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Egido JE, Costa AR, Aparicio-Maldonado C, Haas PJ, Brouns SJJ. Mechanisms and clinical importance of bacteriophage resistance. FEMS Microbiol Rev 2021; 46:6374866. [PMID: 34558600 PMCID: PMC8829019 DOI: 10.1093/femsre/fuab048] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/15/2021] [Indexed: 12/24/2022] Open
Abstract
We are in the midst of a golden age of uncovering defense systems against bacteriophages. Apart from the fundamental interest in these defense systems, and revolutionary applications that have been derived from them (e.g. CRISPR-Cas9 and restriction endonucleases), it is unknown how defense systems contribute to resistance formation against bacteriophages in clinical settings. Bacteriophages are now being reconsidered as therapeutic agents against bacterial infections due the emergence of multidrug resistance. However, bacteriophage resistance through defense systems and other means could hinder the development of successful phage-based therapies. Here, we review the current state of the field of bacteriophage defense, highlight the relevance of bacteriophage defense for potential clinical use of bacteriophages as therapeutic agents and suggest new directions of research.
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Affiliation(s)
- Julia E Egido
- Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Ana Rita Costa
- Department of Bionanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands.,Fagenbank, Delft, Netherlands
| | - Cristian Aparicio-Maldonado
- Department of Bionanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands
| | - Pieter-Jan Haas
- Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, Netherlands
| | - Stan J J Brouns
- Department of Bionanoscience, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, Netherlands.,Kavli Institute of Nanoscience, Delft, Netherlands.,Fagenbank, Delft, Netherlands
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2
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Scaling Theory of a Polymer Ejecting from a Cavity into a Semi-Space. Polymers (Basel) 2020; 12:polym12123014. [PMID: 33339450 PMCID: PMC7766115 DOI: 10.3390/polym12123014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 12/23/2022] Open
Abstract
A two-stage model is developed in order to understand the scaling behaviors of single polymers ejecting from a spherical cavity through a nanopore. The dynamics of ejection is derived by balancing the free energy change with the energy dissipation during a process. The ejection velocity is found to vary with the number of monomers in the cavity, m, as mz1/(Nx1D3z1) at the confined stage, and it turns to be m−z2 at the non-confined stage, where N is the chain length and D the cavity diameter. The exponents are shown to be z1=(3ν−1)−1, z2=2ν and x1=1/3, with ν being the Flory exponent. The profile of the velocity is carefully verified by performing Langevin dynamics simulations. The simulations further reveal that, at the starting point, the decreasing of m can be stalled for a good moment. It suggests the existence of a pre-stage that can be explained by using the concept of a classical nucleation theory. By trimming the pre-stage, the ejection time are properly studied by varying N, D, and ϕ0 (the initial volume fraction). The scaling properties of the nucleation time are also analyzed. The results fully support the predictions of the theory. The physical pictures are given for various ejection conditions that cover the entire parameter space.
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3
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Cruz B, Zhu Z, Calderer C, Arsuaga J, Vazquez M. Quantitative Study of the Chiral Organization of the Phage Genome Induced by the Packaging Motor. Biophys J 2020; 118:2103-2116. [PMID: 32353255 PMCID: PMC7203069 DOI: 10.1016/j.bpj.2020.03.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 11/04/2019] [Accepted: 03/16/2020] [Indexed: 12/11/2022] Open
Abstract
Molecular motors that translocate DNA are ubiquitous in nature. During morphogenesis of double-stranded DNA bacteriophages, a molecular motor drives the viral genome inside a protein capsid. Several models have been proposed for the three-dimensional geometry of the packaged genome, but very little is known of the signature of the molecular packaging motor. For instance, biophysical experiments show that in some systems, DNA rotates during the packaging reaction, but most current biophysical models fail to incorporate this property. Furthermore, studies including rotation mechanisms have reached contradictory conclusions. In this study, we compare the geometrical signatures imposed by different possible mechanisms for the packaging motors: rotation, revolution, and rotation with revolution. We used a previously proposed kinetic Monte Carlo model of the motor, combined with Brownian dynamics simulations of DNA to simulate deterministic and stochastic motor models. We find that rotation is necessary for the accumulation of DNA writhe and for the chiral organization of the genome. We observe that although in the initial steps of the packaging reaction, the torsional strain of the genome is released by rotation of the molecule, in the later stages, it is released by the accumulation of writhe. We suggest that the molecular motor plays a key role in determining the final structure of the encapsidated genome in bacteriophages.
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Affiliation(s)
- Brian Cruz
- Department of Mathematics, University of California, Berkeley, California
| | - Zihao Zhu
- Department of Microbiology and Molecular Genetics, University of California at Davis, Davis, California
| | - Carme Calderer
- School of Mathematics, University of Minnesota, Minneapolis, Minnesota
| | - Javier Arsuaga
- Department of Mathematics, University of California at Davis, Davis, California; Department of Molecular and Cellular Biology, University of California at Davis, Davis, California.
| | - Mariel Vazquez
- Department of Microbiology and Molecular Genetics, University of California at Davis, Davis, California; Department of Mathematics, University of California at Davis, Davis, California.
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4
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Linna RP, Suhonen PM, Piili J. Rigidity-induced scale invariance in polymer ejection from capsid. Phys Rev E 2017; 96:052402. [PMID: 29347730 DOI: 10.1103/physreve.96.052402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Indexed: 06/07/2023]
Abstract
While the dynamics of a fully flexible polymer ejecting a capsid through a nanopore has been extensively studied, the ejection dynamics of semiflexible polymers has not been properly characterized. Here we report results from simulations of ejection dynamics of semiflexible polymers ejecting from spherical capsids. Ejections start from strongly confined polymer conformations of constant initial monomer density. We find that, unlike for fully flexible polymers, for semiflexible polymers the force measured at the pore does not show a direct relation to the instantaneous ejection velocity. The cumulative waiting time t(s), that is, the time at which a monomer s exits the capsid the last time, shows a clear change when increasing the polymer rigidity κ. The major part of an ejecting polymer is driven out of the capsid by internal pressure. At the final stage the polymer escapes the capsid by diffusion. For the driven part there is a crossover from essentially exponential growth of t with s of the fully flexible polymers to a scale-invariant form. In addition, a clear dependence of t on polymer length N_{0} was found. These findings combined give the dependence t(s)∝N_{0}^{0.55}s^{1.33} for the strongly rigid polymers. This crossover in dynamics where κ acts as a control parameter is reminiscent of a phase transition. This analogy is further enhanced by our finding a perfect data collapse of t for polymers of different N_{0} and any constant κ.
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Affiliation(s)
- R P Linna
- Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Finland
| | - P M Suhonen
- Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Finland
| | - J Piili
- Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Finland
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5
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Santos-Pérez I, Oksanen HM, Bamford DH, Goñi FM, Reguera D, Abrescia NGA. Membrane-assisted viral DNA ejection. Biochim Biophys Acta Gen Subj 2016; 1861:664-672. [PMID: 27993658 DOI: 10.1016/j.bbagen.2016.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 12/13/2016] [Accepted: 12/15/2016] [Indexed: 11/26/2022]
Abstract
Genome packaging and delivery are fundamental steps in the replication cycle of all viruses. Icosahedral viruses with linear double-stranded DNA (dsDNA) usually package their genome into a preformed, rigid procapsid using the power generated by a virus-encoded packaging ATPase. The pressure and stored energy due to this confinement of DNA at a high density is assumed to drive the initial stages of genome ejection. Membrane-containing icosahedral viruses, such as bacteriophage PRD1, present an additional architectural complexity by enclosing their genome within an internal membrane vesicle. Upon adsorption to a host cell, the PRD1 membrane remodels into a proteo-lipidic tube that provides a conduit for passage of the ejected linear dsDNA through the cell envelope. Based on volume analyses of PRD1 membrane vesicles captured by cryo-electron tomography and modeling of the elastic properties of the vesicle, we propose that the internal membrane makes a crucial and active contribution during infection by maintaining the driving force for DNA ejection and countering the internal turgor pressure of the host. These novel functions extend the role of the PRD1 viral membrane beyond tube formation or the mere physical confinement of the genome. The presence and assistance of an internal membrane might constitute a biological advantage that extends also to other viruses that package their linear dsDNA to high density within an internal vesicle.
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Affiliation(s)
- Isaac Santos-Pérez
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain
| | - Hanna M Oksanen
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, Viikinkaari 9B, 00014, Finland
| | - Dennis H Bamford
- Institute of Biotechnology and Department of Biosciences, Viikki Biocenter, University of Helsinki, P.O. Box 56, Viikinkaari 9B, 00014, Finland
| | - Felix M Goñi
- Unidad de Biofísica (CSIC, UPV/EHU) and Departamento de Bioquímica, Universidad del País Vasco, Bilbao, Spain
| | - David Reguera
- Departament de Física de la Materia Condensada, Facultat de Física, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Nicola G A Abrescia
- Structural Biology Unit, CIC bioGUNE, CIBERehd, Bizkaia Technology Park, 48160 Derio, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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6
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Thomas JA, Benítez Quintana AD, Bosch MA, Coll De Peña A, Aguilera E, Coulibaly A, Wu W, Osier MV, Hudson AO, Weintraub ST, Black LW. Identification of Essential Genes in the Salmonella Phage SPN3US Reveals Novel Insights into Giant Phage Head Structure and Assembly. J Virol 2016; 90:10284-10298. [PMID: 27605673 PMCID: PMC5105663 DOI: 10.1128/jvi.01492-16] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 08/26/2016] [Indexed: 01/20/2023] Open
Abstract
Giant tailed bacterial viruses, or phages, such as Pseudomonas aeruginosa phage ϕKZ, have long genomes packaged into large, atypical virions. Many aspects of ϕKZ and related phage biology are poorly understood, mostly due to the fact that the functions of the majority of their proteins are unknown. We hypothesized that the Salmonella enterica phage SPN3US could be a useful model phage to address this gap in knowledge. The 240-kb SPN3US genome shares a core set of 91 genes with ϕKZ and related phages, ∼61 of which are virion genes, consistent with the expectation that virion complexity is an ancient, conserved feature. Nucleotide sequencing of 18 mutants enabled assignment of 13 genes as essential, information which could not have been determined by sequence-based searches for 11 genes. Proteome analyses of two SPN3US virion protein mutants with knockouts in 64 and 241 provided new insight into the composition and assembly of giant phage heads. The 64 mutant analyses revealed all the genetic determinants required for assembly of the SPN3US head and a likely head-tail joining role for gp64, and its homologs in related phages, due to the tailless-particle phenotype produced. Analyses of the mutation in 241, which encodes an RNA polymerase β subunit, revealed that without this subunit, no other subunits are assembled into the head, and enabled identification of a "missing" β' subunit domain. These findings support SPN3US as an excellent model for giant phage research, laying the groundwork for future analyses of their highly unusual virions, host interactions, and evolution. IMPORTANCE In recent years, there has been a paradigm shift in virology with the realization that extremely large viruses infecting prokaryotes (giant phages) can be found in many environments. A group of phages related to the prototype giant phage ϕKZ are of great interest due to their virions being among the most complex of prokaryotic viruses and their potential for biocontrol and phage therapy applications. Our understanding of the biology of these phages is limited, as a large proportion of their proteins have not been characterized and/or have been deemed putative without any experimental verification. In this study, we analyzed Salmonella phage SPN3US using a combination of genomics, genetics, and proteomics and in doing so revealed new information regarding giant phage head structure and assembly and virion RNA polymerase composition. Our findings demonstrate the suitability of SPN3US as a model phage for the growing group of phages related to ϕKZ.
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Affiliation(s)
- Julie A Thomas
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, New York, USA
| | | | - Martine A Bosch
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, New York, USA
| | - Adriana Coll De Peña
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, New York, USA
| | - Elizabeth Aguilera
- Natural and Physical Sciences, Baltimore City Community College, Baltimore, Maryland, USA
| | - Assitan Coulibaly
- Natural and Physical Sciences, Baltimore City Community College, Baltimore, Maryland, USA
| | - Weimin Wu
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael V Osier
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, New York, USA
| | - André O Hudson
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, New York, USA
| | - Susan T Weintraub
- University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Lindsay W Black
- University of Maryland School of Medicine, Baltimore, Maryland, USA
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7
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Wang C, Sauvageau D, Elias A. Immobilization of Active Bacteriophages on Polyhydroxyalkanoate Surfaces. ACS APPLIED MATERIALS & INTERFACES 2016; 8:1128-38. [PMID: 26741170 DOI: 10.1021/acsami.5b08664] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A rapid, efficient technique for the attachment of bacteriophages (phages) onto polyhydroxyalkanoate (PHA) surfaces has been developed and compared to three reported methods for phage immobilization. Polymer surfaces were modified to facilitate phage attachment using (1) plasma treatment alone, (2) plasma treatment followed by activation by 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), (3) plasma-initiated acrylic acid grafting, or (4) plasma-initiated acrylic acid grafting with activation by EDC and sulfo-NHS. The impact of each method on the surface chemistry of PHA was investigated using contact angle analysis and X-ray photoelectron spectroscopy. Each of the four treatments was shown to result in both increased hydrophilicity and in the modification of the surface functional groups. Modified surfaces were immersed in suspensions of phage T4 for immobilization. The highest level of phage binding was observed for the surfaces modified by plasma treatment alone. The change in chemical bond states observed for surfaces that underwent plasma treatment is suspected to be the cause of the increased binding of active phages. Plasma-treated surfaces were further analyzed through phage-staining and fluorescence microscopy to assess the surface density of immobilized phages and their capacity to capture hosts. The infective capability of attached phages was confirmed by exposing the phage-immobilized surfaces to the host bacteria Escherichia coli in both plaque and infection dynamic assays. Plasma-treated surfaces with immobilized phages displayed higher infectivity than surfaces treated with other methods; in fact, the equivalent initial multiplicity of infection was 2 orders of magnitude greater than with other methods. Control samples - prepared by immersing polymer surfaces in phage suspensions (without prior plasma treatment) - did not show any bacterial growth inhibition, suggesting they did not bind phages from the suspension.
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Affiliation(s)
- Chanchan Wang
- Department of Chemical and Material Engineering, University of Alberta , 9211 116 Street NW, Edmonton, Alberta T6G 1H9, Canada
| | - Dominic Sauvageau
- Department of Chemical and Material Engineering, University of Alberta , 9211 116 Street NW, Edmonton, Alberta T6G 1H9, Canada
| | - Anastasia Elias
- Department of Chemical and Material Engineering, University of Alberta , 9211 116 Street NW, Edmonton, Alberta T6G 1H9, Canada
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8
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Structural remodeling of bacteriophage T4 and host membranes during infection initiation. Proc Natl Acad Sci U S A 2015; 112:E4919-28. [PMID: 26283379 DOI: 10.1073/pnas.1501064112] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The first stages of productive bacteriophage infections of bacterial host cells require efficient adsorption to the cell surface followed by ejection of phage DNA into the host cytoplasm. To achieve this goal, a phage virion must undergo significant structural remodeling. For phage T4, the most obvious change is the contraction of its tail. Here, we use skinny E. coli minicells as a host, along with cryo-electron tomography and mutant phage virions, to visualize key structural intermediates during initiation of T4 infection. We show for the first time that most long tail fibers are folded back against the tail sheath until irreversible adsorption, a feature compatible with the virion randomly walking across the cell surface to find an optimal site for infection. Our data confirm that tail contraction is triggered by structural changes in the baseplate, as intermediates were found with remodeled baseplates and extended tails. After contraction, the tail tube penetrates the host cell periplasm, pausing while it degrades the peptidoglycan layer. Penetration into the host cytoplasm is accompanied by a dramatic local outward curvature of the cytoplasmic membrane as it fuses with the phage tail tip. The baseplate hub protein gp27 and/or the ejected tape measure protein gp29 likely form the transmembrane channel for viral DNA passage into the cell cytoplasm. Building on the wealth of prior biochemical and structural information, this work provides new molecular insights into the mechanistic pathway of T4 phage infection.
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9
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Marion S, Šiber A. Ejecting phage DNA against cellular turgor pressure. Biophys J 2015; 107:1924-1929. [PMID: 25418173 DOI: 10.1016/j.bpj.2014.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 09/01/2014] [Accepted: 09/05/2014] [Indexed: 11/25/2022] Open
Abstract
We examine in vivo ejection of noncondensed DNA from tailed bacteriophages into bacteria. The ejection is dominantly governed by the physical conditions in the bacteria. The confinement of the DNA in the virus capsid only slightly helps the ejection, becoming completely irrelevant during its last stages. A simple calculation based on the premise of condensed DNA in the cell enables us to estimate the maximal bacterial turgor pressure against which the ejection can still be fully realized. The calculated pressure (~5 atm) shows that the ejection of DNA into Gram-negative bacteria could proceed spontaneously, i.e., without the need to invoke active mechanisms.
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10
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Casjens SR, Hendrix RW. Bacteriophage lambda: Early pioneer and still relevant. Virology 2015; 479-480:310-30. [PMID: 25742714 PMCID: PMC4424060 DOI: 10.1016/j.virol.2015.02.010] [Citation(s) in RCA: 173] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/13/2015] [Accepted: 02/05/2015] [Indexed: 12/14/2022]
Abstract
Molecular genetic research on bacteriophage lambda carried out during its golden age from the mid-1950s to mid-1980s was critically important in the attainment of our current understanding of the sophisticated and complex mechanisms by which the expression of genes is controlled, of DNA virus assembly and of the molecular nature of lysogeny. The development of molecular cloning techniques, ironically instigated largely by phage lambda researchers, allowed many phage workers to switch their efforts to other biological systems. Nonetheless, since that time the ongoing study of lambda and its relatives has continued to give important new insights. In this review we give some relevant early history and describe recent developments in understanding the molecular biology of lambda's life cycle.
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Affiliation(s)
- Sherwood R Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Emma Eccles Jones Medical Research Building, 15 North Medical Drive East, Salt Lake City, UT 84112, USA; Biology Department, University of Utah, Salt Lake City, UT 84112, USA.
| | - Roger W Hendrix
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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11
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Lemon-shaped halo archaeal virus His1 with uniform tail but variable capsid structure. Proc Natl Acad Sci U S A 2015; 112:2449-54. [PMID: 25675521 DOI: 10.1073/pnas.1425008112] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lemon-shaped viruses are common in nature but so far have been observed to infect only archaea. Due to their unusual shape, the structures of these viruses are challenging to study and therefore poorly characterized. Here, we have studied haloarchaeal virus His1 using cryo-electron tomography as well as biochemical dissociation. The virions have different sizes, but prove to be extremely stable under various biochemical treatments. Subtomogram averaging of the computationally extracted virions resolved a tail-like structure with a central tail hub density and six tail spikes. Inside the tail there are two cavities and a plug density that separates the tail hub from the interior genome. His1 most likely uses the tail spikes to anchor to host cells and the tail hub to eject the genome, analogous to classic tailed bacteriophages. Upon biochemical treatment that releases the genome, the lemon-shaped virion transforms into an empty tube. Such a dramatic transformation demonstrates that the capsid proteins are capable of undergoing substantial quaternary structural changes, which may occur at different stages of the virus life cycle.
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12
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Common mechanisms of DNA translocation motors in bacteria and viruses using one-way revolution mechanism without rotation. Biotechnol Adv 2015; 32:853-72. [PMID: 24913057 DOI: 10.1016/j.biotechadv.2014.01.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 01/24/2014] [Accepted: 01/25/2014] [Indexed: 12/15/2022]
Abstract
Biomotors were once described into two categories: linear motor and rotation motor. Recently, a third type of biomotor with revolution mechanism without rotation has been discovered. By analogy, rotation resembles the Earth rotating on its axis in a complete cycle every 24h, while revolution resembles the Earth revolving around the Sun one circle per 365 days (see animations http://nanobio.uky.edu/movie.html). The action of revolution that enables a motor free of coiling and torque has solved many puzzles and debates that have occurred throughout the history of viral DNA packaging motor studies. It also settles the discrepancies concerning the structure, stoichiometry, and functioning of DNA translocation motors. This review uses bacteriophages Phi29, HK97, SPP1, P22, T4, and T7 as well as bacterial DNA translocase FtsK and SpoIIIE or the large eukaryotic dsDNA viruses such as mimivirus and vaccinia virus as examples to elucidate the puzzles. These motors use ATPase, some of which have been confirmed to be a hexamer, to revolve around the dsDNA sequentially. ATP binding induces conformational change and possibly an entropy alteration in ATPase to a high affinity toward dsDNA; but ATP hydrolysis triggers another entropic and conformational change in ATPase to a low affinity for DNA, by which dsDNA is pushed toward an adjacent ATPase subunit. The rotation and revolution mechanisms can be distinguished by the size of channel: the channels of rotation motors are equal to or smaller than 2 nm, that is the size of dsDNA, whereas channels of revolution motors are larger than 3 nm. Rotation motors use parallel threads to operate with a right-handed channel, while revolution motors use a left-handed channel to drive the right-handed DNA in an anti-chiral arrangement. Coordination of several vector factors in the same direction makes viral DNA-packaging motors unusually powerful and effective. Revolution mechanism that avoids DNA coiling in translocating the lengthy genomic dsDNA helix could be advantageous for cell replication such as bacterial binary fission and cell mitosis without the need for topoisomerase or helicase to consume additional energy.
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13
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Hirsh AD, Perkins NC. DNA buckling in bacteriophage cavities as a mechanism to aid virus assembly. J Struct Biol 2015; 189:251-8. [PMID: 25613203 DOI: 10.1016/j.jsb.2015.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 01/03/2023]
Abstract
While relatively simple biologically, bacteriophages are sophisticated biochemical machines that execute a precise sequence of events during virus assembly, DNA packaging, and ejection. These stages of the viral life cycle require intricate coordination of viral components whose structures are being revealed by single molecule experiments and high resolution (cryo-electron microscopy) reconstructions. For example, during packaging, bacteriophages employ some of the strongest known molecular motors to package DNA against increasing pressure within the viral capsid shell. Located upstream of the motor is an elaborate portal system through which DNA is threaded. A high resolution reconstruction of the portal system for bacteriophage ϕ29 reveals that DNA buckles inside a small cavity under large compressive forces. In this study, we demonstrate that DNA can also buckle in other bacteriophages including T7 and P22. Using a computational rod model for DNA, we demonstrate that a DNA buckle can initiate and grow within the small confines of a cavity under biologically-attainable force levels. The forces of DNA-cavity contact and DNA-DNA electrostatic repulsion ultimately limit cavity filling. Despite conforming to very different cavity geometries, the buckled DNA within T7 and P22 exhibits near equal volumetric energy density (∼1kT/nm(3)) and energetic cost of packaging (∼22kT). We hypothesize that a DNA buckle creates large forces on the cavity interior to signal the conformational changes to end packaging. In addition, a DNA buckle may help retain the genome prior to tail assembly through significantly increased contact area with the portal.
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Affiliation(s)
- Andrew D Hirsh
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
| | - N C Perkins
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
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14
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Palyulin VV, Ala-Nissila T, Metzler R. Polymer translocation: the first two decades and the recent diversification. SOFT MATTER 2014; 10:9016-37. [PMID: 25301107 DOI: 10.1039/c4sm01819b] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Probably no other field of statistical physics at the borderline of soft matter and biological physics has caused such a flurry of papers as polymer translocation since the 1994 landmark paper by Bezrukov, Vodyanoy, and Parsegian and the study of Kasianowicz in 1996. Experiments, simulations, and theoretical approaches are still contributing novel insights to date, while no universal consensus on the statistical understanding of polymer translocation has been reached. We here collect the published results, in particular, the famous-infamous debate on the scaling exponents governing the translocation process. We put these results into perspective and discuss where the field is going. In particular, we argue that the phenomenon of polymer translocation is non-universal and highly sensitive to the exact specifications of the models and experiments used towards its analysis.
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Affiliation(s)
- Vladimir V Palyulin
- Institute for Physics & Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany.
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15
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Hanhijärvi KJ, Ziedaite G, Pietilä MK, Hæggström E, Bamford DH. DNA ejection from an archaeal virus--a single-molecule approach. Biophys J 2013; 104:2264-72. [PMID: 23708366 DOI: 10.1016/j.bpj.2013.03.061] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/12/2013] [Accepted: 03/15/2013] [Indexed: 10/26/2022] Open
Abstract
The translocation of genetic material from the viral capsid to the cell is an essential part of the viral infection process. Whether the energetics of this process is driven by the energy stored within the confined nucleic acid or cellular processes pull the genome into the cell has been the subject of discussion. However, in vitro studies of genome ejection have been limited to a few head-tailed bacteriophages with a double-stranded DNA genome. Here we describe a DNA release system that operates in an archaeal virus. This virus infects an archaeon Haloarcula hispanica that was isolated from a hypersaline environment. The DNA-ejection velocity of His1, determined by single-molecule experiments, is comparable to that of bacterial viruses. We found that the ejection process is modulated by the external osmotic pressure (polyethylene glycol (PEG)) and by increased ion (Mg(2+) and Na(+)) concentration. The observed ejection was unidirectional, randomly paused, and incomplete, which suggests that cellular processes are required to complete the DNA transfer.
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Affiliation(s)
- K J Hanhijärvi
- Department of Physics, University of Helsinki, Helsinki, Finland.
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16
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Leavitt JC, Gogokhia L, Gilcrease EB, Bhardwaj A, Cingolani G, Casjens SR. The tip of the tail needle affects the rate of DNA delivery by bacteriophage P22. PLoS One 2013; 8:e70936. [PMID: 23951045 PMCID: PMC3741392 DOI: 10.1371/journal.pone.0070936] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 06/25/2013] [Indexed: 02/01/2023] Open
Abstract
The P22-like bacteriophages have short tails. Their virions bind to their polysaccharide receptors through six trimeric tailspike proteins that surround the tail tip. These short tails also have a trimeric needle protein that extends beyond the tailspikes from the center of the tail tip, in a position that suggests that it should make first contact with the host’s outer membrane during the infection process. The base of the needle serves as a plug that keeps the DNA in the virion, but role of the needle during adsorption and DNA injection is not well understood. Among the P22-like phages are needle types with two completely different C-terminal distal tip domains. In the phage Sf6-type needle, unlike the other P22-type needle, the distal tip folds into a “knob” with a TNF-like fold, similar to the fiber knobs of bacteriophage PRD1 and Adenovirus. The phage HS1 knob is very similar to that of Sf6, and we report here its crystal structure which, like the Sf6 knob, contains three bound L-glutamate molecules. A chimeric P22 phage with a tail needle that contains the HS1 terminal knob efficiently infects the P22 host, Salmonella enterica, suggesting the knob does not confer host specificity. Likewise, mutations that should abrogate the binding of L-glutamate to the needle do not appear to affect virion function, but several different other genetic changes to the tip of the needle slow down potassium release from the host during infection. These findings suggest that the needle plays a role in phage P22 DNA delivery by controlling the kinetics of DNA ejection into the host.
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Affiliation(s)
- Justin C. Leavitt
- Biology Department, University of Utah, Salt Lake City, Utah, United States of America
| | - Lasha Gogokhia
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Eddie B. Gilcrease
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Anshul Bhardwaj
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Sherwood R. Casjens
- Biology Department, University of Utah, Salt Lake City, Utah, United States of America
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
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17
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Petrov AS, Douglas SS, Harvey SC. Effects of pulling forces, osmotic pressure, condensing agents and viscosity on the thermodynamics and kinetics of DNA ejection from bacteriophages to bacterial cells: a computational study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:115101. [PMID: 23399864 PMCID: PMC3705564 DOI: 10.1088/0953-8984/25/11/115101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this work, we report on simulations of double-stranded DNA (dsDNA) ejection from bacteriophage φ29 into a bacterial cell. The ejection was studied with a coarse-grained model, in which viral dsDNA was represented by beads on a torsion-less string. The bacteriophage's capsid and the bacterial cell were defined by sets of spherical constraints. To account for the effects of the viscous medium inside the bacterial cell, the simulations were carried out using a Langevin dynamics protocol. Our simplest simulations (involving constant viscosity and no external biasing forces) produced results compatible with the push-pull model of DNA ejection, with an ejection rate significantly higher in the first part of ejection than in the latter parts. Additionally, we performed more complicated simulations, in which we included additional factors such as external forces, osmotic pressure, condensing agents and ejection-dependent viscosity. The effects of these factors (independently and in combination) on the thermodynamics and kinetics of DNA ejection were studied. We found that, in general, the dependence of ejection forces and ejection rates on the amount of DNA ejected becomes more complex if the ejection is modeled with a broader, more realistic set of parameters and influences (such as variation in the solvent's viscosity and the application of an external force). However, certain combinations of factors and numerical parameters led to the opposition of some ejection-driving and ejection-inhibiting influences, ultimately causing an apparent simplification of the ejection profiles.
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Affiliation(s)
- Anton S Petrov
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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18
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Abstract
Sixty years after Hershey and Chase showed that nucleic acid is the major component of phage particles that is ejected into cells, we still do not fully understand how the process occurs. Advances in electron microscopy have revealed the structure of the condensed DNA confined in a phage capsid, and the mechanisms and energetics of packaging a phage genome are beginning to be better understood. Condensing DNA subjects it to high osmotic pressure, which has been suggested to provide the driving force for its ejection during infection. However, forces internal to a phage capsid cannot, alone, cause complete genome ejection into cells. Here, we describe the structure of the DNA inside mature phages and summarize the current models of genome ejection, both in vitro and in vivo.
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Affiliation(s)
- Ian J Molineux
- Molecular Genetics and Microbiology, Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712, USA.
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19
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Lemay SG, Panja D, Molineux IJ. Role of osmotic and hydrostatic pressures in bacteriophage genome ejection. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 87:022714. [PMID: 23496555 DOI: 10.1103/physreve.87.022714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Indexed: 06/01/2023]
Abstract
A critical step in the bacteriophage life cycle is genome ejection into host bacteria. The ejection process for double-stranded DNA phages has been studied thoroughly in vitro, where after triggering with the cellular receptor the genome ejects into a buffer. The experimental data have been interpreted in terms of the decrease in free energy of the densely packed DNA associated with genome ejection. Here we detail a simple model of genome ejection in terms of the hydrostatic and osmotic pressures inside the phage, a bacterium, and a buffer solution or culture medium. We argue that the hydrodynamic flow associated with the water movement from the buffer solution into the phage capsid and further drainage into the bacterial cytoplasm, driven by the osmotic gradient between the bacterial cytoplasm and culture medium, provides an alternative mechanism for phage genome ejection in vivo; the mechanism is perfectly consistent with phage genome ejection in vitro.
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Affiliation(s)
- Serge G Lemay
- MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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20
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Hernando-Pérez M, Miranda R, Aznar M, Carrascosa JL, Schaap IAT, Reguera D, de Pablo PJ. Direct measurement of phage phi29 stiffness provides evidence of internal pressure. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:2366-70. [PMID: 22648860 DOI: 10.1002/smll.201200664] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Indexed: 05/18/2023]
Abstract
Using AFM nanoindentation experiments, DNA-full phi29 phage capsids are shown to be stiffer than when empty. The presence of counterions softens full viruses in a reversible manner, indicating that pressure originates from the confined DNA. A finite element analysis of the experiments provides an estimate of the pressure of ∼40 atm inside the capsid, which is similar to theoretical predictions.
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21
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Qiu X. Heat induced capsid disassembly and DNA release of bacteriophage λ. PLoS One 2012; 7:e39793. [PMID: 22808062 PMCID: PMC3394758 DOI: 10.1371/journal.pone.0039793] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 05/30/2012] [Indexed: 11/19/2022] Open
Abstract
Successive structural changes of bacteriophage λ upon heating were characterized with quantitative experimental methods. In the commonly used Tris-Mg buffer, differential scanning calorimetry measurements first established that the protein capsid of λ phage melts at 87 °C and its genomic DNA melts at 91 °C. Interestingly, prior to the capsid melting, λDNA was found to escape out of the capsid and subject to DNase digestion above ~68 °C, as concluded from light scattering, UV absorption, and electron microscopy studies. Further investigations indicated distinct temperature-dependent behaviors of the three phage proteins. Around 68 °C, disruption of the tail first occurs and leads to the escape of λ DNA; above the capsid melting temperature of 87 °C, the auxiliary protein gpD of the phage head remains soluble in solution and resists centrifugal sedimentation, whereas the major capsid protein gpE is easily precipitated and likely exists as aggregates.
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Affiliation(s)
- Xiangyun Qiu
- Department of Physics, George Washington University, Washington, DC, United States of America.
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22
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Dhason MS, Wang JCY, Hagan MF, Zlotnick A. Differential assembly of Hepatitis B Virus core protein on single- and double-stranded nucleic acid suggest the dsDNA-filled core is spring-loaded. Virology 2012; 430:20-9. [PMID: 22595445 DOI: 10.1016/j.virol.2012.04.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/08/2012] [Accepted: 04/19/2012] [Indexed: 02/07/2023]
Abstract
Hepatitis B Virus (HBV) cores assemble on viral RNA, which is reverse transcribed within the core to the partially dsDNA genome of mature HBV. However, constraining dsDNA, a stiff polymer, within a core necessarily requires far greater capsid stability than constraining ssRNA. We hypothesized that, unlike ssRNA, dsDNA would be a poor substrate for assembly. We examined titrations of ssDNA and dsDNA with purified HBV core protein, Cp183, by EMSA, EM, DLS, and etheno-DNA fluorescence. Cp183 bound ssDNA with high affinity to form virus-like capsids. However, Cp183 bound dsDNA poorly, forming a mixture of irregular complexes. Nonetheless, we observed some normal cores in dsDNA assembly reactions, indicating that the energy required to bend DNA could be similar to the protein-protein association energy. This similarity of energies suggests that dsDNA stresses mature HBV cores, in agreement with calculation, which may be the basis for the virus maturation signal and DNA release.
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Affiliation(s)
- Mary S Dhason
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
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23
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Speir JA, Johnson JE. Nucleic acid packaging in viruses. Curr Opin Struct Biol 2012; 22:65-71. [PMID: 22277169 DOI: 10.1016/j.sbi.2011.11.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 11/08/2011] [Accepted: 11/09/2011] [Indexed: 10/14/2022]
Abstract
We review recent literature describing protein nucleic acid interactions and nucleic acid organization in viruses. The nature of the viral genome determines its overall organization and its interactions with the capsid protein. Genomes composed of single strand (ss) RNA and DNA are highly flexible and, in some cases, adapt to the symmetry of the particle-forming protein to show repeated, sequence independent, nucleoprotein interactions. Genomes composed of double-stranded (ds) DNA do not interact strongly with the container due to their intrinsic stiffness, but form well-organized layers in virions. Assembly of virions with ssDNA and ssRNA genomes usually occurs through a cooperative condensation of the protein and genome, while dsDNA viruses usually pump the genome into a preformed capsid with a strong, virally encoded, molecular motor complex. We present data that suggest the packing density of ss genomes and ds genomes are comparable, but the latter exhibit far higher pressures due to their stiffness.
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Affiliation(s)
- Jeffrey A Speir
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, United States
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24
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Casjens SR, Molineux IJ. Short noncontractile tail machines: adsorption and DNA delivery by podoviruses. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 726:143-79. [PMID: 22297513 DOI: 10.1007/978-1-4614-0980-9_7] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Tailed dsDNA bacteriophage virions bind to susceptible cells with the tips of their tails and then deliver their DNA through the tail into the cells to initiate infection. This chapter discusses what is known about this process in the short-tailed phages (Podoviridae). Their short tails require that many of these virions adsorb to the outer layers of the cell and work their way down to the outer membrane surface before releasing their DNA. Interestingly, the receptor-binding protein of many short-tailed phages (and some with long tails) has an enzymatic activity that cleaves their polysaccharide receptors. Reversible adsorption and irreversible adsorption to primary and secondary receptors are discussed, including how sequence divergence in tail fiber and tailspike proteins leads to different host specificities. Upon reaching the outer membrane of Gram-negative cells, some podoviral tail machines release virion proteins into the cell that help the DNA efficiently traverse the outer layers of the cell and/or prepare the cell cytoplasm for phage genome arrival. Podoviruses utilize several rather different variations on this theme. The virion DNA is then released into the cell; the energetics of this process is discussed. Phages like T7 and N4 deliver their DNA relatively slowly, using enzymes to pull the genome into the cell. At least in part this mechanism ensures that genes in late-entering DNA are not expressed at early times. On the other hand, phages like P22 probably deliver their DNA more rapidly so that it can be circularized before the cascade of gene expression begins.
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Affiliation(s)
- Sherwood R Casjens
- Pathology Department, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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25
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Davidson AR, Cardarelli L, Pell LG, Radford DR, Maxwell KL. Long noncontractile tail machines of bacteriophages. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 726:115-42. [PMID: 22297512 DOI: 10.1007/978-1-4614-0980-9_6] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this chapter, we describe the structure, assembly, function, and evolution of the long, noncontractile tail of the siphophages, which comprise ∼60% of the phages on earth. We place -particular emphasis on features that are conserved among all siphophages, and trace evolutionary connections between these phages and myophages, which possess long contractile tails. The large number of high-resolution structures of tail proteins solved recently coupled to studies of tail-related complexes by electron microscopy have provided many new insights in this area. In addition, the availability of thousands of phage and prophage genome sequences has allowed the delineation of several large families of tail proteins that were previously unrecognized. We also summarize current knowledge pertaining to the mechanisms by which siphophage tails recognize the bacterial cell surface and mediate DNA injection through the cell envelope. We show that phages infecting Gram-positive and Gram-negative bacteria possess distinct families of proteins at their tail tips that are involved in this process. Finally, we speculate on the evolutionary advantages provided by long phage tails.
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Affiliation(s)
- Alan R Davidson
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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26
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Siber A, Božič AL, Podgornik R. Energies and pressures in viruses: contribution of nonspecific electrostatic interactions. Phys Chem Chem Phys 2011; 14:3746-65. [PMID: 22143065 DOI: 10.1039/c1cp22756d] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We summarize some aspects of electrostatic interactions in the context of viruses. A simplified but, within well defined limitations, reliable approach is used to derive expressions for electrostatic energies and the corresponding osmotic pressures in single-stranded RNA viruses and double-stranded DNA bacteriophages. The two types of viruses differ crucially in the spatial distribution of their genome charge which leads to essential differences in their free energies, depending on the capsid size and total charge in a quite different fashion. Differences in the free energies are trailed by the corresponding characteristics and variations in the osmotic pressure between the inside of the virus and the external bathing solution.
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Abstract
Tailed bacteriophages use nanomotors, or molecular machines that convert chemical energy into physical movement of molecules, to insert their double-stranded DNA genomes into virus particles. These viral nanomotors are powered by ATP hydrolysis and pump the DNA into a preformed protein container called a procapsid. As a result, the virions contain very highly compacted chromosomes. Here, I review recent progress in obtaining structural information for virions, procapsids and the individual motor protein components, and discuss single-molecule in vitro packaging reactions, which have yielded important new information about the mechanism by which these powerful molecular machines translocate DNA.
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28
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Bertin A, de Frutos M, Letellier L. Bacteriophage-host interactions leading to genome internalization. Curr Opin Microbiol 2011; 14:492-6. [PMID: 21783404 DOI: 10.1016/j.mib.2011.07.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 07/02/2011] [Accepted: 07/05/2011] [Indexed: 01/18/2023]
Abstract
Bacteriophage infection is initiated by binding of the virion to a specific receptor located on the host surface. The genome is then released from the capsid and delivered to the host cytoplasm. Our knowledge of these early steps of infection has recently improved. The three-dimensional structure of numerous receptor binding proteins of tailed phages has been solved. Cryo-electron tomography has allowed characterization of the phage-host interactions in a cellular context and at nanometric resolution. The localization and motions of fluorescently labelled phages, receptors and viral DNA were monitored on individual bacteria. Altogether these approaches have revealed the intricacy of these early events and emphasize the link between infection and microbial architecture.
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Affiliation(s)
- Aurélie Bertin
- Institut de Biochimie Biophysique Moléculaire et Cellulaire, Univ Paris-Sud 11, UMR CNRS 8619, F- 91405, Orsay, France
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Visualization of bacteriophage P1 infection by cryo-electron tomography of tiny Escherichia coli. Virology 2011; 417:304-11. [PMID: 21745674 DOI: 10.1016/j.virol.2011.06.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 06/07/2011] [Accepted: 06/08/2011] [Indexed: 11/21/2022]
Abstract
Bacteriophage P1 has a contractile tail that targets the conserved lipopolysaccharide on the outer membrane surface of the host for initial adsorption. The mechanism by which P1 DNA enters the host cell is not well understood, mainly because the transient molecular interactions between bacteriophage and bacteria have been difficult to study by conventional approaches. Here, we engineered tiny E. coli host cells so that the initial stages of P1-host interactions could be captured in unprecedented detail by cryo-electron tomography. Analysis of three-dimensional reconstructions of frozen-hydrated specimens revealed three predominant configurations: an extended tail stage with DNA present in the phage head, a contracted tail stage with DNA, and a contracted tail stage without DNA. Comparative analysis of various conformations indicated that there is uniform penetration of the inner tail tube into the E. coli periplasm and a significant movement of the baseplate away from the outer membrane during tail contraction.
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