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Prichard A, Pogliano J. The intricate organizational strategy of nucleus-forming phages. Curr Opin Microbiol 2024; 79:102457. [PMID: 38581914 DOI: 10.1016/j.mib.2024.102457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/01/2024] [Accepted: 03/08/2024] [Indexed: 04/08/2024]
Abstract
Nucleus-forming phages (chimalliviruses) encode numerous genes responsible for creating intricate structures for viral replication. Research on this newly appreciated family of phages has begun to reveal the mechanisms underlying the subcellular organization of the nucleus-based phage replication cycle. These discoveries include the structure of the phage nuclear shell, the identification of a membrane-bound early phage infection intermediate, the dynamic localization of phage RNA polymerases, the phylogeny and core genome of chimalliviruses, and the variation in replication mechanisms across diverse nucleus-forming phages. This research is being propelled forward through the application of fluorescence microscopy and cryo-electron microscopy and the innovative use of new tools such as proximity labeling and RNA-targeting Clustered Regularly Interspaced Short Palindromic Repeats-Cas systems.
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Affiliation(s)
- Amy Prichard
- School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Joe Pogliano
- School of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA.
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2
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Knipe DM, Prichard A, Sharma S, Pogliano J. Replication Compartments of Eukaryotic and Bacterial DNA Viruses: Common Themes Between Different Domains of Host Cells. Annu Rev Virol 2022; 9:307-327. [PMID: 36173697 DOI: 10.1146/annurev-virology-012822-125828] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Subcellular organization is essential for life. Cells organize their functions into organelles to concentrate their machinery and supplies for optimal efficiency. Likewise, viruses organize their replication machinery into compartments or factories within their host cells for optimal replicative efficiency. In this review, we discuss how DNA viruses that infect both eukaryotic cells and bacteria assemble replication compartments for synthesis of progeny viral DNA and transcription of the viral genome. Eukaryotic DNA viruses assemble replication compartments in the nucleus of the host cell while DNA bacteriophages assemble compartments called phage nuclei in the bacterial cytoplasm. Thus, DNA viruses infecting host cells from different domains of life share common replication strategies.
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Affiliation(s)
- David M Knipe
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA;
| | - Amy Prichard
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
| | - Surendra Sharma
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, USA;
| | - Joe Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
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3
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Chaikeeratisak V, Khanna K, Nguyen KT, Egan ME, Enustun E, Armbruster E, Lee J, Pogliano K, Villa E, Pogliano J. Subcellular organization of viral particles during maturation of nucleus-forming jumbo phage. SCIENCE ADVANCES 2022; 8:eabj9670. [PMID: 35507660 PMCID: PMC9067925 DOI: 10.1126/sciadv.abj9670] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 03/16/2022] [Indexed: 06/03/2023]
Abstract
Many eukaryotic viruses assemble mature particles within distinct subcellular compartments, but bacteriophages are generally assumed to assemble randomly throughout the host cell cytoplasm. Here, we show that viral particles of Pseudomonas nucleus-forming jumbo phage PhiPA3 assemble into a unique structure inside cells we term phage bouquets. We show that after capsids complete DNA packaging at the surface of the phage nucleus, tails assemble and attach to capsids, and these particles accumulate over time in a spherical pattern, with tails oriented inward and the heads outward to form bouquets at specific subcellular locations. Bouquets localize at the same fixed distance from the phage nucleus even when it is mispositioned, suggesting an active mechanism for positioning. These results mark the discovery of a pathway for organizing mature viral particles inside bacteria and demonstrate that nucleus-forming jumbo phages, like most eukaryotic viruses, are highly spatially organized during all stages of their lytic cycle.
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Affiliation(s)
- Vorrapon Chaikeeratisak
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
- Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kanika Khanna
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Katrina T Nguyen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - MacKennon E Egan
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eray Enustun
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Emily Armbruster
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jina Lee
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kit Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth Villa
- Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
| | - Joe Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
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4
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Structural and Functional Insight into the Mechanism of Bacillus subtilis 6S-1 RNA Release from RNA Polymerase. Noncoding RNA 2022; 8:ncrna8010020. [PMID: 35202093 PMCID: PMC8876501 DOI: 10.3390/ncrna8010020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 11/29/2022] Open
Abstract
Here we investigated the refolding of Bacillus subtilis 6S-1 RNA and its release from σA-RNA polymerase (σA-RNAP) in vitro using truncated and mutated 6S-1 RNA variants. Truncated 6S-1 RNAs, only consisting of the central bubble (CB) flanked by two short helical arms, can still traverse the mechanistic 6S RNA cycle in vitro despite ~10-fold reduced σA-RNAP affinity. This indicates that the RNA’s extended helical arms including the ‘−35′-like region are not required for basic 6S-1 RNA functionality. The role of the ‘central bubble collapse helix’ (CBCH) in pRNA-induced refolding and release of 6S-1 RNA from σA-RNAP was studied by stabilizing mutations. This also revealed base identities in the 5’-part of the CB (5’-CB), upstream of the pRNA transcription start site (nt 40), that impact ground state binding of 6S-1 RNA to σA-RNAP. Stabilization of the CBCH by the C44/45 double mutation shifted the pRNA length pattern to shorter pRNAs and, combined with a weakened P2 helix, resulted in more effective release from RNAP. We conclude that formation of the CBCH supports pRNA-induced 6S-1 RNA refolding and release. Our mutational analysis also unveiled that formation of a second short hairpin in the 3′-CB is detrimental to 6S-1 RNA release. Furthermore, an LNA mimic of a pRNA as short as 6 nt, when annealed to 6S-1 RNA, retarded the RNA’s gel mobility and interfered with σA-RNAP binding. This effect incrementally increased with pLNA 7- and 8-mers, suggesting that restricted conformational flexibility introduced into the 5’-CB by base pairing with pRNAs prevents 6S-1 RNA from adopting an elongated shape. Accordingly, atomic force microscopy of free 6S-1 RNA versus 6S-1:pLNA 8- and 14-mer complexes revealed that 6S-1:pRNA hybrid structures, on average, adopt a more compact structure than 6S-1 RNA alone. Overall, our findings also illustrate that the wild-type 6S-1 RNA sequence and structure ensures an optimal balance of the different functional aspects involved in the mechanistic cycle of 6S-1 RNA.
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5
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Nazir A, Ali A, Qing H, Tong Y. Emerging Aspects of Jumbo Bacteriophages. Infect Drug Resist 2021; 14:5041-5055. [PMID: 34876823 PMCID: PMC8643167 DOI: 10.2147/idr.s330560] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/30/2021] [Indexed: 01/21/2023] Open
Abstract
The bacteriophages have been explored at a huge scale as a model system for their applications in many biological-related fields. Jumbo phages with a large genome size from 200 to 500 kbp were not previously assigned a great value, and characterized by complex structures coupled with large virions with a wide variety of hosts. The origin of most of the jumbo phages was not well understood; however, many other prominent features have been discovered recently. In the current review, we strive to unearth the most advanced characteristics of jumbo phages, particularly their significance and structural organization that holds immense value to the viral life cycle. The unique characteristics of jumbo phages are the basis of variations in different types of phages concerning their organization at the genomic level, virion structure, evolution, and progeny propagation. The presence of tRNA and additional translation-related genes along with chaperonin genes mark the ability of these phages for being independent of host molecular machinery enabling them to have wide host options. A large number of jumbo phages have been isolated from various sources through advanced standard screening methods. The current review has summarized the available data on jumbo phages and discussed the genome orientation of jumbo phages, translational machinery, diversity and evolution of jumbo phages. In the studies conducted, jumbo phages possessed special additional genes that helps to reduce the dependence of jumbo phages on their hosts. Furthermore, their genomes might have evolved from smaller genome phages.
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Affiliation(s)
- Amina Nazir
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, People’s Republic of China
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, People’s Republic of China
| | - Azam Ali
- Centre for Applied Molecular Biology (CAMB), University of the Punjab, Lahore, Pakistan
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, People’s Republic of China
| | - Yigang Tong
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing, People’s Republic of China
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6
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Ganapathy S, Wiegard JC, Hartmann RK. Rapid preparation of 6S RNA-free B. subtilis σ A-RNA polymerase and σ A. J Microbiol Methods 2021; 190:106324. [PMID: 34506811 DOI: 10.1016/j.mimet.2021.106324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/17/2021] [Accepted: 09/06/2021] [Indexed: 11/25/2022]
Abstract
The regulatory 6S-1 and 6S-2 RNAs of B. subtilis bind to the housekeeping RNA polymerase holoenzyme (σA-RNAP) with submicromolar affinity. We observed copurification of endogenous 6S RNAs from a published B. subtilis strain expressing a His-tagged RNAP. Such 6S RNA contaminations in σA-RNAP preparations reduce the fraction of enzymes that are accessible for binding to DNA promoters. In addition, this leads to background RNA synthesis by σA-RNAP utilizing copurified 6S RNA as template for the synthesis of short abortive transcripts termed product RNAs (pRNAs). To avoid this problem we constructed a B. subtilis strain expressing His-tagged RNAP but carrying deletions of the two 6S RNA genes. The His-tagged, 6S RNA-free σA-RNAP holoenzyme can be prepared with sufficient purity and activity by a single affinity step. We also report expression and separate purification of B. subtilis σA that can be added to the His-tagged RNAP to maximize the amount of holoenzyme and, by inference, in vitro transcription activity.
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Affiliation(s)
- Sweetha Ganapathy
- Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35037 Marburg, Germany
| | - Jana Christin Wiegard
- Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35037 Marburg, Germany
| | - Roland K Hartmann
- Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35037 Marburg, Germany.
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Labarde A, Jakutyte L, Billaudeau C, Fauler B, López-Sanz M, Ponien P, Jacquet E, Mielke T, Ayora S, Carballido-López R, Tavares P. Temporal compartmentalization of viral infection in bacterial cells. Proc Natl Acad Sci U S A 2021; 118:e2018297118. [PMID: 34244425 PMCID: PMC8285916 DOI: 10.1073/pnas.2018297118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Virus infection causes major rearrangements in the subcellular architecture of eukaryotes, but its impact in prokaryotic cells was much less characterized. Here, we show that infection of the bacterium Bacillus subtilis by bacteriophage SPP1 leads to a hijacking of host replication proteins to assemble hybrid viral-bacterial replisomes for SPP1 genome replication. Their biosynthetic activity doubles the cell total DNA content within 15 min. Replisomes operate at several independent locations within a single viral DNA focus positioned asymmetrically in the cell. This large nucleoprotein complex is a self-contained compartment whose boundaries are delimited neither by a membrane nor by a protein cage. Later during infection, SPP1 procapsids localize at the periphery of the viral DNA compartment for genome packaging. The resulting DNA-filled capsids do not remain associated to the DNA transactions compartment. They bind to phage tails to build infectious particles that are stored in warehouse compartments spatially independent from the viral DNA. Free SPP1 structural proteins are recruited to the dynamic phage-induced compartments following an order that recapitulates the viral particle assembly pathway. These findings show that bacteriophages restructure the crowded host cytoplasm to confine at different cellular locations the sequential processes that are essential for their multiplication.
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Affiliation(s)
- Audrey Labarde
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Lina Jakutyte
- Laboratoire de Virologie Moléculaire et Structurale, CNRS Unité Propre de Recherche 3296 and Institut Fédératif de Recherche 115, 91198 Gif-sur-Yvette, France
| | - Cyrille Billaudeau
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Beatrix Fauler
- Microscopy and Cryo-electron Microscopy Service Group, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195, Berlin, Germany
| | - Maria López-Sanz
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain
| | - Prishila Ponien
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198, Gif-sur-Yvette, France
| | - Eric Jacquet
- Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198, Gif-sur-Yvette, France
| | - Thorsten Mielke
- Microscopy and Cryo-electron Microscopy Service Group, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195, Berlin, Germany
| | - Silvia Ayora
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Madrid, Spain
| | - Rut Carballido-López
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Paulo Tavares
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France;
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8
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Chaikeeratisak V, Birkholz EA, Pogliano J. The Phage Nucleus and PhuZ Spindle: Defining Features of the Subcellular Organization and Speciation of Nucleus-Forming Jumbo Phages. Front Microbiol 2021; 12:641317. [PMID: 34326818 PMCID: PMC8314001 DOI: 10.3389/fmicb.2021.641317] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 06/16/2021] [Indexed: 01/21/2023] Open
Abstract
Bacteriophages and their bacterial hosts are ancient organisms that have been co-evolving for billions of years. Some jumbo phages, those with a genome size larger than 200 kilobases, have recently been discovered to establish complex subcellular organization during replication. Here, we review our current understanding of jumbo phages that form a nucleus-like structure, or “Phage Nucleus,” during replication. The phage nucleus is made of a proteinaceous shell that surrounds replicating phage DNA and imparts a unique subcellular organization that is temporally and spatially controlled within bacterial host cells by a phage-encoded tubulin (PhuZ)-based spindle. This subcellular architecture serves as a replication factory for jumbo Pseudomonas phages and provides a selective advantage when these replicate in some host strains. Throughout the lytic cycle, the phage nucleus compartmentalizes proteins according to function and protects the phage genome from host defense mechanisms. Early during infection, the PhuZ spindle positions the newly formed phage nucleus at midcell and, later in the infection cycle, the spindle rotates the nucleus while delivering capsids and distributing them uniformly on the nuclear surface, where they dock for DNA packaging. During the co-infection of two different nucleus-forming jumbo phages in a bacterial cell, the phage nucleus establishes Subcellular Genetic Isolation that limits the potential for viral genetic exchange by physically separating co-infection genomes, and the PhuZ spindle causes Virogenesis Incompatibility, whereby interacting components from two diverging phages negatively affect phage reproduction. Thus, the phage nucleus and PhuZ spindle are defining cell biological structures that serve roles in both the life cycle of nucleus-forming jumbo phages and phage speciation.
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Affiliation(s)
- Vorrapon Chaikeeratisak
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States.,Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Erica A Birkholz
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States
| | - Joe Pogliano
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, United States
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9
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Zhang H, Venkatesan S, Nan B. Myxococcus xanthus as a Model Organism for Peptidoglycan Assembly and Bacterial Morphogenesis. Microorganisms 2021; 9:microorganisms9050916. [PMID: 33923279 PMCID: PMC8144978 DOI: 10.3390/microorganisms9050916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 11/16/2022] Open
Abstract
A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis, because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.
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10
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Trinh JT, Shao Q, Guan J, Zeng L. Emerging heterogeneous compartments by viruses in single bacterial cells. Nat Commun 2020; 11:3813. [PMID: 32732913 PMCID: PMC7393140 DOI: 10.1038/s41467-020-17515-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 07/06/2020] [Indexed: 11/17/2022] Open
Abstract
Spatial organization of biological processes allows for variability in molecular outcomes and coordinated development. Here, we investigate how organization underpins phage lambda development and decision-making by characterizing viral components and processes in subcellular space. We use live-cell and in situ fluorescence imaging at the single-molecule level to examine lambda DNA replication, transcription, virion assembly, and resource recruitment in single-cell infections, uniting key processes of the infection cycle into a coherent model of phage development encompassing space and time. We find that different viral DNAs establish separate subcellular compartments within cells, which sustains heterogeneous viral development in single cells. These individual phage compartments are physically separated by the E. coli nucleoid. Our results provide mechanistic details describing how separate viruses develop heterogeneously to resemble single-cell phenotypes. Here, the authors apply live-cell and in situ fluorescence imaging at the single-molecule level to examine lambda DNA replication in single cells, finding that individual phage DNAs sequester host factors to their own vicinity and confine their replicated DNAs into separate compartments, suggesting that phage decision-making transcripts are spatially organized in separate compartments to allow distinct subcellular decisions to develop.
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Affiliation(s)
- Jimmy T Trinh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA.,Center for Phage Technology, Texas A&M University, College Station, TX, 77843, USA
| | - Qiuyan Shao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA.,Center for Phage Technology, Texas A&M University, College Station, TX, 77843, USA
| | - Jingwen Guan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA.,Center for Phage Technology, Texas A&M University, College Station, TX, 77843, USA.,Molecular and Environmental Plant Science, Texas A&M University, College Station, TX, 77843, USA
| | - Lanying Zeng
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, 77843, USA. .,Center for Phage Technology, Texas A&M University, College Station, TX, 77843, USA. .,Molecular and Environmental Plant Science, Texas A&M University, College Station, TX, 77843, USA.
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11
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Schilling T, Hoppert M, Hertel R. Genomic Analysis of the Recent Viral Isolate vB_BthP-Goe4 Reveals Increased Diversity of φ29-Like Phages. Viruses 2018; 10:E624. [PMID: 30428528 PMCID: PMC6266182 DOI: 10.3390/v10110624] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 11/06/2018] [Accepted: 11/08/2018] [Indexed: 12/14/2022] Open
Abstract
We present the recently isolated virus vB_BthP-Goe4 infecting Bacillus thuringiensis HD1. Morphological investigation via transmission electron microscopy revealed key characteristics of the genus Phi29virus, but with an elongated head resulting in larger virion particles of approximately 50 nm width and 120 nm height. Genome sequencing and analysis resulted in a linear phage chromosome of approximately 26 kb, harbouring 40 protein-encoding genes and a packaging RNA. Sequence comparison confirmed the relation to the Phi29virus genus and genomes of other related strains. A global average nucleotide identity analysis of all identified φ29-like viruses revealed the formation of several new groups previously not observed. The largest group includes Goe4 and may significantly expand the genus Phi29virus (Salasvirus) or the Picovirinae subfamily.
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Affiliation(s)
- Tobias Schilling
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany.
| | - Michael Hoppert
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany.
| | - Robert Hertel
- Department of Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, 37077 Göttingen, Germany.
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12
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Golding I. Infection by bacteriophage lambda: an evolving paradigm for cellular individuality. Curr Opin Microbiol 2018; 43:9-13. [PMID: 29107897 PMCID: PMC5934347 DOI: 10.1016/j.mib.2017.09.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 09/14/2017] [Accepted: 09/25/2017] [Indexed: 12/19/2022]
Abstract
Since the earliest days of molecular biology, bacteriophage lambda has served to illuminate cellular function. Among its many roles, lambda infection is a paradigm for phenotypic heterogeneity among genetically identical cells. Early studies attributed this cellular individuality to random biochemical fluctuations, or 'noise'. More recently, however, attention has turned to the role played by deterministic hidden variables in driving single-cell behavior. Here, I briefly describe how studies in lambda are driving the shift in our understanding of cellular heterogeneity, allowing us to better appreciate the precision at which cells function.
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Affiliation(s)
- Ido Golding
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
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13
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Formation of a Viral Replication Focus in Sulfolobus Cells Infected by the Rudivirus Sulfolobus islandicus Rod-Shaped Virus 2. J Virol 2017; 91:JVI.00486-17. [PMID: 28424282 DOI: 10.1128/jvi.00486-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 04/11/2017] [Indexed: 01/05/2023] Open
Abstract
Viral factories are compartmentalized centers for viral replication and assembly in infected eukaryotic cells. Here, we report the formation of a replication focus by prototypical archaeal Sulfolobus islandicus rod-shaped virus 2 (SIRV2) in the model archaeon Sulfolobus This rod-shaped virus belongs to the viral family Rudiviridae, carrying linear double-stranded DNA (dsDNA) genomes, which are very common in geothermal environments. We demonstrate that SIRV2 DNA synthesis is confined to a focus near the periphery of infected cells. Moreover, viral and cellular replication proteins are recruited to, and concentrated in, the viral replication focus. Furthermore, we show that of the four host DNA polymerases (DNA polymerase I [Dpo1] to Dpo4), only Dpo1 participates in viral DNA synthesis. This constitutes the first report of the formation of a viral replication focus in archaeal cells, suggesting that organization of viral replication in foci is a widespread strategy employed by viruses of the three domains of life.IMPORTANCE The organization of viral replication in foci or viral factories has been mostly described for different eukaryotic viruses and for several bacteriophages. This work constitutes the first report of the formation of a viral replication center by a virus infecting members of the Archaea domain.
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14
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Zepeda Gurrola RC, Fu Y, Rodríguez Luna IC, Benítez Cardoza CG, López López MDJ, López Vidal Y, Gutíerrez GRA, Rodríguez Pérez MA, Guo X. Novel protein interactions with an actin homolog (MreB) of Helicobacter pylori determined by bacterial two-hybrid system. Microbiol Res 2017; 201:39-45. [PMID: 28602400 DOI: 10.1016/j.micres.2017.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/24/2017] [Accepted: 04/22/2017] [Indexed: 02/06/2023]
Abstract
The bacterium Helicobacter pylori infects more than 50% of the world population and causes several gastroduodenal diseases, including gastric cancer. Nevertheless, we still need to explore some protein interactions that may be involved in pathogenesis. MreB, an actin homolog, showed some special characteristics in previous studies, indicating that it could have different functions. Protein functions could be realized via protein-protein interactions. In the present study, the MreB protein from H. pylori 26695 fused with two tags 10×His and GST in tandem was overexpressed and purified from Escherchia coli. The purified recombinant protein was used to perform a pull-down assay with H. pylori 26695 cell lysate. The pulled-down proteins were identified by mass spectrometry (MALDI-TOF), in which the known important proteins related to morphogenesis were absent but several proteins related to pathogenesis process were observed. The bacterial two-hybrid system was further used to evaluate the protein interactions and showed that new interactions of MreB respectively with VacA, UreB, HydB, HylB and AddA were confirmed but the interaction MreB-MreC was not validated. These results indicated that the protein MreB in H. pylori has a distinct interactome, does not participate in cell morphogenesis via MreB-MreC but could be related to pathogenesis.
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Affiliation(s)
| | - Yajuan Fu
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Cd. Reynosa Tamaulipas, Mexico
| | | | | | | | - Yolanda López Vidal
- Facultad de Medicina, División de Investigación, Universidad Nacional Autónoma de Mexico
| | - Germán Rubén Aguilar Gutíerrez
- Centro de Investigación sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
| | - Mario A Rodríguez Pérez
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Cd. Reynosa Tamaulipas, Mexico
| | - Xianwu Guo
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Cd. Reynosa Tamaulipas, Mexico.
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15
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Shiomi D. Polar localization of MreB actin is inhibited by anionic phospholipids in the rod-shaped bacterium Escherichia coli. Curr Genet 2017; 63:845-848. [PMID: 28439631 DOI: 10.1007/s00294-017-0696-5] [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: 04/13/2017] [Revised: 04/20/2017] [Accepted: 04/20/2017] [Indexed: 12/13/2022]
Abstract
Bacterial actin MreB is required for the maintenance of cell polarity. MreB is located underneath the cell membrane and mainly localizes at a central cylindrical part of the cell. In addition, it has recently been found that anionic phospholipids (aPLs: phosphatidylglycerol and cardiolipin) play a crucial role in excluding MreB from the cell poles. Subcellular localization of MreB is positively and negatively regulated by membrane curvature and aPLs, respectively.
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Affiliation(s)
- Daisuke Shiomi
- Department of Life Science, College of Science, Rikkyo University, 3-34-1 Nishi Ikebukuro, Toshima-ku, Tokyo, 171-8501, Japan.
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16
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Abstract
Tailed bacteriophages with genomes larger than 200 kbp are classified as Jumbo phages, and are rarely isolated by conventional methods. These phages are designated “jumbo” owing to their most notable features of a large phage virion and large genome size. However, in addition to these, jumbo phages also exhibit several novel characteristics that have not been observed for phages with smaller genomes, which differentiate jumbo phages in terms of genome organization, virion structure, progeny propagation, and evolution. In this review, we summarize available reports on jumbo phages and discuss the differences between jumbo phages and small-genome phages. We also discuss data suggesting that jumbo phages might have evolved from phages with smaller genomes by acquiring additional functional genes, and that these additional genes reduce the dependence of the jumbo phages on the host bacteria.
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Affiliation(s)
- Yihui Yuan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences Wuhan, PR, China
| | - Meiying Gao
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences Wuhan, PR, China
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17
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Affiliation(s)
- Ido Golding
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030;
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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18
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Abstract
The requirement of DNA polymerases for a 3'-hydroxyl (3'-OH) group to prime DNA synthesis raised the question about how the ends of linear chromosomes could be replicated. Among the strategies that have evolved to handle the end replication problem, a group of linear phages and eukaryotic and archaeal viruses, among others, make use of a protein (terminal protein, TP) that primes DNA synthesis from the end of their genomes. The replicative DNA polymerase recognizes the OH group of a specific residue in the TP to initiate replication that is guided by an internal 3' nucleotide of the template strand. By a sliding-back mechanism or variants of it the terminal nucleotide(s) is(are) recovered and the TP becomes covalently attached to the genome ends. Bacillus subtilis phage ϕ29 is the organism in which such a mechanism has been studied more extensively, having allowed to lay the foundations of the so-called protein-primed replication mechanism. Here we focus on the main biochemical and structural features of the two main proteins responsible for the protein-primed initiation step: the DNA polymerase and the TP. Thus, we will discuss the structural determinants of the DNA polymerase responsible for its ability to use sequentially a TP and a DNA as primers, as well as for its inherent capacity to couple high processive synthesis to strand displacement. On the other hand, we will review how TP primes initiation followed by a transition step for further DNA-primed replication by the same polymerase molecule. Finally, we will review how replication is compartmentalized in vivo.
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Affiliation(s)
- M Salas
- Instituto de Biología Molecular "Eladio Viñuela" (CSIC), Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.
| | - M de Vega
- Instituto de Biología Molecular "Eladio Viñuela" (CSIC), Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain.
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19
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Juan PA, Attaiech L, Charpentier X. Natural transformation occurs independently of the essential actin-like MreB cytoskeleton in Legionella pneumophila. Sci Rep 2015; 5:16033. [PMID: 26526572 PMCID: PMC4630621 DOI: 10.1038/srep16033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 10/08/2015] [Indexed: 11/10/2022] Open
Abstract
Natural transformation is the process by which bacteria can actively take up and integrate exogenous DNA thereby providing a source of genetic diversity. Under specific growth conditions the coordinated expression of several genes – a situation referred to as “competence” – allows bacteria to assemble a highly processive and dedicated system that can import high molecular weight DNA. Within the cell these large imported DNA molecules are protected from degradation and brought to the chromosome for recombination. Here, we report elevated expression of mreB during competence in the Gram-negative pathogen Legionella pneumophila. Interestingly a similar observation had previously been reported in the distantly-related Gram-positive organism Bacillus subtilis. MreB is often viewed as the bacterial actin homolog contributing to bacterial morphogenesis by coordinating peptidoglycan-synthesising complexes. In addition MreB is increasingly found to be involved in a growing number of processes including chromosome segregation and motor-driven motility. Using genetic and pharmacological approaches, we examined the possible role of MreB during natural transformation in L. pneumophila. Our data show that natural transformation does not require MreB dynamics and exclude a direct role of MreB filaments in the transport of foreign DNA and its recombination in the chromosome.
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Affiliation(s)
- Pierre-Alexandre Juan
- CNRS UMR5240 MAP, Villeurbanne, France.,Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Laetitia Attaiech
- CNRS UMR5240 MAP, Villeurbanne, France.,Université Claude Bernard Lyon 1, Villeurbanne, France
| | - Xavier Charpentier
- CNRS UMR5240 MAP, Villeurbanne, France.,Université Claude Bernard Lyon 1, Villeurbanne, France
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20
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Donovan C, Heyer A, Pfeifer E, Polen T, Wittmann A, Krämer R, Frunzke J, Bramkamp M. A prophage-encoded actin-like protein required for efficient viral DNA replication in bacteria. Nucleic Acids Res 2015; 43:5002-16. [PMID: 25916847 PMCID: PMC4446434 DOI: 10.1093/nar/gkv374] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/09/2015] [Indexed: 12/31/2022] Open
Abstract
In host cells, viral replication is localized at specific subcellular sites. Viruses that infect eukaryotic and prokaryotic cells often use host-derived cytoskeletal structures, such as the actin skeleton, for intracellular positioning. Here, we describe that a prophage, CGP3, integrated into the genome of Corynebacterium glutamicum encodes an actin-like protein, AlpC. Biochemical characterization confirms that AlpC is a bona fide actin-like protein and cell biological analysis shows that AlpC forms filamentous structures upon prophage induction. The co-transcribed adaptor protein, AlpA, binds to a consensus sequence in the upstream promoter region of the alpAC operon and also interacts with AlpC, thus connecting circular phage DNA to the actin-like filaments. Transcriptome analysis revealed that alpA and alpC are among the early induced genes upon excision of the CGP3 prophage. Furthermore, qPCR analysis of mutant strains revealed that both AlpA and AlpC are required for efficient phage replication. Altogether, these data emphasize that AlpAC are crucial for the spatio-temporal organization of efficient viral replication. This is remarkably similar to actin-assisted membrane localization of eukaryotic viruses that use the actin cytoskeleton to concentrate virus particles at the egress sites and provides a link of evolutionary conserved interactions between intracellular virus transport and actin.
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Affiliation(s)
- Catriona Donovan
- Department of Biology I, Ludwig-Maximilians-University Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Antonia Heyer
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Eugen Pfeifer
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Tino Polen
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Anja Wittmann
- Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Reinhard Krämer
- Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Julia Frunzke
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Marc Bramkamp
- Department of Biology I, Ludwig-Maximilians-University Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
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21
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Revealing bacterial targets of growth inhibitors encoded by bacteriophage T7. Proc Natl Acad Sci U S A 2014; 111:18715-20. [PMID: 25512533 DOI: 10.1073/pnas.1413271112] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Today's arsenal of antibiotics is ineffective against some emerging strains of antibiotic-resistant pathogens. Novel inhibitors of bacterial growth therefore need to be found. The target of such bacterial-growth inhibitors must be identified, and one way to achieve this is by locating mutations that suppress their inhibitory effect. Here, we identified five growth inhibitors encoded by T7 bacteriophage. High-throughput sequencing of genomic DNA of resistant bacterial mutants evolving against three of these inhibitors revealed unique mutations in three specific genes. We found that a nonessential host gene, ppiB, is required for growth inhibition by one bacteriophage inhibitor and another nonessential gene, pcnB, is required for growth inhibition by a different inhibitor. Notably, we found a previously unidentified growth inhibitor, gene product (Gp) 0.6, that interacts with the essential cytoskeleton protein MreB and inhibits its function. We further identified mutations in two distinct regions in the mreB gene that overcome this inhibition. Bacterial two-hybrid assay and accumulation of Gp0.6 only in MreB-expressing bacteria confirmed interaction of MreB and Gp0.6. Expression of Gp0.6 resulted in lemon-shaped bacteria followed by cell lysis, as previously reported for MreB inhibitors. The described approach may be extended for the identification of new growth inhibitors and their targets across bacterial species and in higher organisms.
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22
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Jin M, Chen Y, Xu C, Zhang X. The effect of inhibition of host MreB on the infection of thermophilic phage GVE2 in high temperature environment. Sci Rep 2014; 4:4823. [PMID: 24769758 PMCID: PMC4001104 DOI: 10.1038/srep04823] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 04/03/2014] [Indexed: 11/09/2022] Open
Abstract
In eukaryotes, the manipulation of the host actin cytoskeleton is a necessary strategy for viral pathogens to invade host cells. Increasing evidence indicates that the actin homolog MreB of bacteria plays key roles in cell shape formation, cell polarity, cell wall biosynthesis, and chromosome segregation. However, the role of bacterial MreB in the bacteriophage infection is not extensively investigated. To address this issue, in this study, the MreB of thermophilic Geobacillus sp. E263 from a deep-sea hydrothermal field was characterized by inhibiting the MreB polymerization and subsequently evaluating the bacteriophage GVE2 infection. The results showed that the host MreB played important roles in the bacteriophage infection at high temperature. After the host cells were treated with small molecule drug A22 or MP265, the specific inhibitors of MreB polymerization, the adsorption of GVE2 and the replication of GVE2 genome were significantly repressed. The confocal microscopy data revealed that MreB facilitated the GVE2 infection by inducing the polar distribution of virions during the phage infection. Our study contributed novel information to understand the molecular events of the host in response to bacteriophage challenge and extended our knowledge about the host-virus interaction in deep-sea vent ecosystems.
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Affiliation(s)
- Min Jin
- 1] Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, The People's Republic of China [2]
| | - Yanjiang Chen
- 1] Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, The People's Republic of China [2]
| | - Chenxi Xu
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, The People's Republic of China
| | - Xiaobo Zhang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou 310058, The People's Republic of China
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23
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Endesfelder U, Finan K, Holden SJ, Cook PR, Kapanidis AN, Heilemann M. Multiscale spatial organization of RNA polymerase in Escherichia coli. Biophys J 2014; 105:172-81. [PMID: 23823236 DOI: 10.1016/j.bpj.2013.05.048] [Citation(s) in RCA: 131] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 05/10/2013] [Accepted: 05/29/2013] [Indexed: 12/26/2022] Open
Abstract
Nucleic acid synthesis is spatially organized in many organisms. In bacteria, however, the spatial distribution of transcription remains obscure, owing largely to the diffraction limit of conventional light microscopy (200-300 nm). Here, we use photoactivated localization microscopy to localize individual molecules of RNA polymerase (RNAP) in Escherichia coli with a spatial resolution of ∼40 nm. In cells growing rapidly in nutrient-rich media, we find that RNAP is organized in 2-8 bands. The band number scaled directly with cell size (and so with the chromosome number), and bands often contained clusters of >70 tightly packed RNAPs (possibly engaged on one long ribosomal RNA operon of 6000 bp) and clusters of such clusters (perhaps reflecting a structure like the eukaryotic nucleolus where many different ribosomal RNA operons are transcribed). In nutrient-poor media, RNAPs were located in only 1-2 bands; within these bands, a disproportionate number of RNAPs were found in clusters containing ∼20-50 RNAPs. Apart from their importance for bacterial transcription, our studies pave the way for molecular-level analysis of several cellular processes at the nanometer scale.
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Affiliation(s)
- Ulrike Endesfelder
- Institute of Physical and Theoretical Chemistry, Johann Wolfgang Goethe-University, Frankfurt, Germany
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24
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Karttunen J, Mäntynen S, Ihalainen TO, Lehtivuori H, Tkachenko NV, Vihinen-Ranta M, Ihalainen JA, Bamford JKH, Oksanen HM. Subcellular localization of bacteriophage PRD1 proteins in Escherichia coli. Virus Res 2014; 179:44-52. [PMID: 24291253 DOI: 10.1016/j.virusres.2013.11.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/19/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022]
Abstract
Bacteria possess an intricate internal organization resembling that of the eukaryotes. The complexity is especially prominent at the bacterial cell poles, which are also known to be the preferable sites for some bacteriophages to infect. Bacteriophage PRD1 is a well-known model serving as an ideal system to study structures and functions of icosahedral internal membrane-containing viruses. Our aim was to analyze the localization and interactions of individual PRD1 proteins in its native host Escherichia coli. This was accomplished by constructing a vector library for production of fluorescent fusion proteins. Analysis of solubility and multimericity of the fusion proteins, as well as their localization in living cells by confocal microscopy, indicated that multimeric PRD1 proteins were prone to localize in the cell poles. Furthermore, PRD1 spike complex proteins P5 and P31, as fusion proteins, were shown to be functional in the virion assembly. In addition, they were shown to co-localize in the specific polar area of the cells, which might have a role in the multimerization and formation of viral protein complexes.
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Affiliation(s)
- Jenni Karttunen
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Sari Mäntynen
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Teemu O Ihalainen
- Nanoscience Center, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Heli Lehtivuori
- Nanoscience Center, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Nikolai V Tkachenko
- Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, 33101 Tampere, Finland
| | - Maija Vihinen-Ranta
- Nanoscience Center, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Janne A Ihalainen
- Nanoscience Center, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Jaana K H Bamford
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, P.O. Box 35, 40014 University of Jyväskylä, Finland
| | - Hanna M Oksanen
- Institute of Biotechnology and Department of Biosciences, P.O. Box 56, 00014 University of Helsinki, Finland.
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25
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Rueff AS, Chastanet A, Domínguez-Escobar J, Yao Z, Yates J, Prejean MV, Delumeau O, Noirot P, Wedlich-Söldner R, Filipe SR, Carballido-López R. An early cytoplasmic step of peptidoglycan synthesis is associated to MreB in Bacillus subtilis. Mol Microbiol 2013; 91:348-62. [PMID: 24261876 DOI: 10.1111/mmi.12467] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2013] [Indexed: 12/23/2022]
Abstract
MreB proteins play a major role during morphogenesis of rod-shaped bacteria by organizing biosynthesis of the peptidoglycan cell wall. However, the mechanisms underlying this process are not well understood. In Bacillus subtilis, membrane-associated MreB polymers have been shown to be associated to elongation-specific complexes containing transmembrane morphogenetic factors and extracellular cell wall assembly proteins. We have now found that an early intracellular step of cell wall synthesis is also associated to MreB. We show that the previously uncharacterized protein YkuR (renamed DapI) is required for synthesis of meso-diaminopimelate (m-DAP), an essential constituent of the peptidoglycan precursor, and that it physically interacts with MreB. Highly inclined laminated optical sheet microscopy revealed that YkuR forms uniformly distributed foci that exhibit fast motion in the cytoplasm, and are not detected in cells lacking MreB. We propose a model in which soluble MreB organizes intracellular steps of peptidoglycan synthesis in the cytoplasm to feed the membrane-associated cell wall synthesizing machineries.
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Affiliation(s)
- Anne-Stéphanie Rueff
- INRA, UMR1319 Micalis, F-78352, Jouy-en-Josas, France; AgroParisTech, UMR1319 Micalis, F-78352, Jouy-en-Josas, France
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26
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Holguera I, Redrejo-Rodríguez M, Salas M, Muñoz-Espín D. New insights in the ϕ29 terminal protein DNA-binding and host nucleoid localization functions. Mol Microbiol 2013; 91:232-41. [PMID: 24205926 DOI: 10.1111/mmi.12456] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2013] [Indexed: 11/30/2022]
Abstract
Protein-primed DNA replication constitutes a strategy to initiate viral DNA synthesis in a variety of prokaryotic and eukaryotic organisms. Although the main function of viral terminal proteins (TPs) is to provide a free hydroxyl group to start initiation of DNA replication, there are compelling evidences that TPs can also play other biological roles. In the case of Bacillus subtilis bacteriophage ϕ29, the N-terminal domain of the TP organizes viral DNA replication at the bacterial nucleoid being essential for an efficient phage DNA replication, and it contains a nuclear localization signal (NLS) that is functional in eukaryotes. Here we provide information about the structural properties of the ϕ29 TP N-terminal domain, which possesses sequence-independent DNA-binding capacity, and dissect the amino acid residues important for its biological function. By mutating all the basic residues of the TP N-terminal domain we identify the amino acids responsible for its interaction with the B. subtilis genome, establishing a correlation between the capacity of DNA-binding and nucleoid localization of the protein. Significantly, these residues are important to recruit the DNA polymerase at the bacterial nucleoid and, subsequently, for an efficient phage DNA replication.
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Affiliation(s)
- Isabel Holguera
- Instituto de Biología Molecular 'Eladio Viñuela' (Consejo Superior de Investigaciones Científicas), Centro de Biología Molecular 'Severo Ochoa' (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049, Madrid, Spain
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27
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Tone T, Takeuchi A, Makino O. Functional linkages between replication proteins of genes 1, 3 and 5 of Bacillus subtilis phage φ29. Genes Genet Syst 2013; 87:347-56. [PMID: 23558641 DOI: 10.1266/ggs.87.347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Gene 1 product (gp1) of Bacillus subtilis phage φ29 has been shown to be involved in viral DNA replication in vivo, but the essential role is still unknown. As part of an ongoing effort to understand the role of gp1 in viral DNA replication, we investigated genetic interaction between gene 1 and other viral genes. Because φ29 mutants which do not produce functional gp1 show temperature-sensitive growth, we isolated temperature-resistant phages from the φ29 gene 1 mutants, and eventually, obtained nine extragenic suppressors. These suppressor mutations were located in two essential genes for φ29 DNA replication in vivo: gene 3 encoding terminal/primer protein (gp3) or gene 5 encoding viral single-stranded DNA binding protein (gp5). Most of these mutations resulted in single amino acid substitutions in the products. By trans-complementation assay, we confirmed that the absence of gp1 at non-permissive temperature can be compensated by the suppressors which have the single amino acid substitution in either gp5 or gp3. These results indicate that gp1 has functional relationship to gp5 and gp3. From the positions of amino acid substitutions in gp3, we propose its new regulatory subdomain at which other molecules including gp1 would interact with and regulate functions of gp3.
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Affiliation(s)
- Takahiro Tone
- Laboratory of genetics, Department of Material and Life Science, Faculty of Science and Technology, Sophia University, Tokyo, Japan
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28
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Phage 29 phi protein p1 promotes replication by associating with the FtsZ ring of the divisome in Bacillus subtilis. Proc Natl Acad Sci U S A 2013; 110:12313-8. [PMID: 23836667 DOI: 10.1073/pnas.1311524110] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During evolution, viruses have optimized the interaction with host factors to increase the efficiency of fundamental processes such as DNA replication. Bacteriophage 29 protein p1 is a membrane-associated protein that forms large protofilament sheets that resemble eukaryotic tubulin and bacterial filamenting temperature-sensitive mutant Z protein (FtsZ) polymers. In the absence of protein p1, phage 29 DNA replication is impaired. Here we show that a functional fusion of protein p1 to YFP localizes at the medial region of Bacillus subtilis cells independently of other phage-encoded proteins. We also show that 29 protein p1 colocalizes with the B. subtilis cell division protein FtsZ and provide evidence that FtsZ and protein p1 are associated. Importantly, the midcell localization of YFP-p1 was disrupted in a strain that does not express FtsZ, and the fluorescent signal was distributed all over the cell. Depletion of penicillin-binding protein 2B (PBP2B) in B. subtilis cells did not affect the subcellular localization of YFP-p1, indicating that its distribution does not depend on septal wall synthesis. Interestingly, when 29 protein p1 was expressed, B. subtilis cells were about 1.5-fold longer than control cells, and the accumulation of 29 DNA was higher in mutant B. subtilis cells with increased length. We discuss the biological role of p1 and FtsZ in the 29 growth cycle.
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29
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Abstract
During the course of evolution, viruses have learned to take advantage of the natural resources of their hosts for their own benefit. Due to their small dimension and limited size of genomes, bacteriophages have optimized the exploitation of bacterial host factors to increase the efficiency of DNA replication and hence to produce vast progeny. The Bacillus subtilis phage φ29 genome consists of a linear double-stranded DNA molecule that is duplicated by means of a protein-primed mode of DNA replication. Its genome has been shown to be topologically constrained at the size of the bacterial nucleoid and, as to avoid generation of positive supercoiling ahead of the replication forks, the bacterial DNA gyrase is used by the phage. In addition, the B. subtilis actin-like MreB cytoskeleton plays a crucial role in the organization of φ29 DNA replication machinery in peripheral helix-like structures. Thus, in the absence of an intact MreB cytoskeleton, φ29 DNA replication is severely impaired. Importantly, MreB interacts directly with the phage membrane protein p16.7, responsible for attaching φ29 DNA at the cell membrane. Moreover, the φ29-encoded protein p56 inhibits host uracil-DNA glycosylase activity and has been proposed to be a defense mechanism developed by the phage to prevent the action of the base excision repair pathway if uracil residues arise in replicative intermediates. All of them constitute incoming examples on how viruses have profited from the cellular machinery of their hosts.
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Johnson MA, Sharma M, Mok MTS, Henderson BR. Stimulation of in vivo nuclear transport dynamics of actin and its co-factors IQGAP1 and Rac1 in response to DNA replication stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2334-47. [PMID: 23770048 DOI: 10.1016/j.bbamcr.2013.06.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 05/31/2013] [Accepted: 06/04/2013] [Indexed: 10/26/2022]
Abstract
Actin, a constituent of the cytoskeleton, is now recognized to function in the nucleus in gene transcription, chromatin remodeling and DNA replication/repair. Actin shuttles in and out of the nucleus through the action of transport receptors importin-9 and exportin-6. Here we have addressed the impact of cell cycle progression and DNA replication stress on actin nuclear localization, through study of actin dynamics in living cells. First, we showed that thymidine-induced G1/S phase cell cycle arrest increased the nuclear levels of actin and of two factors that stimulate actin polymerization: IQGAP1 and Rac1 GTPase. When cells were exposed to hydroxyurea to induce DNA replication stress, the nuclear localization of actin and its regulators was further enhanced. We employed live cell photobleaching assays and discovered that in response to DNA replication stress, GFP-actin nuclear import and export rates increased by up to 250%. The rate of import was twice as fast as export, accounting for actin nuclear accumulation. The faster shuttling dynamics correlated with reduced cellular retention of actin, and our data implicate actin polymerization in the stress-dependent uptake of nuclear actin. Furthermore, DNA replication stress induced a nuclear shift in IQGAP1 and Rac1 with enhanced import dynamics. Proximity ligation assays revealed that IQGAP1 associates in the nucleus with actin and Rac1, and formation of these complexes increased after hydroxyurea treatment. We propose that the replication stress checkpoint triggers co-ordinated nuclear entry and trafficking of actin, and of factors that regulate actin polymerization.
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Affiliation(s)
- Michael A Johnson
- Westmead Institute for Cancer Research, The University of Sydney, Westmead, Australia
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31
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Abstract
This article is a survey of my scientific work over 52 years. During my postdoctoral stay in Severo Ochoa's laboratory, I determined the direction of reading of the genetic message, and I discovered two proteins that I showed to be involved in the initiation of protein synthesis. The work I have done in Spain with bacteriophage ϕ29 for 45 years has been very rewarding. I can say that I was lucky because I did not expect that ϕ29 would give so many interesting results, but I worked hard, with a lot of dedication and enthusiasm, and I was there when the luck arrived. I would like to emphasize our work on the control of ϕ29 DNA transcription and, in particular, the finding for the first time of a protein covalently linked to the 5'-ends of ϕ29 DNA that we later showed to be the primer for the initiation of phage DNA replication. Very relevant was the discovery of the ϕ29 DNA polymerase, with its properties of extremely high processivity and strand displacement capacity, together with its high fidelity. The ϕ29 DNA polymerase has become an ideal enzyme for DNA amplification, both rolling-circle and whole-genome linear amplification. I am also very proud of the many brilliant students and collaborators with whom I have worked over the years and who have become excellent scientists. This Reflections article is not intended to be the end of my scientific career. I expect to work for many years to come.
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Affiliation(s)
- Margarita Salas
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
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32
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Kraemer JA, Erb ML, Waddling CA, Montabana EA, Zehr EA, Wang H, Nguyen K, Pham DSL, Agard DA, Pogliano J. A phage tubulin assembles dynamic filaments by an atypical mechanism to center viral DNA within the host cell. Cell 2012; 149:1488-99. [PMID: 22726436 DOI: 10.1016/j.cell.2012.04.034] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/27/2012] [Accepted: 04/13/2012] [Indexed: 01/24/2023]
Abstract
Tubulins are essential for the reproduction of many eukaryotic viruses, but historically, bacteriophage were assumed not to require a cytoskeleton. Here, we identify a tubulin-like protein, PhuZ, from bacteriophage 201φ2-1 and show that it forms filaments in vivo and in vitro. The PhuZ structure has a conserved tubulin fold, with an unusual, extended C terminus that we demonstrate to be critical for polymerization in vitro and in vivo. Longitudinal packing in the crystal lattice mimics packing observed by EM of in-vitro-formed filaments, indicating how interactions between the C terminus and the following monomer drive polymerization. PhuZ forms a filamentous array that is required for positioning phage DNA within the bacterial cell. Correct positioning to the cell center and optimal phage reproduction only occur when the PhuZ filament is dynamic. Thus, we show that PhuZ assembles a spindle-like array that functions analogously to the microtubule-based spindles of eukaryotes.
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Affiliation(s)
- James A Kraemer
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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33
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Disclosing the in vivo organization of a viral histone-like protein in Bacillus subtilis mediated by its capacity to recognize the viral genome. Proc Natl Acad Sci U S A 2012; 109:5723-8. [PMID: 22451942 DOI: 10.1073/pnas.1203824109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Organization of replicating prokaryotic genomes requires architectural elements that, similarly to eukaryotic systems, induce topological changes such as DNA supercoiling. Bacteriophage 29 protein p6 has been described as a histone-like protein that compacts the viral genome by forming a nucleoprotein complex and plays a key role in the initiation of protein-primed DNA replication. In this work, we analyze the subcellular localization of protein p6 by immunofluorescence microscopy and show that, at early infection stages, it localizes in a peripheral helix-like configuration. Later, at middle infection stages, protein p6 is recruited to the bacterial nucleoid. This migrating process is shown to depend on the synthesis of components of the 29 DNA replication machinery (i.e., terminal protein and DNA polymerase) needed for the replication of viral DNA, which is required to recruit the bulk of protein p6. Importantly, the double-stranded DNA-binding capacity of protein p6 is essential for its relocalization at the nucleoid. Altogether, the results disclose the in vivo organization of a viral histone-like protein in bacteria.
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34
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Häuser R, Blasche S, Dokland T, Haggård-Ljungquist E, von Brunn A, Salas M, Casjens S, Molineux I, Uetz P. Bacteriophage protein-protein interactions. Adv Virus Res 2012; 83:219-98. [PMID: 22748812 PMCID: PMC3461333 DOI: 10.1016/b978-0-12-394438-2.00006-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Bacteriophages T7, λ, P22, and P2/P4 (from Escherichia coli), as well as ϕ29 (from Bacillus subtilis), are among the best-studied bacterial viruses. This chapter summarizes published protein interaction data of intraviral protein interactions, as well as known phage-host protein interactions of these phages retrieved from the literature. We also review the published results of comprehensive protein interaction analyses of Pneumococcus phages Dp-1 and Cp-1, as well as coliphages λ and T7. For example, the ≈55 proteins encoded by the T7 genome are connected by ≈43 interactions with another ≈15 between the phage and its host. The chapter compiles published interactions for the well-studied phages λ (33 intra-phage/22 phage-host), P22 (38/9), P2/P4 (14/3), and ϕ29 (20/2). We discuss whether different interaction patterns reflect different phage lifestyles or whether they may be artifacts of sampling. Phages that infect the same host can interact with different host target proteins, as exemplified by E. coli phage λ and T7. Despite decades of intensive investigation, only a fraction of these phage interactomes are known. Technical limitations and a lack of depth in many studies explain the gaps in our knowledge. Strategies to complete current interactome maps are described. Although limited space precludes detailed overviews of phage molecular biology, this compilation will allow future studies to put interaction data into the context of phage biology.
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Affiliation(s)
- Roman Häuser
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Sonja Blasche
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
| | - Terje Dokland
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Albrecht von Brunn
- Max-von-Pettenkofer-Institut, Lehrstuhl Virologie, Ludwig-Maximilians-Universität, München, Germany
| | - Margarita Salas
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Cantoblanco, Madrid, Spain
| | - Sherwood Casjens
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah
| | - Ian Molineux
- Molecular Genetics and Microbiology, Institute for Cell and Molecular Biology, University of Texas–Austin, Austin, Texas, USA
| | - Peter Uetz
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, Virginia, USA
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35
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Nucleocytoplasmic shuttling of cytoskeletal proteins: molecular mechanism and biological significance. Int J Cell Biol 2011; 2012:494902. [PMID: 22229032 PMCID: PMC3249633 DOI: 10.1155/2012/494902] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/03/2011] [Accepted: 10/06/2011] [Indexed: 01/04/2023] Open
Abstract
Various nuclear functional complexes contain cytoskeletal proteins as regulatory subunits; for example, nuclear actin participates in transcriptional complexes, and actin-related proteins are integral to chromatin remodeling complexes. Nuclear complexes such as these are involved in both basal and adaptive nuclear functions. In addition to nuclear import via classical nuclear transport pathways or passive diffusion, some large cytoskeletal proteins spontaneously migrate into the nucleus in a karyopherin-independent manner. The balance of nucleocytoplasmic distribution of such proteins can be altered by several factors, such as import versus export, or capture and release by complexes. The resulting accumulation or depletion of the nuclear populations thereby enhances or attenuates their nuclear functions. We propose that such molecular dynamics constitute a form of cytoskeleton-modulated regulation of nuclear functions which is mediated by the translocation of cytoskeletal components in and out of the nucleus.
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36
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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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37
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Bacteriophage infection in rod-shaped gram-positive bacteria: evidence for a preferential polar route for phage SPP1 entry in Bacillus subtilis. J Bacteriol 2011; 193:4893-903. [PMID: 21705600 DOI: 10.1128/jb.05104-11] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Entry into the host bacterial cell is one of the least understood steps in the life cycle of bacteriophages. The different envelopes of Gram-negative and Gram-positive bacteria, with a fluid outer membrane and exposing a thick peptidoglycan wall to the environment respectively, impose distinct challenges for bacteriophage binding and (re)distribution on the bacterial surface. Here, infection of the Gram-positive rod-shaped bacterium Bacillus subtilis by bacteriophage SPP1 was monitored in space and time. We found that SPP1 reversible adsorption occurs preferentially at the cell poles. This initial binding facilitates irreversible adsorption to the SPP1 phage receptor protein YueB, which is encoded by a putative type VII secretion system gene cluster. YueB was found to concentrate at the cell poles and to display a punctate peripheral distribution along the sidewalls of B. subtilis cells. The kinetics of SPP1 DNA entry and replication were visualized during infection. Most of the infecting phages DNA entered and initiated replication near the cell poles. Altogether, our results reveal that the preferentially polar topology of SPP1 receptors on the surface of the host cell determines the site of phage DNA entry and subsequent replication, which occurs in discrete foci.
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38
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Abstract
Bacteria, like eukaryotes, employ cytoskeletal elements to perform many functions, including cell morphogenesis, cell division, DNA partitioning, and cell motility. They not only possess counterparts of eukaryotic actin, tubulin, and intermediate filament proteins, but they also have cytoskeletal elements of their own. Unlike the rigid sequence and structural conservation often observed for eukaryotic cytoskeletal proteins, the bacterial counterparts can display considerable diversity in sequence and function across species. Their wide range of function highlights the flexibility of core cytoskeletal protein motifs, such that one type of cytoskeletal element can perform various functions, and one function can be performed by different types of cytoskeletal elements.
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Affiliation(s)
- Matthew T Cabeen
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut 06520, USA
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39
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Skarp KP, Vartiainen MK. Actin on DNA-an ancient and dynamic relationship. Cytoskeleton (Hoboken) 2010; 67:487-95. [PMID: 20593452 DOI: 10.1002/cm.20464] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the cytoplasm of eukaryotic cells the coordinated assembly of actin filaments drives essential cell biological processes, such as cell migration. The discovery of prokaryotic actin homologues, as well as the appreciation of the existence of nuclear actin, have expanded the scope by which the actin family is utilized in different cell types. In bacteria, actin has been implicated in DNA movement tasks, while the connection with the RNA polymerase machinery appears to exist in both prokaryotes and eukaryotes. Within the nucleus, actin has further been shown to play a role in chromatin remodeling and RNA processing, possibly acting to link these to transcription, thereby facilitating the gene expression process. The molecular mechanism by which actin exerts these newly discovered functions is still unclear, because while polymer formation seems to be required in bacteria, these species lack conventional actin-binding proteins to regulate the process. Furthermore, although the nucleus contains a plethora of actin-regulating factors, the polymerization status of actin within this compartment still remains unclear. General theme, however, seems to be actin's ability to interact with numerous binding partners. A common feature to the novel modes of actin utilization is the connection between actin and DNA, and here we aim to review the recent literature to explore how this connection is exploited in different contexts.
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Affiliation(s)
- Kari-Pekka Skarp
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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40
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Chromatography-bioluminescence coupling reveals surprising bioactivity of inthomycin A. Anal Bioanal Chem 2010; 398:2081-8. [PMID: 20842351 DOI: 10.1007/s00216-010-4086-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 07/30/2010] [Accepted: 08/02/2010] [Indexed: 10/19/2022]
Abstract
By employing a novel technique for the direct coupling of a bacterial bioassay with chromatography, we discovered a gyrA promotor active compound in myxobacterial extracts and elucidated the structure directly without any isolation step. As a result, we identified inthomycin A as the bioactive substance. Our method is based on a whole-cell bioluminescent reporter gene assay coupled with thin-layer chromatography for primary hit detection and with liquid chromatography (LC)/mass spectrometry or LC/NMR for dereplication and structure elucidation. Previously, inthomycin A has been isolated from Streptomycetes and was associated with the inhibition of cellulose biosynthesis and herbicidal activity. Thus, our findings support the basic principle that completely different microbial phyla are able to synthesize the same natural product. Moreover, our results indicate that inthomycin A affects bacterial DNA supercoiling, which reveals an unexpected bioactivity for this compound. These results can possibly promote further investigation of the biosynthesis as well as the biological activity of inthomycins and related natural products.
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41
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Viral terminal protein directs early organization of phage DNA replication at the bacterial nucleoid. Proc Natl Acad Sci U S A 2010; 107:16548-53. [PMID: 20823229 DOI: 10.1073/pnas.1010530107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mechanism leading to protein-primed DNA replication has been studied extensively in vitro. However, little is known about the in vivo organization of the proteins involved in this fundamental process. Here we show that the terminal proteins (TPs) of phages ϕ29 and PRD1, infecting the distantly related bacteria Bacillus subtilis and Escherichia coli, respectively, associate with the host bacterial nucleoid independently of other viral-encoded proteins. Analyses of phage ϕ29 revealed that the TP N-terminal domain (residues 1-73) possesses sequence-independent DNA-binding capacity and is responsible for its nucleoid association. Importantly, we show that in the absence of the TP N-terminal domain the efficiency of ϕ29 DNA replication is severely affected. Moreover, the TP recruits the phage DNA polymerase to the bacterial nucleoid, and both proteins later are redistributed to enlarged helix-like structures in an MreB cytoskeleton-dependent way. These data disclose a key function for the TP in vivo: organizing the early viral DNA replication machinery at the cell nucleoid.
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42
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Shaevitz JW, Gitai Z. The structure and function of bacterial actin homologs. Cold Spring Harb Perspect Biol 2010; 2:a000364. [PMID: 20630996 DOI: 10.1101/cshperspect.a000364] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
During the past decade, the appreciation and understanding of how bacterial cells can be organized in both space and time have been revolutionized by the identification and characterization of multiple bacterial homologs of the eukaryotic actin cytoskeleton. Some of these bacterial actins, such as the plasmid-borne ParM protein, have highly specialized functions, whereas other bacterial actins, such as the chromosomally encoded MreB protein, have been implicated in a wide array of cellular activities. In this review we cover our current understanding of the structure, assembly, function, and regulation of bacterial actins. We focus on ParM as a well-understood reductionist model and on MreB as a central organizer of multiple aspects of bacterial cell biology. We also discuss the outstanding puzzles in the field and possible directions where this fast-developing area may progress in the future.
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Affiliation(s)
- Joshua W Shaevitz
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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43
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Decision making at a subcellular level determines the outcome of bacteriophage infection. Cell 2010; 141:682-91. [PMID: 20478257 DOI: 10.1016/j.cell.2010.03.034] [Citation(s) in RCA: 169] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 01/25/2010] [Accepted: 02/22/2010] [Indexed: 01/28/2023]
Abstract
When the process of cell-fate determination is examined at single-cell resolution, it is often observed that individual cells undergo different fates even when subject to identical conditions. This "noisy" phenotype is usually attributed to the inherent stochasticity of chemical reactions in the cell. Here we demonstrate how the observed single-cell heterogeneity can be explained by a cascade of decisions occurring at the subcellular level. We follow the postinfection decision in bacteriophage lambda at single-virus resolution, and show that a choice between lysis and lysogeny is first made at the level of the individual virus. The decisions by all viruses infecting a single cell are then integrated in a precise (noise-free) way, such that only a unanimous vote by all viruses leads to the establishment of lysogeny. By detecting and integrating over the subcellular "hidden variables," we are able to predict the level of noise measured at the single-cell level.
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44
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Near-isotropic 3D optical nanoscopy with photon-limited chromophores. Proc Natl Acad Sci U S A 2010; 107:10068-73. [PMID: 20472826 DOI: 10.1073/pnas.1004899107] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Imaging approaches based on single molecule localization break the diffraction barrier of conventional fluorescence microscopy, allowing for bioimaging with nanometer resolution. It remains a challenge, however, to precisely localize photon-limited single molecules in 3D. We have developed a new localization-based imaging technique achieving almost isotropic subdiffraction resolution in 3D. A tilted mirror is used to generate a side view in addition to the front view of activated single emitters, allowing their 3D localization to be precisely determined for superresolution imaging. Because both front and side views are in focus, this method is able to efficiently collect emitted photons. The technique is simple to implement on a commercial fluorescence microscope, and especially suitable for biological samples with photon-limited chromophores such as endogenously expressed photoactivatable fluorescent proteins. Moreover, this method is relatively resistant to optical aberration, as it requires only centroid determination for localization analysis. Here we demonstrate the application of this method to 3D imaging of bacterial protein distribution and neuron dendritic morphology with subdiffraction resolution.
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