicked circular plasmid DNA, but not covalently closed plasmid DNA, upon addition to packaging mixtures of the purified T4 late transcription-replication machinery proteins: gp45 (sliding clamp), gp44/gp62 (clamp loader complex), gp55 (late sigma-factor), and gp33 (transcriptional co-activator). The small terminase subunit (gp16) is inhibitory for packaging linear DNAs, but enhances the transcription-replication protein packaging of nicked plasmid DNA. Taken together with genetic and biochemical evidence of a requirement for gp55 for concatemer packaging to assemble active wild-type phage particles (1), the plasmid packaging results show that initiation of phage T4 packaging on "endless" concatemeric DNA in vivo by terminase depends upon interaction with the DNA loaded gp45 coupled late transcription-replication machinery. The results suggest a close mechanistic connection in vivo between DNA packaging and developmentally concurrent replication-dependent late transcription.
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Affiliation(s)
- Lindsay W Black
- Department of Biochemistry and Molecular Biology, University of Maryland Medical School, Baltimore, Maryland 21201-1503, USA.
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45
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McGeoch DJ, Rixon FJ, Davison AJ. Topics in herpesvirus genomics and evolution. Virus Res 2006; 117:90-104. [PMID: 16490275 DOI: 10.1016/j.virusres.2006.01.002] [Citation(s) in RCA: 353] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 01/04/2006] [Accepted: 01/06/2006] [Indexed: 12/19/2022]
Abstract
Herpesviruses comprise an abundant, widely distributed group of large DNA viruses of humans and other vertebrates, and overall are among the most extensively studied large DNA viruses. Many herpesvirus genome sequences have been determined, and interpreted in terms of gene contents to give detailed views of both ubiquitous and lineage-specific functions. Availability of gene sequences has also enabled evaluations of evolutionary relationships. For herpesviruses of mammals, a robust phylogenetic tree has been constructed, which shows many features characteristic of synchronous development of virus and host lineages over large evolutionary timespans. It has also emerged that three distinct groupings of herpesviruses exist: the first containing viruses with mammals, birds and reptiles as natural hosts; the second containing viruses of amphibians and fish; and the third consisting of a single invertebrate herpesvirus. Within each of the first two groups, the genomes show clear evidence of descent from a common ancestor, but relationships between the three groups are extremely remote. Detailed analyses of capsid structures provide the best evidence for a common origin of the three groups. At a finer level, the structure of the capsid shell protein further suggests an element of common origin between herpesviruses and tailed DNA bacteriophages.
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Affiliation(s)
- Duncan J McGeoch
- Medical Research Council Virology Unit, Institute of Virology, University of Glasgow, Church Street, Glasgow G11 5JR, UK.
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46
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Kondabagil KR, Rao VB. A critical coiled coil motif in the small terminase, gp16, from bacteriophage T4: insights into DNA packaging initiation and assembly of packaging motor. J Mol Biol 2006; 358:67-82. [PMID: 16513134 DOI: 10.1016/j.jmb.2006.01.078] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 01/13/2006] [Accepted: 01/20/2006] [Indexed: 11/25/2022]
Abstract
Double-stranded DNA packaging in bacteriophages is driven by one of the most powerful force-generating molecular motors reported to date. The phage T4 motor is composed of the small terminase protein, gpl6 (18kDa), the large terminase protein, gp17 (70kDa), and the dodecameric portal protein gp20 (61kDa). gp16, which exists as an oligomer in solution, is involved in the recognition of the viral DNA substrate, the very first step in the DNA packaging pathway, and stimulates the ATPase and packaging activities associated with gp17. Sequence analyses using COILS2 revealed the presence of coiled coil motifs (CCMs) in gp16. Sixteen T4-family and numerous phage small terminases show CCMs in the corresponding region of the protein, suggesting a common structural and functional theme. Biochemical properties such as reversible thermal denaturation and analytical gel filtration data suggest that the central CCM-1 is critical for oligomerization of gp16. Mutations in CCM-1 that change the hydrophobicity of key residues, or pH 6.0, destabilized coiled coil interactions, resulting in a loss of gp16 oligomerization. The gp16 oligomers are in a dynamic equilibrium with lower M(r) intermediate species and monomer. Monomeric gp16 is unable to stimulate gp17-ATPase, an activity essential for DNA packaging, while conversion back into oligomeric form restored the activity. These data for the first time defined a CCM that is critical for structure and function of the small terminase. We postulate a packaging model in which the gp16 CCM is implicated in the regulation of packaging initiation and assembly of a supramolecular DNA packaging machine on the viral concatemer.
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Affiliation(s)
- Kiran R Kondabagil
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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47
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Lee TJ, Guo P. Interaction of gp16 with pRNA and DNA for Genome Packaging by the Motor of Bacterial Virus phi29. J Mol Biol 2006; 356:589-99. [PMID: 16376938 DOI: 10.1016/j.jmb.2005.10.045] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 10/12/2005] [Accepted: 10/17/2005] [Indexed: 11/18/2022]
Abstract
One striking feature in the assembly of linear double-stranded (ds) DNA viruses is that their genome is translocated into a preformed protein coat via a motor involving two non-structural components with certain characteristics of ATPase. In bacterial virus phi29, these two components include the protein gp16 and a packaging RNA (pRNA). The structure and function of other phi29 motor components have been well elucidated; however, studies on the role of gp16 have been seriously hampered by its hydrophobicity and self-aggregation. Such problems caused by insolubility also occur in the study of other viral DNA-packaging motors. Contradictory data have been published regarding the role and stoichiometry of gp16, which has been reported to bind every motor component, including pRNA, DNA, gp3, DNA-gp3, connector, pRNA-free procapsid, and procapsid/pRNA complex. Such conflicting data from a binding assay could be due to the self-aggregation of gp16. Our recent advance to produce soluble and highly active gp16 has enabled further studies on gp16. It was demonstrated in this report that gp16 bound to DNA non-specifically. gp16 bound to the pRNA-containing procapsid much more strongly than to the pRNA-free procapsid. The domain of pRNA for gp16 interaction was the 5'/3' paired helical region. The C18C19A20 bulge that is essential for DNA packaging was found to be dispensable for gp16 binding. This result confirms the published model that pRNA binds to the procapsid with its central domain and extends its 5'/3' DNA-packaging domain for gp16 binding. It suggests that gp16 serves as a linkage between pRNA and DNA, and as an essential DNA-contacting component during DNA translocation. The data also imply that, with the exception of the C18C19A20 bulge, the main role of the 5'/3' helical double-stranded region of pRNA is not for procapsid binding but for binding to gp16.
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Affiliation(s)
- Tae-Jin Lee
- Department of Pathobiology, Weldon School of Biomedical Engineering, and Cancer Center, Purdue University, West Lafayette, IN 47907, USA
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48
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Oliveira L, Alonso JC, Tavares P. A defined in vitro system for DNA packaging by the bacteriophage SPP1: insights into the headful packaging mechanism. J Mol Biol 2006; 353:529-39. [PMID: 16194546 DOI: 10.1016/j.jmb.2005.08.063] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 08/26/2005] [Accepted: 08/26/2005] [Indexed: 11/16/2022]
Abstract
Tailed icosahedral bacteriophages and other viruses package their double-stranded DNA inside a preformed procapsid. In a large number of phages packaging is initiated by recognition and cleavage by a viral packaging ATPase (terminase) of the specific pac sequence (pac cleavage), which generates the first DNA end to be encapsidated. A sequence-independent cleavage (headful cleavage) terminates packaging, generating a new starting point for another round of packaging. The molecular mechanisms underlying headful packaging and its processivity remain poorly understood. A defined in vitro DNA packaging system for the headful double-stranded DNA bacteriophage SPP1 is reported. The in vitro system consists of DNA packaging reactions with highly purified terminase and SPP1 procapsids, coupled to a DNase protection assay. The high yield obtained enabled us to quantify directly the efficiency of DNA entry into the procapsids. We show that in vitro DNA packaging requires the presence of both terminase subunits. The SPP1 in vitro system is able to efficiently package mature SPP1 DNA as well as linear plasmid DNAs. In contrast, no DNA packaging could be detected with circular DNA, signifying that in vitro packaging requires free DNA extremities. Finally, we demonstrate that SPP1 in vitro DNA packaging is independent of the pac signal. These findings suggest that the formation of free DNA ends that are generated by pac cleavage in vivo is the rate-limiting step in processive headful DNA packaging.
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Affiliation(s)
- Leonor Oliveira
- Unité de Virologie Moléculaire et Structurale, UMR CNRS 2472, UMR INRA 1157 and IFR 115, Bat. 14B, Avenue de la Terrasse, 91198 Gif-sur-Yvette cedex, France.
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49
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Abstract
Bacterophage T4 consists of three parts, namely, a head, a tail, and six tail fibers, each of which is assembled along an independent pathway and then joined. In contrast to simple plant viruses such as tobacco mosaic virus, disassembly and reassembly of the virion is not possible. This is due mainly to the fact that the assembly involves not only irreversible steps such as cleavage of covalent bonds of some constituent proteins, but also that it requires a scaffold and involves the inner membrane of the host cell. Another unique feature of the assembly as a biological nanomachine is the involvement of specific protein devices such as a "ruler molecule," which determines the length of the tail, an ATP-driven DNA packaging protein complex, and phage-encoded molecular chaperones. Recent structural biological studies of the phage started to unveil the molecular mechanics of structural transformation of the tail upon infection.
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Affiliation(s)
- Fumio Arisaka
- Department of Biomolecular Processing, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259-B39, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
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50
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Abstract
Packaging of double-stranded DNA into bacteriophage capsids is driven by one of the most powerful force-generating motors reported to date. The phage T4 motor is constituted by gene product 16 (gp16) (18 kDa; small terminase), gp17 (70 kDa; large terminase), and gp20 (61 kDa; dodecameric portal). Extensive sequence alignments revealed that numerous phage and viral large terminases encode a common Walker-B motif in the N-terminal ATPase domain. The gp17 motif consists of a highly conserved aspartate (Asp255) preceded by four hydrophobic residues (251MIYI254), which are predicted to form a beta-strand. Combinatorial mutagenesis demonstrated that mutations that compromised hydrophobicity, or integrity of the beta-strand, resulted in a null phenotype, whereas certain changes in hydrophobicity resulted in cs/ts phenotypes. No substitutions, including a highly conservative glutamate, are tolerated at the conserved aspartate. Biochemical analyses revealed that the Asp255 mutants showed no detectable in vitro DNA packaging activity. The purified D255E, D255N, D255T, D255V, and D255E/E256D mutant proteins exhibited defective ATP binding and very low or no gp16-stimulated ATPase activity. The nuclease activity of gp17 is, however, retained, albeit at a greatly reduced level. These data define the N-terminal ATPase center in terminases and show for the first time that subtle defects in the ATP-Mg complex formation at this center lead to a profound loss of phage DNA packaging.
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Affiliation(s)
- Michael S Mitchell
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
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