1
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Adams MC, Schiltz C, Sun J, Hosford C, Johnson V, Pan H, Borbat P, Freed J, Thomason L, Court C, Court D, Chappie J. The crystal structure of bacteriophage λ RexA provides novel insights into the DNA binding properties of Rex-like phage exclusion proteins. Nucleic Acids Res 2024; 52:4659-4675. [PMID: 38554102 PMCID: PMC11077077 DOI: 10.1093/nar/gkae212] [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: 09/05/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 04/01/2024] Open
Abstract
RexA and RexB function as an exclusion system that prevents bacteriophage T4rII mutants from growing on Escherichia coli λ phage lysogens. Recent data established that RexA is a non-specific DNA binding protein that can act independently of RexB to bias the λ bistable switch toward the lytic state, preventing conversion back to lysogeny. The molecular interactions underlying these activities are unknown, owing in part to a dearth of structural information. Here, we present the 2.05-Å crystal structure of the λ RexA dimer, which reveals a two-domain architecture with unexpected structural homology to the recombination-associated protein RdgC. Modelling suggests that our structure adopts a closed conformation and would require significant domain rearrangements to facilitate DNA binding. Mutagenesis coupled with electromobility shift assays, limited proteolysis, and double electron-electron spin resonance spectroscopy support a DNA-dependent conformational change. In vivo phenotypes of RexA mutants suggest that DNA binding is not a strict requirement for phage exclusion but may directly contribute to modulation of the bistable switch. We further demonstrate that RexA homologs from other temperate phages also dimerize and bind DNA in vitro. Collectively, these findings advance our mechanistic understanding of Rex functions and provide new evolutionary insights into different aspects of phage biology.
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Affiliation(s)
- Myfanwy C Adams
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Carl J Schiltz
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Jing Sun
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | | | - Virginia M Johnson
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Hao Pan
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Peter P Borbat
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
- National Biomedical Resource for Advanced Electron Spin Resonance Spectroscopy, Cornell University, Ithaca, NY 14853, USA
| | - Jack H Freed
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
- National Biomedical Resource for Advanced Electron Spin Resonance Spectroscopy, Cornell University, Ithaca, NY 14853, USA
| | - Lynn C Thomason
- Center for Cancer Research, National Cancer Institute, Frederick, MD21702, USA
| | - Carolyn Court
- Center for Cancer Research, National Cancer Institute, Frederick, MD21702, USA
| | - Donald L Court
- Center for Cancer Research, National Cancer Institute, Frederick, MD21702, USA
| | - Joshua S Chappie
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
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2
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Patel PH, Maxwell KL. Prophages provide a rich source of antiphage defense systems. Curr Opin Microbiol 2023; 73:102321. [PMID: 37121062 DOI: 10.1016/j.mib.2023.102321] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/26/2023] [Accepted: 03/27/2023] [Indexed: 05/02/2023]
Abstract
Temperate phages are pervasive in nature, existing within bacterial cells in a form known as prophages. In this state, survival of the phage is intricately tied to the survival of the bacterial host. As a result, prophages often encode genes that increase bacterial fitness. One important way to increase survival is to provide defense against competing phages. Recent work reviewed here reveals that prophages provide a diverse and robust reservoir of antiphage defense systems that likely play a major role in bacterial-phage dynamics.
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Affiliation(s)
- Pramalkumar H Patel
- Department of Biochemistry, University of Toronto, MaRS West Tower, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Karen L Maxwell
- Department of Biochemistry, University of Toronto, MaRS West Tower, 661 University Avenue, Toronto, ON M5G 1M1, Canada.
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3
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Thomason LC, Costantino N, Li X, Court DL. Recombineering: Genetic Engineering in Escherichia coli Using Homologous Recombination. Curr Protoc 2023; 3:e656. [PMID: 36779782 PMCID: PMC10037674 DOI: 10.1002/cpz1.656] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
The bacterial chromosome and bacterial plasmids can be engineered in vivo by homologous recombination using either PCR products or synthetic double-stranded DNA (dsDNA) or single-stranded DNA as substrates. Multiple linear dsDNA molecules can be assembled into an intact plasmid. The technology of recombineering is possible because bacteriophage-encoded recombination proteins efficiently recombine sequences with homologies as short as 35 to 50 bases. Recombineering allows DNA sequences to be inserted or deleted without regard to the location of restriction sites and can also be used in combination with CRISPR/Cas targeting systems. © 2023 Wiley Periodicals LLC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. Basic Protocol: Making electrocompetent cells and transforming with linear DNA Support Protocol 1: Selection/counter-selections for genome engineering Support Protocol 2: Creating and screening for oligo recombinants by PCR Support Protocol 3: Other methods of screening for unselected recombinants Support Protocol 4: Curing recombineering plasmids containing a temperature-sensitive replication function Support Protocol 5: Removal of the prophage by recombineering Alternate Protocol 1: Using CRISPR/Cas9 as a counter-selection following recombineering Alternate Protocol 2: Assembly of linear dsDNA fragments into functional plasmids Alternate Protocol 3: Retrieval of alleles onto a plasmid by gap repair Alternate Protocol 4: Modifying multicopy plasmids with recombineering Support Protocol 6: Screening for unselected plasmid recombinants Alternate Protocol 5: Recombineering with an intact λ prophage Alternate Protocol 6: Targeting an infecting λ phage with the defective prophage strains.
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Affiliation(s)
- Lynn C. Thomason
- Molecular Control and Genetics Section, RNA Biology Laboratory, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland
| | - Nina Costantino
- formerly with Molecular Control and Genetics Section, RNA Biology Laboratory, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland
| | - Xintian Li
- Armata Pharmaceuticals, 4503 Glencoe Avenue, Marina del Rey, CA 90292
| | - Donald L. Court
- Emeritus, Molecular Control and Genetics Section, RNA Biology Laboratory, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland
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4
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Characterization of a New Temperate Escherichia coli Phage vB_EcoP_ZX5 and Its Regulatory Protein. Pathogens 2022; 11:pathogens11121445. [PMID: 36558779 PMCID: PMC9782041 DOI: 10.3390/pathogens11121445] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022] Open
Abstract
The study of the interaction between temperate phages and bacteria is vital to understand their role in the development of human diseases. In this study, a novel temperate Escherichia coli phage, vB_EcoP_ZX5, with a genome size of 39,565 bp, was isolated from human fecal samples. It has a short tail and belongs to the genus Uetakevirus and the family Podoviridae. Phage vB_EcoP_ZX5 encodes three lysogeny-related proteins (ORF12, ORF21, and ORF4) and can be integrated into the 3'-end of guaA of its host E. coli YO1 for stable transmission to offspring bacteria. Phage vB_EcoP_ZX5 in lysogenized E. coli YO1+ was induced spontaneously, with a free phage titer of 107 PFU/mL. The integration of vB_EcoP_ZX5 had no significant effect on growth, biofilm, environmental stress response, antibiotic sensitivity, adherence to HeLa cells, and virulence of E. coli YO1. The ORF4 anti-repressor, ORF12 integrase, and ORF21 repressors that affect the lytic-lysogenic cycle of vB_EcoP_ZX5 were verified by protein overexpression. We could tell from changes of the number of total phages and the transcription level of phage genes that repressor protein is the key determinant of lytic-to-lysogenic conversion, and anti-repressor protein promotes the conversion from lysogenic cycle to lytic cycle.
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5
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Silpe JE, Duddy OP, Papenfort K. Microbial Communication via Pyrazine Signaling: a New Class of Signaling Molecules Identified in
Vibrio cholerae. Isr J Chem 2022. [DOI: 10.1002/ijch.202200063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Justin E. Silpe
- Department of Molecular Biology Princeton University Princeton New Jersey USA
| | - Olivia P. Duddy
- Department of Molecular Biology Princeton University Princeton New Jersey USA
| | - Kai Papenfort
- Friedrich Schiller University Jena Institute of Microbiology, General Microbiology Winzerlaer Straße 2 07745 Jena Germany
- Microverse Cluster Friedrich Schiller University Jena Jena Germany
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6
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Miguel-Romero L, Alqasmi M, Bacarizo J, Tan JA, Cogdell RJ, Chen J, Byron O, Christie GE, Marina A, Penadés JR. Non-canonical Staphylococcus aureus pathogenicity island repression. Nucleic Acids Res 2022; 50:11109-11127. [PMID: 36200825 PMCID: PMC9638917 DOI: 10.1093/nar/gkac855] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 09/08/2022] [Accepted: 09/23/2022] [Indexed: 11/14/2022] Open
Abstract
Mobile genetic elements control their life cycles by the expression of a master repressor, whose function must be disabled to allow the spread of these elements in nature. Here, we describe an unprecedented repression-derepression mechanism involved in the transfer of Staphylococcus aureus pathogenicity islands (SaPIs). Contrary to the classical phage and SaPI repressors, which are dimers, the SaPI1 repressor StlSaPI1 presents a unique tetrameric conformation never seen before. Importantly, not just one but two tetramers are required for SaPI1 repression, which increases the novelty of the system. To derepress SaPI1, the phage-encoded protein Sri binds to and induces a conformational change in the DNA binding domains of StlSaPI1, preventing the binding of the repressor to its cognate StlSaPI1 sites. Finally, our findings demonstrate that this system is not exclusive to SaPI1 but widespread in nature. Overall, our results characterize a novel repression-induction system involved in the transfer of MGE-encoded virulence factors in nature.
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Affiliation(s)
- Laura Miguel-Romero
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, SW7 2AZ, UK
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, G12 8TA, UK
| | - Mohammed Alqasmi
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, G12 8TA, UK
- College of Applied Medical Sciences, Shaqra University, Shaqra City 15572, Saudi Arabia
| | - Julio Bacarizo
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, SW7 2AZ, UK
- Departamento de Ciencias Biomédicas, Universidad CEU Cardenal Herrera, 46113 Moncada, Spain
| | - Jason A Tan
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | | | - John Chen
- Infectious Diseases Translational Research Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, 5 Science Drive 2, Singapore
| | - Olwyn Byron
- School of Life Sciences, University of Glasgow, Glasgow, G12 8QQ,UK
| | - Gail E Christie
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Alberto Marina
- Instituto de Biomedicina de Valencia (IBV), CSIC and CIBER de Enfermedades Raras (CIBERER), Valencia, Spain
| | - José R Penadés
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, SW7 2AZ, UK
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7
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Lu Y, Voros Z, Borjas G, Hendrickson C, Shearwin K, Dunlap D, Finzi L. RNA polymerase efficiently transcribes DNA-scaffolded, cooperative bacteriophage repressor complexes. FEBS Lett 2022; 596:1994-2006. [PMID: 35819073 PMCID: PMC9491066 DOI: 10.1002/1873-3468.14447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 06/17/2022] [Accepted: 06/19/2022] [Indexed: 11/07/2022]
Abstract
DNA can act as a scaffold for the cooperative binding of protein oligomers. For example, the phage 186 CI repressor forms a wheel of seven dimers wrapped in DNA with specific binding sites, while phage λ CI repressor dimers bind to two well-separated sets of operators, forming a DNA loop. Atomic force microscopy was used to measure transcription elongation by E. coli RNA polymerase through these protein complexes. 186 CI, or λ CI, bound along unlooped DNA negligibly interfered with transcription by RNAP. Wrapped and looped topologies induced by these scaffolded, cooperatively bound repressor oligomers did not form significantly better roadblocks to transcription. Thus, despite binding with high affinity, these repressors are not effective roadblocks to transcription.
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Affiliation(s)
- Yue Lu
- Physics Department, Emory University, Atlanta, GA, USA
| | | | | | | | - Keith Shearwin
- Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | - David Dunlap
- Physics Department, Emory University, Atlanta, GA, USA
| | - Laura Finzi
- Physics Department, Emory University, Atlanta, GA, USA
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8
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Isolation and Characterization of a Novel Temperate Escherichia coli Bacteriophage, Kapi1, Which Modifies the O-Antigen and Contributes to the Competitiveness of Its Host during Colonization of the Murine Gastrointestinal Tract. mBio 2022; 13:e0208521. [PMID: 35073745 PMCID: PMC8787464 DOI: 10.1128/mbio.02085-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In this study, we describe the isolation and characterization of novel bacteriophage vB_EcoP_Kapi1 (Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the seroconverting phages of Shigella flexneri and clusters taxonomically with P22-like phages. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its host's O-antigen in multiple ways. Kapi1 displays unstable lysogeny, and we find that the lysogenic state is more stable during growth in simulated intestinal fluid. Furthermore, Kapi1 lysogens have a competitive advantage over their nonlysogenic counterparts both in vitro and in vivo, suggesting a role for Kapi1 during colonization. We thus report the use of MP1 and Kapi1 as a model system to explore the molecular mechanisms of mammalian colonization by E. coli to ask what the role(s) of prophages in this context might be. IMPORTANCE Although research exploring the microbiome has exploded in recent years, our understanding of the viral component of the microbiome is lagging far behind our understanding of the bacterial component. The vast majority of intestinal bacteria carry prophages integrated into their chromosomes, but most of these bacteriophages remain uncharacterized and unexplored. Here, we isolate and characterize a novel temperate bacteriophage infecting a commensal strain of Escherichia coli. We aim to explore the interactions between bacteriophages and their hosts in the context of the gastrointestinal tract, asking what role(s) temperate bacteriophages may play in growth and survival of bacteria in the gut. Understanding the fundamental biology of gut commensal bacteria can inform the development of novel antimicrobial or probiotic strategies for intestinal infections.
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9
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Bacteriophage self-counting in the presence of viral replication. Proc Natl Acad Sci U S A 2021; 118:2104163118. [PMID: 34916284 DOI: 10.1073/pnas.2104163118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2021] [Indexed: 11/18/2022] Open
Abstract
When host cells are in low abundance, temperate bacteriophages opt for dormant (lysogenic) infection. Phage lambda implements this strategy by increasing the frequency of lysogeny at higher multiplicity of infection (MOI). However, it remains unclear how the phage reliably counts infecting viral genomes even as their intracellular number increases because of replication. By combining theoretical modeling with single-cell measurements of viral copy number and gene expression, we find that instead of hindering lambda's decision, replication facilitates it. In a nonreplicating mutant, viral gene expression simply scales with MOI rather than diverging into lytic (virulent) and lysogenic trajectories. A similar pattern is followed during early infection by wild-type phage. However, later in the infection, the modulation of viral replication by the decision genes amplifies the initially modest gene expression differences into divergent trajectories. Replication thus ensures the optimal decision-lysis upon single-phage infection and lysogeny at higher MOI.
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10
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Pang Y, Liang J. Inferring initial state of the ancestral network of cellular fate decision: a case study of phage lambda. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4436-4439. [PMID: 34892204 PMCID: PMC8957294 DOI: 10.1109/embc46164.2021.9629880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Gene regulatory networks (GRNs) describe how gene expression is controlled by interactions among DNA and proteins. The decision network controlling prophage induction in phage lambda has served as a paradigm for studying decision control of cellular fate, which has broad implications for understanding phenomena such as embryo development, tissue regeneration, and tumorigenesis. The phage-lambda GRN dictates whether the phage enters the lytic mode or the lysogenic mode. In this work, we study the evolutionary origin of this GRN and explore the initial architecture of the proto-GRN, from which the modern GRN is evolved. Specifically, we examined the model of proto-GRN of phage-lambda containing one operator, from which the modern GRN with three operators evolved. We constructed 9 network architectures of the proto-GRNs by different combinations of the three operators OR3, OR2, OR1 and the three different genomic locations. We quantified the full stochastic behavior of each of these networks through exact computation of their steady-state probability landscapes using the Accurate Chemical Master Equation(ACME) algorithm. We further analyzed changes in the copy numbers of the two key proteins CI and Cro during prophage induction upon UV irradiation at different dosages. By examining the dynamic changes of the protein copy numbers upon different UV irradiations, our results show that the network in which OR1 located at the second site is the most probable architecture for the ancestral phage-lambda network. Our work can be extended for further analysis of the evolutionary trajectories of this cellular fate decision network.
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11
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Thomason LC, Schiltz CJ, Court C, Hosford CJ, Adams MC, Chappie JS, Court DL. Bacteriophage λ RexA and RexB Functions Assist the Transition from Lysogeny to Lytic Growth. Mol Microbiol 2021; 116:1044-1063. [PMID: 34379857 DOI: 10.1111/mmi.14792] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 11/26/2022]
Abstract
The CI and Cro repressors of bacteriophage λ create a bistable switch between lysogenic and lytic growth. In λ lysogens, CI repressor expressed from the PRM promoter blocks expression of the lytic promoters PL and PR to allow stable maintenance of the lysogenic state. When lysogens are induced, CI repressor is inactivated and Cro repressor is expressed from the lytic PR promoter. Cro repressor blocks PRM transcription and CI repressor synthesis to ensure that the lytic state proceeds. RexA and RexB proteins, like CI, are expressed from the PRM promoter in λ lysogens; RexB is also expressed from a second promoter, PLIT , embedded in rexA. Here we show that RexA binds CI repressor and assists the transition from lysogenic to lytic growth, using both intact lysogens and defective prophages with reporter genes under control of the lytic PL and PR promoters. Once lytic growth begins, if the bistable switch does return to the immune state, RexA expression lessens the probability that it will remain there, thus stabilizing the lytic state and activation of the lytic PL and PR promoters. RexB modulates the effect of RexA and may also help establish phage DNA replication as lytic growth ensues.
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Affiliation(s)
- Lynn C Thomason
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, 21702.,RNA Biology Laboratory, National Cancer Institute/Frederick Cancer Research and Development Center, Frederick, 21702
| | - Carl J Schiltz
- Department of Molecular Medicine, Cornell University, Ithaca, 14850.,Department of Biological Sciences and Center for Structural Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Carolyn Court
- RNA Biology Laboratory, National Cancer Institute/Frederick Cancer Research and Development Center, Frederick, 21702
| | - Christopher J Hosford
- Department of Molecular Medicine, Cornell University, Ithaca, 14850.,New England Biolabs, Inc, Ipswich, MA, USA
| | - Myfanwy C Adams
- Department of Molecular Medicine, Cornell University, Ithaca, 14850
| | - Joshua S Chappie
- Department of Molecular Medicine, Cornell University, Ithaca, 14850
| | - Donald L Court
- RNA Biology Laboratory, National Cancer Institute/Frederick Cancer Research and Development Center, Frederick, 21702
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12
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Correa AMS, Howard-Varona C, Coy SR, Buchan A, Sullivan MB, Weitz JS. Revisiting the rules of life for viruses of microorganisms. Nat Rev Microbiol 2021; 19:501-513. [PMID: 33762712 DOI: 10.1038/s41579-021-00530-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/15/2021] [Indexed: 02/01/2023]
Abstract
Viruses that infect microbial hosts have traditionally been studied in laboratory settings with a focus on either obligate lysis or persistent lysogeny. In the environment, these infection archetypes are part of a continuum that spans antagonistic to beneficial modes. In this Review, we advance a framework to accommodate the context-dependent nature of virus-microorganism interactions in ecological communities by synthesizing knowledge from decades of virology research, eco-evolutionary theory and recent technological advances. We discuss that nuanced outcomes, rather than the extremes of the continuum, are particularly likely in natural communities given variability in abiotic factors, the availability of suboptimal hosts and the relevance of multitrophic partnerships. We revisit the 'rules of life' in terms of how long-term infections shape the fate of viruses and microbial cells, populations and ecosystems.
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Affiliation(s)
| | | | - Samantha R Coy
- BioSciences Department, Rice University, Houston, TX, USA
| | - Alison Buchan
- Department of Microbiology, University of Tennessee, Knoxville, TN, USA.
| | - Matthew B Sullivan
- Department of Microbiology, The Ohio State University, Columbus, OH, USA. .,Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, Columbus, OH, USA.
| | - Joshua S Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA. .,School of Physics, Georgia Institute of Technology, Atlanta, GA, USA.
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13
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Gautam P, Kumar Sinha S. Anticipating response function in gene regulatory networks. J R Soc Interface 2021; 18:20210206. [PMID: 34062105 DOI: 10.1098/rsif.2021.0206] [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] [Indexed: 12/23/2022] Open
Abstract
The origin of an ordered genetic response of a complex and noisy biological cell is intimately related to the detailed mechanism of protein-DNA interactions present in a wide variety of gene regulatory (GR) systems. However, the quantitative prediction of genetic response and the correlation between the mechanism and the response curve is poorly understood. Here, we report in silico binding studies of GR systems to show that the transcription factor (TF) binds to multiple DNA sites with high cooperativity spreads from specific binding sites into adjacent non-specific DNA and bends the DNA. Our analysis is not limited only to the isolated model system but also can be applied to a system containing multiple interacting genes. The controlling role of TF oligomerization, TF-ligand interactions, and DNA looping for gene expression has been also characterized. The predictions are validated against detailed grand canonical Monte Carlo simulations and published data for the lac operon system. Overall, our study reveals that the expression of target genes can be quantitatively controlled by modulating TF-ligand interactions and the bending energy of DNA.
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Affiliation(s)
- Pankaj Gautam
- Theoretical and Computational Biophysical Chemistry Group, Department of Chemistry, Indian Institute of Technology, Ropar 140001, India
| | - Sudipta Kumar Sinha
- Theoretical and Computational Biophysical Chemistry Group, Department of Chemistry, Indian Institute of Technology, Ropar 140001, India
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14
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Restrepo-Pineda S, Pérez NO, Valdez-Cruz NA, Trujillo-Roldán MA. Thermoinducible expression system for producing recombinant proteins in Escherichia coli: advances and insights. FEMS Microbiol Rev 2021; 45:6223457. [PMID: 33844837 DOI: 10.1093/femsre/fuab023] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 04/09/2021] [Indexed: 12/13/2022] Open
Abstract
Recombinant protein (RP) production from Escherichia coli has been extensively studied to find strategies for increasing product yields. The thermoinducible expression system is commonly employed at the industrial level to produce various RPs which avoids the addition of chemical inducers, thus minimizing contamination risks. Multiple aspects of the molecular origin and biotechnological uses of its regulatory elements (pL/pR promoters and cI857 thermolabile repressor) derived from bacteriophage λ provide knowledge to improve the bioprocesses using this system. Here, we discuss the main aspects of the potential use of the λpL/pR-cI857 thermoinducible system for RP production in E. coli, focusing on the approaches of investigations that have contributed to the advancement of this expression system. Metabolic and physiological changes that occur in the host cells caused by heat stress and by RP overproduction are also described. Therefore, the current scenario and the future applications of systems that use heat to induce RP production is discussed to understand the relationship between the activation of the bacterial heat shock response, RP accumulation, and its possible aggregation to form inclusion bodies.
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Affiliation(s)
- Sara Restrepo-Pineda
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
| | - Néstor O Pérez
- Probiomed S.A. de C.V. Planta Tenancingo, Cruce de Carreteras Acatzingo-Zumpahuacan SN, 52400 Tenancingo, Estado de México, México
| | - Norma A Valdez-Cruz
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
| | - Mauricio A Trujillo-Roldán
- Unidad de Bioprocesos, Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
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15
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Meijer WJJ, Boer DR, Ares S, Alfonso C, Rojo F, Luque-Ortega JR, Wu LJ. Multiple Layered Control of the Conjugation Process of the Bacillus subtilis Plasmid pLS20. Front Mol Biosci 2021; 8:648468. [PMID: 33816561 PMCID: PMC8014075 DOI: 10.3389/fmolb.2021.648468] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 02/08/2021] [Indexed: 11/24/2022] Open
Abstract
Bacterial conjugation is the main horizontal gene transfer route responsible for the spread of antibiotic resistance, virulence and toxin genes. During conjugation, DNA is transferred from a donor to a recipient cell via a sophisticated channel connecting the two cells. Conjugation not only affects many different aspects of the plasmid and the host, ranging from the properties of the membrane and the cell surface of the donor, to other developmental processes such as competence, it probably also poses a burden on the donor cell due to the expression of the large number of genes involved in the conjugation process. Therefore, expression of the conjugation genes must be strictly controlled. Over the past decade, the regulation of the conjugation genes present on the conjugative Bacillus subtilis plasmid pLS20 has been studied using a variety of methods including genetic, biochemical, biophysical and structural approaches. This review focuses on the interplay between RcopLS20, RappLS20 and Phr*pLS20, the proteins that control the activity of the main conjugation promoter Pc located upstream of the conjugation operon. Proper expression of the conjugation genes requires the following two fundamental elements. First, conjugation is repressed by default and an intercellular quorum-signaling system is used to sense conditions favorable for conjugation. Second, different layers of regulation act together to repress the Pc promoter in a strict manner but allowing rapid activation. During conjugation, ssDNA is exported from the cell by a membrane-embedded DNA translocation machine. Another membrane-embedded DNA translocation machine imports ssDNA in competent cells. Evidences are reviewed indicating that conjugation and competence are probably mutually exclusive processes. Some of the questions that remain unanswered are discussed.
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Affiliation(s)
- Wilfried J J Meijer
- Laboratory 402, Centro de Biología Molecular "Severo Ochoa" (CSIC-UAM), Universidad Autónoma, Canto Blanco, Madrid, Spain
| | | | - Saúl Ares
- Laboratory 35, C. Grupo Interdisciplinar de Sistemas Complejos and Departamento de Biología de Sistemas, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Carlos Alfonso
- Laboratory B08, Systems Biochemistry of Bacterial Division Lab, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Fernando Rojo
- Laboratory 216, Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, Madrid, Spain
| | - Juan R Luque-Ortega
- Laboratory S07, Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas (CSIC), Madrid, Spain
| | - Ling Juan Wu
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
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16
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Peña JM, Prezioso SM, McFarland KA, Kambara TK, Ramsey KM, Deighan P, Dove SL. Control of a programmed cell death pathway in Pseudomonas aeruginosa by an antiterminator. Nat Commun 2021; 12:1702. [PMID: 33731715 PMCID: PMC7969949 DOI: 10.1038/s41467-021-21941-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 02/19/2021] [Indexed: 01/29/2023] Open
Abstract
In Pseudomonas aeruginosa the alp system encodes a programmed cell death pathway that is switched on in a subset of cells in response to DNA damage and is linked to the virulence of the organism. Here we show that the central regulator of this pathway, AlpA, exerts its effects by acting as an antiterminator rather than a transcription activator. In particular, we present evidence that AlpA positively regulates the alpBCDE cell lysis genes, as well as genes in a second newly identified target locus, by recognizing specific DNA sites within the promoter, then binding RNA polymerase directly and allowing it to bypass intrinsic terminators positioned downstream. AlpA thus functions in a mechanistically unusual manner to control the expression of virulence genes in this opportunistic pathogen.
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Affiliation(s)
- Jennifer M Peña
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Samantha M Prezioso
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kirsty A McFarland
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Tracy K Kambara
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Kathryn M Ramsey
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.,Departments of Cell and Molecular Biology and Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | | | - Simon L Dove
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.
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17
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Abstract
Enterohemorrhagic E. coli is a significant human pathogen that can cause severe disease due to the release of Shiga toxins. The toxins are encoded within lysogenic bacteriophage and controlled by antitermination of the phage late promoter, PR′. This promoter is always active, but terminated immediately downstream during lysogeny. A byproduct of antitermination regulation is transcription of a short RNA that is thought to be nonfunctional. Here we demonstrate that in Shiga toxin-encoding phages, this short RNA is a Hfq-binding regulatory small RNA. The small RNA represses toxin production threefold under lysogenic conditions and promotes high cell density growth. Lysogenic bacteriophages are highly abundant and our results suggest that antiterminated phage promoters may be a rich source of regulatory RNAs. Enterohemorrhagic Escherichia coli is a significant human pathogen that causes disease ranging from hemorrhagic colitis to hemolytic uremic syndrome. The latter can lead to potentially fatal renal failure and is caused by the release of Shiga toxins that are encoded within lambdoid bacteriophages. The toxins are encoded within the late transcript of the phage and are regulated by antitermination of the PR′ late promoter during lytic induction of the phage. During lysogeny, the late transcript is prematurely terminated at tR′ immediately downstream of PR′, generating a short RNA that is a byproduct of antitermination regulation. We demonstrate that this short transcript binds the small RNA chaperone Hfq, and is processed into a stable 74-nt regulatory small RNA that we have termed StxS. StxS represses expression of Shiga toxin 1 under lysogenic conditions through direct interactions with the stx1AB transcript. StxS acts in trans to activate expression of the general stress response sigma factor, RpoS, through direct interactions with an activating seed sequence within the 5′ UTR. Activation of RpoS promotes high cell density growth under nutrient-limiting conditions. Many phages utilize antitermination to regulate the lytic/lysogenic switch and our results demonstrate that short RNAs generated as a byproduct of this regulation can acquire regulatory small RNA functions that modulate host fitness.
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18
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Phillips R, Belliveau NM, Chure G, Garcia HG, Razo-Mejia M, Scholes C. Figure 1 Theory Meets Figure 2 Experiments in the Study of Gene Expression. Annu Rev Biophys 2020; 48:121-163. [PMID: 31084583 DOI: 10.1146/annurev-biophys-052118-115525] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It is tempting to believe that we now own the genome. The ability to read and rewrite it at will has ushered in a stunning period in the history of science. Nonetheless, there is an Achilles' heel exposed by all of the genomic data that has accrued: We still do not know how to interpret them. Many genes are subject to sophisticated programs of transcriptional regulation, mediated by DNA sequences that harbor binding sites for transcription factors, which can up- or down-regulate gene expression depending upon environmental conditions. This gives rise to an input-output function describing how the level of expression depends upon the parameters of the regulated gene-for instance, on the number and type of binding sites in its regulatory sequence. In recent years, the ability to make precision measurements of expression, coupled with the ability to make increasingly sophisticated theoretical predictions, has enabled an explicit dialogue between theory and experiment that holds the promise of covering this genomic Achilles' heel. The goal is to reach a predictive understanding of transcriptional regulation that makes it possible to calculate gene expression levels from DNA regulatory sequence. This review focuses on the canonical simple repression motif to ask how well the models that have been used to characterize it actually work. We consider a hierarchy of increasingly sophisticated experiments in which the minimal parameter set learned at one level is applied to make quantitative predictions at the next. We show that these careful quantitative dissections provide a template for a predictive understanding of the many more complex regulatory arrangements found across all domains of life.
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Affiliation(s)
- Rob Phillips
- Department of Physics, California Institute of Technology, Pasadena, California, USA; .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Nathan M Belliveau
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.,Department of Biology, University of Washington, Seattle, Washington 98195, USA
| | - Griffin Chure
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Hernan G Garcia
- Department of Molecular & Cell Biology, Department of Physics, Biophysics Graduate Group, and Institute for Quantitative Biosciences-QB3, University of California, Berkeley, California, USA
| | - Manuel Razo-Mejia
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Clarissa Scholes
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, USA
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19
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Thomason LC, Morrill K, Murray G, Court C, Shafer B, Schneider TD, Court DL. Elements in the λ immunity region regulate phage development: beyond the 'Genetic Switch'. Mol Microbiol 2019; 112:1798-1813. [PMID: 31545538 PMCID: PMC8103288 DOI: 10.1111/mmi.14394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2019] [Indexed: 01/16/2023]
Abstract
Genetic elements in the bacteriophage λ immunity region contribute to stable maintenance and synchronous induction of the integrated Escherichia coli prophage. There is a bistable switch between lysogenic and lytic growth that is orchestrated by the CI and Cro repressors acting on the lytic (PL and PR ) and lysogenic (PRM ) promoters, referred to as the Genetic Switch. Other less well-characterized elements in the phage immunity region include the PLIT promoter and the immunity terminator, TIMM . The PLIT promoter is repressed by the bacterial LexA protein in λ lysogens. LexA repressor, like the λ CI repressor, is inactivated during the SOS response to DNA damage, and this regulation ensures that the PLIT promoter and the lytic PL and PR promoters are synchronously activated. Proper RexA and RexB protein levels are critical for the switch from lysogeny to lytic growth. Mutation of PLIT reduces RexB levels relative to RexA, compromising cellular energetics and causing a 10-fold reduction in lytic phage yield. The RexA and RexB proteins interact with themselves and each other in a bacterial two-hybrid system. We also find that the transcription terminator, TIMM , is a Rho-independent, intrinsic terminator. Inactivation of TIMM has minimal effect on λ lysogenization or prophage induction.
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Affiliation(s)
- Lynn C Thomason
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Kathleen Morrill
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Gillian Murray
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Carolyn Court
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Brenda Shafer
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Thomas D Schneider
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
| | - Donald L Court
- RNA Biology Laboratory, National Cancer Institute, Frederick, MD, 21702, USA
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20
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Laganenka L, Sander T, Lagonenko A, Chen Y, Link H, Sourjik V. Quorum Sensing and Metabolic State of the Host Control Lysogeny-Lysis Switch of Bacteriophage T1. mBio 2019; 10:e01884-19. [PMID: 31506310 PMCID: PMC6737242 DOI: 10.1128/mbio.01884-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 08/20/2019] [Indexed: 12/24/2022] Open
Abstract
Bacterial viruses, or bacteriophages, are highly abundant in the biosphere and have a major impact on microbial populations. Many examples of phage interactions with their hosts, including establishment of dormant lysogenic and active lytic states, have been characterized at the level of the individual cell. However, much less is known about the dependence of these interactions on host metabolism and signal exchange within bacterial communities. In this report, we describe a lysogenic state of the enterobacterial phage T1, previously known as a classical lytic phage, and characterize the underlying regulatory circuitry. We show that the transition from lysogeny to lysis depends on bacterial population density, perceived via interspecies autoinducer 2. Lysis is further controlled by the metabolic state of the cell, mediated by the cyclic-3',5'-AMP (cAMP) receptor protein (CRP) of the host. We hypothesize that such combinations of cell density and metabolic sensing may be common in phage-host interactions.IMPORTANCE The dynamics of microbial communities are heavily shaped by bacterium-bacteriophage interactions. But despite the apparent importance of bacteriophages, our understanding of the mechanisms controlling phage dynamics in bacterial populations, and particularly of the differences between the decisions that are made in the dormant lysogenic and active lytic states, remains limited. In this report, we show that enterobacterial phage T1, previously described as a lytic phage, is able to undergo lysogeny. We further demonstrate that the lysogeny-to-lysis decision occurs in response to changes in the density of the bacterial population, mediated by interspecies quorum-sensing signal AI-2, and in the metabolic state of the cell, mediated by cAMP receptor protein. We hypothesize that this strategy enables the phage to maximize its chances of self-amplification and spreading in bacterial population upon induction of the lytic cycle and that it might be common in phage-host interactions.
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Affiliation(s)
- Leanid Laganenka
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Timur Sander
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | | | - Yu Chen
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Hannes Link
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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21
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Ciges-Tomas JR, Alite C, Humphrey S, Donderis J, Bowring J, Salvatella X, Penadés JR, Marina A. The structure of a polygamous repressor reveals how phage-inducible chromosomal islands spread in nature. Nat Commun 2019; 10:3676. [PMID: 31417084 PMCID: PMC6695447 DOI: 10.1038/s41467-019-11504-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 07/17/2019] [Indexed: 11/10/2022] Open
Abstract
Stl is a master repressor encoded by Staphylococcus aureus pathogenicity islands (SaPIs) that maintains integration of these elements in the bacterial chromosome. After infection or induction of a resident helper phage, SaPIs are de-repressed by specific interactions of phage proteins with Stl. SaPIs have evolved a fascinating mechanism to ensure their promiscuous transfer by targeting structurally unrelated proteins performing identically conserved functions for the phage. Here we decipher the molecular mechanism of this elegant strategy by determining the structure of SaPIbov1 Stl alone and in complex with two structurally unrelated dUTPases from different S. aureus phages. Remarkably, SaPIbov1 Stl has evolved different domains implicated in DNA and partner recognition specificity. This work presents the solved structure of a SaPI repressor protein and the discovery of a modular repressor that acquires multispecificity through domain recruiting. Our results establish the mechanism that allows widespread dissemination of SaPIs in nature.
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Affiliation(s)
- J Rafael Ciges-Tomas
- Instituto de Biomedicina de Valencia (IBV-CSIC) and CIBER de Enfermedades Raras (CIBERER), Valencia, 46010, Spain
| | - Christian Alite
- Instituto de Biomedicina de Valencia (IBV-CSIC) and CIBER de Enfermedades Raras (CIBERER), Valencia, 46010, Spain
| | - Suzanne Humphrey
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - J Donderis
- Instituto de Biomedicina de Valencia (IBV-CSIC) and CIBER de Enfermedades Raras (CIBERER), Valencia, 46010, Spain
| | - Janine Bowring
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK
| | - Xavier Salvatella
- ICREA and Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, 08010, Spain
| | - José R Penadés
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK.
| | - Alberto Marina
- Instituto de Biomedicina de Valencia (IBV-CSIC) and CIBER de Enfermedades Raras (CIBERER), Valencia, 46010, Spain.
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22
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Multiple Mechanisms Are Involved in Repression of Filamentous Phage SW1 Transcription by the DNA-Binding Protein FpsR. J Mol Biol 2019; 431:1113-1126. [DOI: 10.1016/j.jmb.2019.01.040] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 01/16/2019] [Accepted: 01/31/2019] [Indexed: 01/21/2023]
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23
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Abstract
The study of bacteriophages (phages) and prophages has provided key insights into almost every cellular process as well as led to the discovery of unexpected new mechanisms and the development of valuable tools. This is exemplified for RNA-based regulation. For instance, the characterization and exploitation of the antiphage CRISPR (clustered regularly interspaced short palindromic repeat) systems is revolutionizing molecular biology. Phage-encoded proteins such as the RNA-binding MS2 protein, which is broadly used to isolate tagged RNAs, also have been developed as valuable tools. Hfq, the RNA chaperone protein central to the function of many base-pairing small RNAs (sRNAs), was first characterized as a bacterial host factor required for Qβ phage replication. The ongoing studies of RNAs are continuing to reveal regulatory connections between infecting phages, prophages, and bacteria and to provide novel insights. There are bacterial and prophage sRNAs that regulate prophage genes, which impact bacterial virulence as well as bacterial cell killing. Conversely, phage- and prophage-encoded sRNAs modulate the expression of bacterial genes modifying metabolism. An interesting subcategory of the prophage-encoded sRNAs are sponge RNAs that inhibit the activities of bacterial-encoded sRNAs. Phages also affect posttranscriptional regulation in bacteria through proteins that inhibit or alter the activities of key bacterial proteins involved in posttranscriptional regulation. However, what is most exciting about phage and prophage research, given the millions of phage-encoded genes that have not yet been characterized, is the vast potential for discovering new RNA regulators and novel mechanisms and for gaining insight into the evolution of regulatory RNAs.
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24
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Schwendener S, Perreten V. The integrase of the Macrococcus caseolyticus
resistance island mecD
(McRI
mecD
) inserts DNA site-specifically into Staphylococcus
and Bacillus
chromosomes. Mol Microbiol 2018; 110:455-468. [DOI: 10.1111/mmi.14112] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Sybille Schwendener
- Institute of Veterinary Bacteriology, Vetsuisse Faculty; University of Bern; Bern Switzerland
| | - Vincent Perreten
- Institute of Veterinary Bacteriology, Vetsuisse Faculty; University of Bern; Bern Switzerland
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25
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Manning KA, Quiles-Puchalt N, Penadés JR, Dokland T. A novel ejection protein from bacteriophage 80α that promotes lytic growth. Virology 2018; 525:237-247. [PMID: 30308422 DOI: 10.1016/j.virol.2018.09.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 09/28/2018] [Accepted: 09/28/2018] [Indexed: 12/30/2022]
Abstract
Many staphylococcal bacteriophages encode a minor capsid protein between the genes for the portal and scaffolding proteins. In Staphylococcus aureus bacteriophage 80α, this protein, called gp44, is essential for the production of viable phage, but dispensable for the phage-mediated mobilization of S. aureus pathogenicity islands. We show here that gp44 is not required for capsid assembly, DNA packaging or ejection of the DNA, nor for generalized transduction of plasmids. An 80α Δ44 mutant could be complemented in trans by gp44 expressed from a plasmid, indicating that gp44 plays a post-injection role in the host. Our results show that gp44 is an ejection (pilot) protein that is involved in deciding the fate of the phage DNA after injection. Our data are consistent with a model in which gp44 acts as a regulatory protein that promotes progression to the lytic cycle.
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Affiliation(s)
- Keith A Manning
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Nuria Quiles-Puchalt
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - José R Penadés
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Terje Dokland
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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26
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The Bacteriophage Lambda CII Phenotypes for Complementation, Cellular Toxicity and Replication Inhibition Are Suppressed in cII-oop Constructs Expressing the Small RNA OOP. Viruses 2018. [PMID: 29518935 PMCID: PMC5869508 DOI: 10.3390/v10030115] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The temperate bacteriophage lambda (λ) CII protein is a positive regulator of transcription from promoter pE, a component of the lysogenic response. The expression of cII was examined in vectors devoid of phage transcription-modulating elements. Their removal enabled evaluating if the expression of the small RNA OOP, on its own, could suppress CII activities, including complementing for a lysogenic response, cell toxicity and causing rapid cellular loss of ColE1 plasmids. The results confirm that OOP RNA expression from the genetic element pO-oop-to can prevent the ability of plasmid-encoded CII to complement for a lysogenic response, suggesting that it serves as a powerful regulatory pivot in λ development. Plasmids with a pO promoter sequence of 45 nucleotides (pO45), containing the −10 and −35 regions for oop, were non-functional; whereas, plasmids with pO94 prevented CII complementation, CII-dependent plasmid loss and suppressed CII toxicity, suggesting the pO promoter has an extended DNA sequence. All three CII activities were eliminated by the deletion of the COOH-terminal 20 amino acids of CII. Host mutations in the hflA locus, in pcnB and in rpoB influenced CII activities. These studies suggest that the COOH-terminal end of CII likely interacts with the β-subunit of RNA polymerase.
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27
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Jamrichová D, Tišáková L, Jarábková V, Godány A. How to approach heterogeneous protein expression for biotechnological use: An overview. NOVA BIOTECHNOLOGICA ET CHIMICA 2017. [DOI: 10.1515/nbec-2017-0001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
AbstractProduction of recombinant proteins in Escherichia coli expression systems has shown many advantages, as well as disadvantages, especially for biotechnological and other down-stream applications. The choice of an appropriate vector depends on the gene, to be cloned for purification procedures and other analyses. Selection of a suitable production strain plays an important role in the preparation of recombinant proteins. The main criteria for the selection of the host organism are the properties of the recombinant produced protein, its subsequent use and the total amount desired. The most common problems in eukaryotic gene expression and recombinant proteins purification are, for instance, post-translational modifications, formation of disulphide bonds, or inclusion bodies. Obtaining a purified protein is a key step enabling further characterization of its role in the biological system. Moreover, methods of protein purification have been developed in parallel with the discovery of proteins and the need for their studies and applications. After protein purification, and also between the individual purification steps, it is necessary to test protein stability under different conditions over time. Shortly, all the essential points have been briefly discussed, which could be encountered during production and purification of a recombinant protein of interest, especially from eukaryotic source and expressed heterogeneously in prokaryotic production system.
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28
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Trinh JT, Székely T, Shao Q, Balázsi G, Zeng L. Cell fate decisions emerge as phages cooperate or compete inside their host. Nat Commun 2017; 8:14341. [PMID: 28165024 PMCID: PMC5303824 DOI: 10.1038/ncomms14341] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/19/2016] [Indexed: 01/02/2023] Open
Abstract
The system of the bacterium Escherichia coli and its virus, bacteriophage lambda, is paradigmatic for gene regulation in cell-fate development, yet insight about its mechanisms and complexities are limited due to insufficient resolution of study. Here we develop a 4-colour fluorescence reporter system at the single-virus level, combined with computational models to unravel both the interactions between phages and how individual phages determine cellular fates. We find that phages cooperate during lysogenization, compete among each other during lysis, and that confusion between the two pathways occasionally occurs. Additionally, we observe that phage DNAs have fluctuating cellular arrival times and vie for resources to replicate, enabling the interplay during different developmental paths, where each phage genome may make an individual decision. These varied strategies could separate the selection for replication-optimizing beneficial mutations during lysis from sequence diversification during lysogeny, allowing rapid adaptation of phage populations for various environments.
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Affiliation(s)
- Jimmy T. Trinh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
- Center for Phage Technology, Texas A&M University, College Station, Texas 77843, USA
| | - Tamás Székely
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, USA
| | - Qiuyan Shao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
- Center for Phage Technology, Texas A&M University, College Station, Texas 77843, USA
| | - Gábor Balázsi
- The Louis and Beatrice Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, New York 11794, USA
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 11794, USA
| | - Lanying Zeng
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
- Center for Phage Technology, Texas A&M University, College Station, Texas 77843, USA
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29
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Das A, Biswas M. Changes in the Functional Activity of Phi11 Cro Protein is Mediated by Various Ions. Protein J 2016; 35:407-415. [DOI: 10.1007/s10930-016-9684-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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30
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Shao Q, Trinh JT, McIntosh CS, Christenson B, Balázsi G, Zeng L. Lysis-lysogeny coexistence: prophage integration during lytic development. Microbiologyopen 2016; 6. [PMID: 27530202 PMCID: PMC5300877 DOI: 10.1002/mbo3.395] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 06/30/2016] [Indexed: 11/11/2022] Open
Abstract
The infection of Escherichia coli cells by bacteriophage lambda results in bifurcated means of propagation, where the phage decides between the lytic and lysogenic pathways. Although traditionally thought to be mutually exclusive, increasing evidence suggests that this lysis-lysogeny decision is more complex than once believed, but exploring its intricacies requires an improved resolution of study. Here, with a newly developed fluorescent reporter system labeling single phage and E. coli DNAs, these two distinct pathways can be visualized by following the DNA movements in vivo. Surprisingly, we frequently observed an interesting "lyso-lysis" phenomenon in lytic cells, where phage integrates its DNA into the host, a characteristic event of the lysogenic pathway, followed by cell lysis. Furthermore, the frequency of lyso-lysis increases with the number of infecting phages, and specifically, with CII activity. Moreover, in lytic cells, the integration site attB on the E. coli genome migrates toward the polar region over time, leading to more spatial overlap with the phage DNA and frequent colocalization/collision of attB and phage DNA, possibly contributing to a higher chance for DNA integration.
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Affiliation(s)
- Qiuyan Shao
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.,Center for Phage Technology, Texas A&M University, College Station, Texas, USA
| | - Jimmy T Trinh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.,Center for Phage Technology, Texas A&M University, College Station, Texas, USA
| | - Colby S McIntosh
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Brita Christenson
- Department of Biology and Biochemistry, University of Northwestern - St. Paul, St. Paul, Minnesota, USA
| | - Gábor Balázsi
- Laufer Center for Physical & Quantitative Biology, Stony Brook University, Stony Brook, New York, USA.,Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, USA
| | - Lanying Zeng
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.,Center for Phage Technology, Texas A&M University, College Station, Texas, USA
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Valle A, Hervis Y, Socas L, Canet L, Faheem M, Barbosa J, Lanio M, Pazos I. The multigene families of actinoporins (part II): Strategies for heterologous production in Escherichia coli. Toxicon 2016; 118:64-81. [DOI: 10.1016/j.toxicon.2016.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 03/24/2016] [Indexed: 11/26/2022]
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Bandiera L, Furini S, Giordano E. Phenotypic Variability in Synthetic Biology Applications: Dealing with Noise in Microbial Gene Expression. Front Microbiol 2016; 7:479. [PMID: 27092132 PMCID: PMC4824758 DOI: 10.3389/fmicb.2016.00479] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/22/2016] [Indexed: 01/08/2023] Open
Abstract
The stochasticity due to the infrequent collisions among low copy-number molecules within the crowded cellular compartment is a feature of living systems. Single cell variability in gene expression within an isogenic population (i.e., biological noise) is usually described as the sum of two independent components: intrinsic and extrinsic stochasticity. Intrinsic stochasticity arises from the random occurrence of events inherent to the gene expression process (e.g., the burst-like synthesis of mRNA and protein molecules). Extrinsic fluctuations reflect the state of the biological system and its interaction with the intra and extracellular environments (e.g., concentration of available polymerases, ribosomes, metabolites, and micro-environmental conditions). A better understanding of cellular noise would help synthetic biologists design gene circuits with well-defined functional properties. In silico modeling has already revealed several aspects of the network topology’s impact on noise properties; this information could drive the selection of biological parts and the design of reliably engineered pathways. Importantly, while optimizing artificial gene circuitry for industrial applications, synthetic biology could also elucidate the natural mechanisms underlying natural phenotypic variability. In this review, we briefly summarize the functional roles of noise in unicellular organisms and address their relevance to synthetic network design. We will also consider how noise might influence the selection of network topologies supporting reliable functions, and how the variability of cellular events might be exploited when designing innovative biotechnology applications.
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Affiliation(s)
- Lucia Bandiera
- Laboratory of Cellular and Molecular Engineering "S. Cavalcanti", Department of Electrical, Electronic and Information Engineering "G. Marconi", University of Bologna Cesena, Italy
| | - Simone Furini
- Department of Medical Biotechnologies, University of Siena Siena, Italy
| | - Emanuele Giordano
- Laboratory of Cellular and Molecular Engineering "S. Cavalcanti", Department of Electrical, Electronic and Information Engineering "G. Marconi", University of BolognaCesena, Italy; BioEngLab, Health Science and Technology, Interdepartmental Center for Industrial Research, University of BolognaCesena, Italy; Advanced Research Center on Electronic Systems, University of BolognaCesena, Italy
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Thomason LC, Court DL. Evidence that bacteriophage λ lysogens may induce in response to the proton motive force uncoupler CCCP. FEMS Microbiol Lett 2016; 363:fnv244. [PMID: 26705574 PMCID: PMC4809988 DOI: 10.1093/femsle/fnv244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/30/2015] [Accepted: 12/19/2015] [Indexed: 11/13/2022] Open
Abstract
We describe a genetic β-galactoside reporter system using a disk diffusion assay on MacConkey Lactose agar petri plates to monitor maintenance of the bacteriophage λ prophage state and viral induction in Escherichia coli K-12. Evidence is presented that the phage λ major lytic promoters, pL and pR, are activated when cells containing the reporters are exposed to the energy poison carbonyl cyanide m-chlorophenyl hydrazine, CCCP. This uncoupler of oxidative phosphorylation inhibits ATP synthesis by collapsing the proton motive force. Expression of the λ lytic promoters in response to CCCP requires host RecA function and an autocleavable CI repressor, as does SOS induction of the λ prophage that occurs by a DNA damage-dependent pathway. λ Cro function is required for CCCP-mediated activation of the λ lytic promoters. CCCP does not induce an sfi-lacZ SOS reporter.
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Affiliation(s)
- Lynn C Thomason
- Basic Science Program, GRCBL-Molecular Control & Genetics Section, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21702, USA Gene Regulation and Chromosome Biology Laboratory, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Donald L Court
- Gene Regulation and Chromosome Biology Laboratory, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
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Prophage-Encoded Staphylococcal Enterotoxin A: Regulation of Production in Staphylococcus aureus Strains Representing Different Sea Regions. Toxins (Basel) 2015; 7:5359-76. [PMID: 26690218 PMCID: PMC4690139 DOI: 10.3390/toxins7124889] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 11/26/2015] [Accepted: 11/30/2015] [Indexed: 11/17/2022] Open
Abstract
The present study investigates the nature of the link between the staphylococcal enterotoxin A (SEA) gene and the lifecycle of Siphoviridae bacteriophages, including the origin of strain variation regarding SEA production after prophage induction. Five strains representing three different genetic lines of the sea region were studied under optimal and prophage-induced growth conditions and the Siphoviridae lifecycle was followed through the phage replicative form copies and transcripts of the lysogenic repressor, cro. The role of SOS response on prophage induction was addressed through recA transcription in a recA-disruption mutant. Prophage induction was found to increase the abundance of the phage replicative form, the sea gene copies and transcripts and enhance SEA production. Sequence analysis of the sea regions revealed that observed strain variances were related to strain capacity for prophage induction, rather than sequence differences in the sea region. The impact of SOS response activation on the phage lifecycle was demonstrated by the absence of phage replicative form copies in the recA-disruption mutant after prophage induction. From this study it emerges that all aspects of SEA-producing strain, the Siphoviridae phage and the food environment must be considered when evaluating SEA-related hazards.
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Schultze T, Hilker R, Mannala GK, Gentil K, Weigel M, Farmani N, Windhorst AC, Goesmann A, Chakraborty T, Hain T. A detailed view of the intracellular transcriptome of Listeria monocytogenes in murine macrophages using RNA-seq. Front Microbiol 2015; 6:1199. [PMID: 26579105 PMCID: PMC4627465 DOI: 10.3389/fmicb.2015.01199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/15/2015] [Indexed: 01/21/2023] Open
Abstract
Listeria monocytogenes is a bacterial pathogen and causative agent for the foodborne infection listeriosis, which is mainly a threat for pregnant, elderly, or immunocompromised individuals. Due to its ability to invade and colonize diverse eukaryotic cell types including cells from invertebrates, L. monocytogenes has become a well-established model organism for intracellular growth. Almost 10 years ago, we and others presented the first whole-genome microarray-based intracellular transcriptome of L. monocytogenes. With the advent of newer technologies addressing transcriptomes in greater detail, we revisit this work, and analyze the intracellular transcriptome of L. monocytogenes during growth in murine macrophages using a deep sequencing based approach. We detected 656 differentially expressed genes of which 367 were upregulated during intracellular growth in macrophages compared to extracellular growth in Brain Heart Infusion broth. This study confirmed ∼64% of all regulated genes previously identified by microarray analysis. Many of the regulated genes that were detected in the current study involve transporters for various metals, ions as well as complex sugars such as mannose. We also report changes in antisense transcription, especially upregulations during intracellular bacterial survival. A notable finding was the detection of regulatory changes for a subset of temperate A118-like prophage genes, thereby shedding light on the transcriptional profile of this bacteriophage during intracellular growth. In total, our study provides an updated genome-wide view of the transcriptional landscape of L. monocytogenes during intracellular growth and represents a rich resource for future detailed analysis.
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Affiliation(s)
- Tilman Schultze
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Rolf Hilker
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany ; Bioinformatics and Systems Biology, Justus Liebig University Giessen, Germany
| | - Gopala K Mannala
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Katrin Gentil
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Markus Weigel
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Neda Farmani
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Anita C Windhorst
- Institute of Medical Informatics, Justus Liebig University Giessen, Germany
| | - Alexander Goesmann
- Bioinformatics and Systems Biology, Justus Liebig University Giessen, Germany
| | - Trinad Chakraborty
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
| | - Torsten Hain
- Institute of Medical Microbiology, Justus Liebig University Giessen, Germany
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36
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Carrasco B, Escobedo S, Alonso JC, Suárez JE. Modulation of Lactobacillus casei bacteriophage A2 lytic/lysogenic cycles by binding of Gp25 to the early lytic mRNA. Mol Microbiol 2015; 99:328-37. [PMID: 26417647 DOI: 10.1111/mmi.13234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2015] [Indexed: 11/27/2022]
Abstract
The genetic switch of Lactobacillus casei bacteriophage A2 is regulated by the CI protein, which represses the early lytic promoter PR and Cro that abolishes expression from the lysogenic promoter PL . Lysogens contain equivalent cI and cro-gp25 mRNA concentrations, i.e., CI only partially represses P(R), predicting a lytic cycle dominance. However, A2 generates stable lysogens. This may be due to Gp25 binding to the cro-gp25 mRNA between the ribosomal binding site and the cro start codon, which abolishes its translation. Upon lytic cycle induction, CI is partially degraded, cro-gp25 mRNA levels increase, and Cro accumulates, launching viral progeny production. The concomitant concentration increase of Gp25 restricts cro mRNA translation, which, together with the low but detectable levels of CI late during the lytic cycle, promotes reentry of part of the cell population into the lysogenic cycle, thus explaining the low proportion of L. casei lysogens that become lysed (∼ 1%). A2 shares its genetic switch structure with many other Firmicutes phages. The data presented may constitute a model of how these phages make the decision for lysis versus lysogeny.
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Affiliation(s)
- Begoña Carrasco
- Area de Microbiología/Instituto Universitario de Biotecnología, Universidad de Oviedo, Oviedo, Spain.,Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Susana Escobedo
- Area de Microbiología/Instituto Universitario de Biotecnología, Universidad de Oviedo, Oviedo, Spain.,Instituto de Productos Lacteos de Asturias (IPLA-CSIC), Villaviciosa, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Juan E Suárez
- Area de Microbiología/Instituto Universitario de Biotecnología, Universidad de Oviedo, Oviedo, Spain.,Instituto de Productos Lacteos de Asturias (IPLA-CSIC), Villaviciosa, Spain
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38
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Ramachandran G, Singh PK, Luque-Ortega JR, Yuste L, Alfonso C, Rojo F, Wu LJ, Meijer WJJ. A complex genetic switch involving overlapping divergent promoters and DNA looping regulates expression of conjugation genes of a gram-positive plasmid. PLoS Genet 2014; 10:e1004733. [PMID: 25340403 PMCID: PMC4207663 DOI: 10.1371/journal.pgen.1004733] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 09/03/2014] [Indexed: 11/22/2022] Open
Abstract
Plasmid conjugation plays a significant role in the dissemination of antibiotic resistance and pathogenicity determinants. Understanding how conjugation is regulated is important to gain insights into these features. Little is known about regulation of conjugation systems present on plasmids from Gram-positive bacteria. pLS20 is a native conjugative plasmid from the Gram-positive bacterium Bacillus subtilis. Recently the key players that repress and activate pLS20 conjugation have been identified. Here we studied in detail the molecular mechanism regulating the pLS20 conjugation genes using both in vivo and in vitro approaches. Our results show that conjugation is subject to the control of a complex genetic switch where at least three levels of regulation are integrated. The first of the three layers involves overlapping divergent promoters of different strengths regulating expression of the conjugation genes and the key transcriptional regulator RcoLS20. The second layer involves a triple function of RcoLS20 being a repressor of the main conjugation promoter and an activator and repressor of its own promoter at low and high concentrations, respectively. The third level of regulation concerns formation of a DNA loop mediated by simultaneous binding of tetrameric RcoLS20 to two operators, one of which overlaps with the divergent promoters. The combination of these three layers of regulation in the same switch allows the main conjugation promoter to be tightly repressed during conditions unfavorable to conjugation while maintaining the sensitivity to accurately switch on the conjugation genes when appropriate conditions occur. The implications of the regulatory switch and comparison with other genetic switches involving DNA looping are discussed. Plasmids are extrachromosomal, autonomously replicating units that are harbored by many bacteria. Many plasmids encode transfer function allowing them to be transferred into plasmid-free bacteria by a process named conjugation. Since many of them also carry antibiotic resistance genes, plasmid-mediated conjugation is a major mechanism in the dissemination of antibiotic resistance. In depth knowledge on the regulation of conjugation genes is a prerequisite to design measures interfering with the spread of antibiotic resistance. pLS20 is a conjugative plasmid of the soil bacterium Bacillus subtilis, which is also a gut commensal in animals and humans. Here we describe in detail the molecular mechanism by which the key transcriptional regulator tightly represses the conjugation genes during conditions unfavorable to conjugation without compromising the ability to switch on accurately the conjugation genes when appropriate. We found that conjugation is subject to the control of a unique genetic switch where at least three levels of regulation are integrated. The first level involves overlapping divergent promoters of different strengths. The second layer involves a triple function of the transcriptional regulator. And the third level of regulation concerns formation of a DNA loop mediated by the transcriptional regulator.
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Affiliation(s)
- Gayetri Ramachandran
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Instituto de Biología Molecular “Eladio Viñuela” (CSIC), Universidad Autónoma, Canto Blanco, Madrid, Spain
| | - Praveen K. Singh
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Instituto de Biología Molecular “Eladio Viñuela” (CSIC), Universidad Autónoma, Canto Blanco, Madrid, Spain
| | | | - Luis Yuste
- Centro Nacional de Biotecnología (CSIC), Canto Blanco, Madrid, Spain
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas (CSIC), Madrid, Spain
| | - Fernando Rojo
- Centro Nacional de Biotecnología (CSIC), Canto Blanco, Madrid, Spain
| | - Ling J. Wu
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Wilfried J. J. Meijer
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM), Instituto de Biología Molecular “Eladio Viñuela” (CSIC), Universidad Autónoma, Canto Blanco, Madrid, Spain
- * E-mail:
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Robb ML, Shahrezaei V. Stochastic cellular fate decision making by multiple infecting lambda phage. PLoS One 2014; 9:e103636. [PMID: 25105971 PMCID: PMC4126663 DOI: 10.1371/journal.pone.0103636] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/29/2014] [Indexed: 11/19/2022] Open
Abstract
Bacteriophage lambda is a classic system for the study of cellular decision making. Both experiments and mathematical models have demonstrated the importance of viral concentration in the lysis-lysogeny decision outcome in lambda phage. However, a recent experimental study using single cell and single phage resolution reported that cells with the same viral concentrations but different numbers of infecting phage (multiplicity of infection) can have markedly different rates of lysogeny. Thus the decision depends on not only viral concentration, but also directly on the number of infecting phage. Here, we attempt to provide a mechanistic explanation of these results using a simple stochastic model of the lambda phage genetic network. Several potential factors including intrinsic gene expression noise, spatial dynamics and cell-cycle effects are investigated. We find that interplay between the level of intrinsic noise and viral protein decision threshold is a major factor that produces dependence on multiplicity of infection. However, simulations suggest spatial segregation of phage particles does not play a significant role. Cellular image processing is used to re-analyse the original time-lapse movies from the recent study and it is found that higher numbers of infecting phage reduce the cell elongation rate. This could also contribute to the observed phenomena as cellular growth rate can affect transcription rates. Our model further predicts that rate of lysogeny is dependent on bacterial growth rate, which can be experimentally tested. Our study provides new insight on the mechanisms of individual phage decision making. More generally, our results are relevant for the understanding of gene-dosage compensation in cellular systems.
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Affiliation(s)
- Matthew L. Robb
- Department of Mathematics, Imperial College, London, United Kingdom
| | - Vahid Shahrezaei
- Department of Mathematics, Imperial College, London, United Kingdom
- * E-mail:
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Rosano GL, Ceccarelli EA. Recombinant protein expression in Escherichia coli: advances and challenges. Front Microbiol 2014; 5:172. [PMID: 24860555 PMCID: PMC4029002 DOI: 10.3389/fmicb.2014.00172] [Citation(s) in RCA: 1299] [Impact Index Per Article: 129.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/29/2014] [Indexed: 12/28/2022] Open
Abstract
Escherichia coli is one of the organisms of choice for the production of recombinant proteins. Its use as a cell factory is well-established and it has become the most popular expression platform. For this reason, there are many molecular tools and protocols at hand for the high-level production of heterologous proteins, such as a vast catalog of expression plasmids, a great number of engineered strains and many cultivation strategies. We review the different approaches for the synthesis of recombinant proteins in E. coli and discuss recent progress in this ever-growing field.
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Affiliation(s)
- Germán L Rosano
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas Rosario, Argentina ; Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Rosario, Argentina
| | - Eduardo A Ceccarelli
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas Rosario, Argentina ; Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Rosario, Argentina
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41
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Bondy-Denomy J, Davidson AR. When a virus is not a parasite: the beneficial effects of prophages on bacterial fitness. J Microbiol 2014; 52:235-42. [PMID: 24585054 DOI: 10.1007/s12275-014-4083-3] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 02/10/2014] [Indexed: 12/25/2022]
Abstract
Most organisms on the planet have viruses that infect them. Viral infection may lead to cell death, or to a symbiotic relationship where the genomes of both virus and host replicate together. In the symbiotic state, both virus and cell potentially experience increased fitness as a result of the other. The viruses that infect bacteria, called bacteriophages (or phages), well exemplify the symbiotic relationships that can develop between viruses and their host. In this review, we will discuss the many ways that prophages, which are phage genomes integrated into the genomes of their hosts, influence bacterial behavior and virulence.
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Affiliation(s)
- Joseph Bondy-Denomy
- Departments of Molecular Genetics and Biochemistry, University of Toronto, Toronto, Ontario, Canada
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42
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Molecular biology of fuselloviruses and their satellites. Extremophiles 2014; 18:473-89. [DOI: 10.1007/s00792-014-0634-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 01/31/2014] [Indexed: 10/25/2022]
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43
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The δ subunit of RNA polymerase guides promoter selectivity and virulence in Staphylococcus aureus. Infect Immun 2014; 82:1424-35. [PMID: 24491578 DOI: 10.1128/iai.01508-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In Gram-positive bacteria, and particularly the Firmicutes, the DNA-dependent RNA polymerase (RNAP) complex contains an additional subunit, termed the δ factor, or RpoE. This enigmatic protein has been studied for more than 30 years for various organisms, but its function is still not well understood. In this study, we investigated its role in the major human pathogen Staphylococcus aureus. We showed conservation of important structural regions of RpoE in S. aureus and other species and demonstrated binding to core RNAP that is mediated by the β and/or β' subunits. To identify the impact of the δ subunit on transcription, we performed transcriptome sequencing (RNA-seq) analysis and observed 191 differentially expressed genes in the rpoE mutant. Ontological analysis revealed, quite strikingly, that many of the downregulated genes were known virulence factors, while several mobile genetic elements (SaPI5 and prophage SA3usa) were strongly upregulated. Phenotypically, the rpoE mutant had decreased accumulation and/or activity of a number of key virulence factors, including alpha toxin, secreted proteases, and Panton-Valentine leukocidin (PVL). We further observed significantly decreased survival of the mutant in whole human blood, increased phagocytosis by human leukocytes, and impaired virulence in a murine model of infection. Collectively, our results demonstrate that the δ subunit of RNAP is a critical component of the S. aureus transcription machinery and plays an important role during infection.
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Bragg R, van der Westhuizen W, Lee JY, Coetsee E, Boucher C. Bacteriophages as potential treatment option for antibiotic resistant bacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 807:97-110. [PMID: 24619620 DOI: 10.1007/978-81-322-1777-0_7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The world is facing an ever-increasing problem with antibiotic resistant bacteria and we are rapidly heading for a post-antibiotic era. There is an urgent need to investigate alterative treatment options while there are still a few antibiotics left. Bacteriophages are viruses that specifically target bacteria. Before the development of antibiotics, some efforts were made to use bacteriophages as a treatment option, but most of this research stopped soon after the discovery of antibiotics. There are two different replication options which bacteriophages employ. These are the lytic and lysogenic life cycles. Both these life cycles have potential as treatment options. There are various advantages and disadvantages to the use of bacteriophages as treatment options. The main advantage is the specificity of bacteriophages and treatments can be designed to specifically target pathogenic bacteria while not negatively affecting the normal microbiota. There are various advantages to this. However, the high level of specificity also creates potential problems, the main being the requirement of highly specific diagnostic procedures. Another potential problem with phage therapy includes the development of immunity and limitations with the registration of phage therapy options. The latter is driving research toward the expression of phage genes which break the bacterial cell wall, which could then be used as a treatment option. Various aspects of phage therapy have been investigated in studies undertaken by our research group. We have investigated specificity of phages to various avian pathogenic E. coli isolates. Furthermore, the exciting NanoSAM technology has been employed to investigate bacteriophage replication and aspects of this will be discussed.
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Affiliation(s)
- Robert Bragg
- Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 399, Bloemfontein, 9300, South Africa,
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45
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Xia Y, DiPrimio N, Keppel TR, Vo B, Fraser K, Battaile KP, Egan C, Bystroff C, Lovell S, Weis DD, Anderson JC, Karanicolas J. The designability of protein switches by chemical rescue of structure: mechanisms of inactivation and reactivation. J Am Chem Soc 2013; 135:18840-9. [PMID: 24313858 DOI: 10.1021/ja407644b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The ability to selectively activate function of particular proteins via pharmacological agents is a longstanding goal in chemical biology. Recently, we reported an approach for designing a de novo allosteric effector site directly into the catalytic domain of an enzyme. This approach is distinct from traditional chemical rescue of enzymes in that it relies on disruption and restoration of structure, rather than active site chemistry, as a means to achieve modulate function. However, rationally identifying analogous de novo binding sites in other enzymes represents a key challenge for extending this approach to introduce allosteric control into other enzymes. Here we show that mutation sites leading to protein inactivation via tryptophan-to-glycine substitution and allowing (partial) reactivation by the subsequent addition of indole are remarkably frequent. Through a suite of methods including a cell-based reporter assay, computational structure prediction and energetic analysis, fluorescence studies, enzymology, pulse proteolysis, X-ray crystallography, and hydrogen-deuterium mass spectrometry, we find that these switchable proteins are most commonly modulated indirectly, through control of protein stability. Addition of indole in these cases rescues activity not by reverting a discrete conformational change, as we had observed in the sole previously reported example, but rather rescues activity by restoring protein stability. This important finding will dramatically impact the design of future switches and sensors built by this approach, since evaluating stability differences associated with cavity-forming mutations is a far more tractable task than predicting allosteric conformational changes. By analogy to natural signaling systems, the insights from this study further raise the exciting prospect of modulating stability to design optimal recognition properties into future de novo switches and sensors built through chemical rescue of structure.
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Affiliation(s)
- Yan Xia
- Department of Molecular Biosciences, ‡Department of Chemistry, §Protein Structure Laboratory, and ∥Center for Bioinformatics, University of Kansas , Lawrence, Kansas 66045, United States
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Broussard GW, Oldfield LM, Villanueva VM, Lunt BL, Shine EE, Hatfull GF. Integration-dependent bacteriophage immunity provides insights into the evolution of genetic switches. Mol Cell 2012; 49:237-48. [PMID: 23246436 DOI: 10.1016/j.molcel.2012.11.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/05/2012] [Accepted: 11/07/2012] [Indexed: 02/06/2023]
Abstract
Genetic switches are critical components of developmental circuits. Because temperate bacteriophages are vastly abundant and greatly diverse, they are rich resources for understanding the mechanisms and evolution of switches and the molecular control of genetic circuitry. Here, we describe a new class of small, compact, and simple switches that use site-specific recombination as the key decision point. The phage attachment site attP is located within the phage repressor gene such that chromosomal integration results in removal of a C-terminal tag that destabilizes the virally encoded form of the repressor. Integration thus not only confers prophage stability but also is a requirement for lysogenic establishment. The variety of these self-contained integration-dependent immunity systems in different genomic contexts suggests that these represent ancestral states in switch evolution from which more-complex switches have evolved. They also provide a powerful toolkit for building synthetic biological circuits.
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Affiliation(s)
- Gregory W Broussard
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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47
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Bochow S, Elliman J, Owens L. Bacteriophage adenine methyltransferase: a life cycle regulator? Modelled usingVibrio harveyimyovirus like. J Appl Microbiol 2012; 113:1001-13. [DOI: 10.1111/j.1365-2672.2012.05358.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/27/2012] [Accepted: 05/28/2012] [Indexed: 12/11/2022]
Affiliation(s)
- S. Bochow
- Microbiology and Immunology; James Cook University; Townsville; Qld; Australia
| | - J. Elliman
- Microbiology and Immunology; James Cook University; Townsville; Qld; Australia
| | - L. Owens
- Microbiology and Immunology; James Cook University; Townsville; Qld; Australia
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SUBILS TOMÁS, AQUILI VIRGINIA, EBNER GUILLERMO, BALAGUÉ CLAUDIA. Effect of Preservatives on Shiga Toxigenic Phages and Shiga Toxin of Escherichia coli O157:H7. J Food Prot 2012; 75:959-65. [DOI: 10.4315/0362-028x.jfp-11-332] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Toxin synthesis by Shiga toxin–producing Escherichia coli (STEC) appears to be coregulated through the induction of the integrated bacteriophages that encode the toxin genes. These phages might be the principal means for the dissemination and release of Shiga toxins. We evaluated the effect of three common food preservatives, potassium sorbate, sodium benzoate, and sodium propionate, on the propagation of the phages and Shiga toxins. We tested each preservative at four concentrations, 1, 1.25, 2.5, and 5 mg/ml, both on free phages and on lysogenic phages in bacteria. We also evaluated the expression of a lambdoid phage, which was exposed to increasing concentrations of preservatives, by measuring β-galactosidase activity from SPC105, a transductant strain. Furthermore, we tested the effect of the preservatives on cytotoxigenic activity of Shiga toxin on Vero cells. We detected an increase of the inhibitory effect of the phage lytic activity, both in lysogenic and free phages, as the preservative concentration increased. However, the inhibition was higher on the lysogenic phages release than on free phages. Sodium benzoate and potassium sorbate were about equal at inhibiting phages; they were more effective than sodium propionate. A significant decrease of lacZ expression, encoded in a lambda phage, was observed. We also found a reduction in Shiga toxin titer caused by exposure of E. coli O157:H7 to 5 mg/ml sodium benzoate or potassium sorbate. These results imply that these three preservatives, used to inhibit microbial spoilage of foods, also act to inhibit lytic activity and dispersion of a phage carrying the gene encoding powerful Shiga cytotoxins. Also notable was the inactivation of Shiga toxin activity, although this effect was detected using concentrations of preservatives greater than those allowed by the Argentine Food Code.
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Affiliation(s)
- TOMÁS SUBILS
- Área Bacteriología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531 S2002LRK, Rosario, Santa Fe, Argentina
| | - VIRGINIA AQUILI
- Área Bacteriología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531 S2002LRK, Rosario, Santa Fe, Argentina
| | - GUILLERMO EBNER
- Área Bacteriología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531 S2002LRK, Rosario, Santa Fe, Argentina
| | - CLAUDIA BALAGUÉ
- Área Bacteriología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531 S2002LRK, Rosario, Santa Fe, Argentina
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49
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Abstract
Transcription factors mediate the formation of nucleoprotein complexes that are critical for efficient regulation of epigenetic switches. In these complexes, DNA is frequently bent or looped by the protein; other times, strong interactions lead the DNA to fully wrap the regulatory protein(s). The equilibrium between the bending, looping, full and partial wrapping of DNA governs the level of transcriptional regulation and is tuned by biophysical parameters. Characterization of the structure, kinetics, and thermodynamics of formation of such nucleoprotein complexes is fundamental to the understanding of the molecular mechanisms that underlie the operation of the genetic switches controlled by them. Here, we describe in detail how to perform tethered particle motion experiments aimed at understanding how protein-DNA interactions influence the formation and breakdown of these regulatory complexes.
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Abstract
Bacteriophage λ, rediscovered in the early 1950s, has served as a model in molecular biology studies for decades. Although currently more complex organisms and more complicated biological systems can be studied, this phage is still an excellent model to investigate principles of biological processes occurring at the molecular level. In fact, very few other biological models provide possibilities to examine regulations of biological mechanisms as detailed as performed with λ. In this chapter, recent advances in our understanding of mechanisms of bacteriophage λ development are summarized and discussed. Particularly, studies on (i) phage DNA injection, (ii) molecular bases of the lysis-versus-lysogenization decision and the lysogenization process itself, (iii) prophage maintenance and induction, (iv), λ DNA replication, (v) phage-encoded recombination systems, (vi) transcription antitermination, (vii) formation of the virion structure, and (viii) lysis of the host cell, as published during several past years, will be presented.
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