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Little JI, Singh PK, Zhao J, Dunn S, Matz H, Donnenberg MS. Type IV pili of Enterobacteriaceae species. EcoSal Plus 2024:eesp00032023. [PMID: 38294234 DOI: 10.1128/ecosalplus.esp-0003-2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 12/01/2023] [Indexed: 02/01/2024]
Abstract
Type IV pili (T4Ps) are surface filaments widely distributed among bacteria and archaea. T4Ps are involved in many cellular functions and contribute to virulence in some species of bacteria. Due to the diversity of T4Ps, different properties have been observed for homologous proteins that make up T4Ps in various organisms. In this review, we highlight the essential components of T4Ps, their functions, and similarities to related systems. We emphasize the unique T4Ps of enteric pathogens within the Enterobacteriaceae family, which includes pathogenic strains of Escherichia coli and Salmonella. These include the bundle-forming pilus (BFP) of enteropathogenic E. coli (EPEC), longus (Lng) and colonization factor III (CFA/III) of enterotoxigenic E. coli (ETEC), T4P of Salmonella enterica serovar Typhi, Colonization Factor Citrobacter (CFC) of Citrobacter rodentium, T4P of Yersinia pseudotuberculosis, a ubiquitous T4P that was characterized in enterohemorrhagic E. coli (EHEC), and the R64 plasmid thin pilus. Finally, we highlight areas for further study.
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Affiliation(s)
- Janay I Little
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Pradip K Singh
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Jinlei Zhao
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Shakeera Dunn
- Internal Medicine Residency, Bayhealth Medical Center, Dover, Delaware, USA
| | - Hanover Matz
- Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
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2
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Jia Q, Xiang Y. Cryo-EM structure of a bacteriophage M13 mini variant. Nat Commun 2023; 14:5421. [PMID: 37669979 PMCID: PMC10480500 DOI: 10.1038/s41467-023-41151-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/24/2023] [Indexed: 09/07/2023] Open
Abstract
Filamentous bacteriophages package their circular, single stranded DNA genome with the major coat protein pVIII and the minor coat proteins pIII, pVII, pVI, and pIX. Here, we report the cryo-EM structure of a ~500 Å long bacteriophage M13 mini variant. The distal ends of the mini phage are sealed by two cap-like complexes composed of the minor coat proteins. The top cap complex consists of pVII and pIX, both exhibiting a single helix structure. Arg33 of pVII and Glu29 of pIX, located on the inner surface of the cap, play a key role in recognizing the genome packaging signal. The bottom cap complex is formed by the hook-like structures of pIII and pVI, arranged in helix barrels. Most of the inner ssDNA genome adopts a double helix structure with a similar pitch to that of the A-form double-stranded DNA. These findings provide insights into the assembly of filamentous bacteriophages.
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Affiliation(s)
- Qi Jia
- Beijing Frontier Research Center for Biological Structure, Center for Infectious Disease Research, SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, P.R. China
| | - Ye Xiang
- Beijing Frontier Research Center for Biological Structure, Center for Infectious Disease Research, SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, P.R. China.
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3
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Billaud M, Petit MA, Lossouarn J. The Clostridium-infecting filamentous phage CAK1 genome analysis allows to define a new potential clade of Tubulavirales. FEMS Microbiol Lett 2023; 370:fnad099. [PMID: 37791400 DOI: 10.1093/femsle/fnad099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/21/2023] [Accepted: 10/02/2023] [Indexed: 10/05/2023] Open
Abstract
What we know about Tubulavirales, i.e. filamentous phages, essentially comes from Gram-negative-infecting Inoviridae. However, metagenomics recently suggests filamentous phages are much more widespread and diverse. Here, we report the complete sequence and functional annotation of CAK1, a 6.6 kb filamentous phage that was shown to chronically infect Clostridium beijerinckii 30 years ago and only represents the second filamentous phage cultivated on a Gram-positive bacterium. CAK1 has a typical filamentous phage modular genome with no homologs in databases and we were interested to compare it with a pig gut filamentous phage metagenomics dataset that we previously assembled and for which many filamentous phages were predicted to infect Clostridium species by bioinformatics means. CAK1 is distantly related to nine of these sequences, two of which have been predicted as Clostridium-associated. In itself, this small cluster of CAK1-connected sequences sheds light on the diversity of filamentous phages that putatively infect Clostridium species, and probably many other Gram-positive genera.
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Affiliation(s)
- Maud Billaud
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France
| | - Marie-Agnès Petit
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France
| | - Julien Lossouarn
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350 Jouy-en-Josas, France
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4
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Kim SJ, Lee Y, Choi EJ, Lee JM, Kim KH, Oh JW. The development progress of multi-array colourimetric sensors based on the M13 bacteriophage. NANO CONVERGENCE 2023; 10:1. [PMID: 36595116 PMCID: PMC9808696 DOI: 10.1186/s40580-022-00351-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 12/08/2022] [Indexed: 06/17/2023]
Abstract
Techniques for detecting chemicals dispersed at low concentrations in air continue to evolve. These techniques can be applied not only to manage the quality of agricultural products using a post-ripening process but also to establish a safety prevention system by detecting harmful gases and diagnosing diseases. Recently, techniques for rapid response to various chemicals and detection in complex and noisy environments have been developed using M13 bacteriophage-based sensors. In this review, M13 bacteriophage-based multi-array colourimetric sensors for the development of an electronic nose is discussed. The self-templating process was adapted to fabricate a colour band structure consisting of an M13 bacteriophage. To detect diverse target chemicals, the colour band was utilised with wild and genetically engineered M13 bacteriophages to enhance their sensing abilities. Multi-array colourimetric sensors were optimised for application in complex and noisy environments based on simulation and deep learning analysis. The development of a multi-array colourimetric sensor platform based on the M13 bacteriophage is likely to result in significant advances in the detection of various harmful gases and the diagnosis of various diseases based on exhaled gas in the future.
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Affiliation(s)
- Sung-Jo Kim
- Bio-IT Fusion Technology Research Institute, Pusan National University, Busan, Republic of Korea
| | - Yujin Lee
- Department of Nano Fusion Technology, Pusan National University, Busan, Republic of Korea
| | - Eun Jung Choi
- Bio-IT Fusion Technology Research Institute, Pusan National University, Busan, Republic of Korea
- Korea Nanobiotechnology Center, Pusan National University, Busan, Republic of Korea
| | - Jong-Min Lee
- School of Nano Convergence Technology, Hallym University, Chuncheon, Republic of Korea
- Korea and Nano Convergence Technology Center, Hallym University, Chuncheon, Republic of Korea
| | - Kwang Ho Kim
- School of Materials Science and Engineering, Pusan National University, Busan, Republic of Korea
- Global Frontier Research and Development Center for Hybrid Interface Materials, Pusan National University, Busan, Republic of Korea
| | - Jin-Woo Oh
- Bio-IT Fusion Technology Research Institute, Pusan National University, Busan, Republic of Korea
- Department of Nano Fusion Technology, Pusan National University, Busan, Republic of Korea
- Korea Nanobiotechnology Center, Pusan National University, Busan, Republic of Korea
- Department of Nanoenergy Engineering and Research Center for Energy Convergence Technology, Pusan National University, Busan, Republic of Korea
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5
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Haase M, Tessmer L, Köhnlechner L, Kuhn A. The M13 Phage Assembly Machine Has a Membrane-Spanning Oligomeric Ring Structure. Viruses 2022; 14:v14061163. [PMID: 35746635 PMCID: PMC9228878 DOI: 10.3390/v14061163] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 02/04/2023] Open
Abstract
Bacteriophage M13 assembles its progeny particles in the inner membrane of the host. The major component of the assembly machine is G1p and together with G11p it generates an oligomeric structure with a pore-like inner cavity and an ATP hydrolysing domain. This allows the formation of the phage filament, which assembles multiple copies of the membrane-inserted major coat protein G8p around the extruding single-stranded circular DNA. The phage filament then passes through the G4p secretin that is localized in the outer membrane. Presumably, the inner membrane G1p/G11p and the outer G4p form a common complex. To unravel the structural details of the M13 assembly machine, we purified G1p from infected E. coli cells. The protein was overproduced together with G11p and solubilized from the membrane as a multimeric complex with a size of about 320 kDa. The complex revealed a pore-like structure with an outer diameter of about 12 nm, matching the dimensions of the outer membrane G4p secretin. The function of the M13 assembly machine for phage generation and secretion is discussed.
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6
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Investigation of the Relation between Temperature and M13 Phage Production via ATP Expenditure. Processes (Basel) 2022. [DOI: 10.3390/pr10050962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/10/2022] Open
Abstract
M13 bacteriophage is a promising biomolecule capable of various bionano and material science applications. The biomaterial can self-assemble into matrices to fabricate bioscaffolds using high phage concentration and high phage purity. Previous studies aimed to acquire these conditions in large-scale phage production and have identified the optimal culture temperature range at 28–31 °C. However, explanations as to why this temperature range was optimal for phage production is absent from the work. Therefore, in this study, we identified the relation between culture temperature and M13 phage production using ATP expenditure calculations to comprehend the high yield phage production at the optimal temperature range. We extended a coarse-grained model for the evaluation of phage protein and ribosomal protein synthesis with the premise that phage proteins (a ribosomal protein) are translated by bacterial ribosomes in E. coli through expenditure of ATP energy. By comparing the ATP energy for ribosomal protein synthesis estimated using the coarse-grained model and the experimentally calculated ATP expenditure for phage production, we interpreted the high phage yield at the optimal temperature range and recognized ATP analysis as a reasonable method that can be used to evaluate other parameters for phage production optimization.
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Conners R, McLaren M, Łapińska U, Sanders K, Stone MRL, Blaskovich MAT, Pagliara S, Daum B, Rakonjac J, Gold VAM. CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage. Nat Commun 2021; 12:6316. [PMID: 34728631 PMCID: PMC8563730 DOI: 10.1038/s41467-021-26610-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 11/09/2022] Open
Abstract
The Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we determine the structure of pIV from the f1 filamentous bacteriophage at 2.7 Å resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV subunits assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage egress. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.
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Affiliation(s)
- Rebecca Conners
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Kelly Sanders
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Jasna Rakonjac
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Exeter, UK.
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK.
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Abstract
Members of the family Inoviridae are non-enveloped flexible filamentous bacteriophages (600–2500×6–10 nm) with supercoiled, circular, positive-sense, single-stranded DNA genomes of 5.5–10.6 kb, encoding 7–15 proteins. They absorb to the pili of Gram-negative bacteria and replicate their DNA by a rolling-circle mechanism with progeny released from cells by extrusion without killing the host. Phage DNA can persist extra-chromosomally or integrate into the bacterial genome. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the family Inoviridae, which is available at ictv.global/report/inoviridae.
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Affiliation(s)
- Petar Knezevic
- University of Novi Sad, Faculty of Sciences, Department of Biology and Ecology, Trg Dositeja Obradovica 3, 21000 Novi Sad, Vojvodina, Serbia
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Akremi I, Holtappels D, Brabra W, Jlidi M, Hadj Ibrahim A, Ben Ali M, Fortuna K, Ahmed M, Meerbeek BV, Rhouma A, Lavigne R, Ben Ali M, Wagemans J. First Report of Filamentous Phages Isolated from Tunisian Orchards to Control Erwinia amylovora. Microorganisms 2020; 8:microorganisms8111762. [PMID: 33182526 PMCID: PMC7697814 DOI: 10.3390/microorganisms8111762] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 01/28/2023] Open
Abstract
Newly discovered Erwinia amylovora phages PEar1, PEar2, PEar4 and PEar6 were isolated from three different orchards in North Tunisia to study their potential as biocontrol agents. Illumina sequencing revealed that the PEar viruses carry a single-strand DNA genome between 6608 and 6801 nucleotides and belong to the Inoviridae, making them the first described filamentous phages of E. amylovora. Interestingly, phage-infected cells show a decreased swimming and swarming motility and a cocktail of the four phages can significantly reduce infection of E. amylovora in a pear bioassay, potentially making them suitable candidates for phage biocontrol.
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Affiliation(s)
- Ismahen Akremi
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21-Box 2462, 3001 Leuven, Belgium; (D.H.); (K.F.); (R.L.)
| | - Dominique Holtappels
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21-Box 2462, 3001 Leuven, Belgium; (D.H.); (K.F.); (R.L.)
| | - Wided Brabra
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
- Astrum Biotech, Business Incubator, Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia
| | - Mouna Jlidi
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
| | - Adel Hadj Ibrahim
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
| | - Manel Ben Ali
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
- Astrum Biotech, Business Incubator, Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia
| | - Kiandro Fortuna
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21-Box 2462, 3001 Leuven, Belgium; (D.H.); (K.F.); (R.L.)
| | - Mohammed Ahmed
- Biomaterials Research Group (BIOMAT), Department of Oral Sciences, KU Leuven, Kapucijnenvoer 7-Block A Box 7001, 3000 Leuven, Belgium; (M.A.); (B.V.M.)
- Department of Dental Biomaterials, Tanta University, Biomedical Campus, 32511 Tanta, Gharbia Governorate, Egypt
| | - Bart Van Meerbeek
- Biomaterials Research Group (BIOMAT), Department of Oral Sciences, KU Leuven, Kapucijnenvoer 7-Block A Box 7001, 3000 Leuven, Belgium; (M.A.); (B.V.M.)
| | - Ali Rhouma
- Laboratory of Integrated Olive Production, Olive Tree Institute, BP208 Marhajene City, Tunis 1082, Tunisia;
| | - Rob Lavigne
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21-Box 2462, 3001 Leuven, Belgium; (D.H.); (K.F.); (R.L.)
| | - Mamdouh Ben Ali
- Laboratory of Microbial Biotechnology, Enzymatics and Biomolecules (LBMEB), Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia; (I.A.); (W.B.); (M.J.); (A.H.I.); (M.B.A.); (M.B.A.)
- Astrum Biotech, Business Incubator, Center of Biotechnology of Sfax (CBS), University of Sfax, Road of Sidi Mansour km 6, P.O. Box 1177, Sfax 3018, Tunisia
| | - Jeroen Wagemans
- Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21-Box 2462, 3001 Leuven, Belgium; (D.H.); (K.F.); (R.L.)
- Correspondence: ; Tel.: +32-1637-4622
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Bashir S, Paeshuyse J. Construction of Antibody Phage Libraries and Their Application in Veterinary Immunovirology. Antibodies (Basel) 2020; 9:E21. [PMID: 32503103 PMCID: PMC7345743 DOI: 10.3390/antib9020021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/26/2020] [Accepted: 04/28/2020] [Indexed: 12/14/2022] Open
Abstract
Antibody phage display (APD) technology has revolutionized the field of immunovirology with its application in viral disease diagnostics and antiviral therapy. This robust and versatile technology allows the expression of an antibody fused to a phage coat protein on the surface of a filamentous phage. The DNA sequence coding for the antibody is packaged within the phage, linking the phenotype to genotype. Antibody phage display inherits the ability to rapidly generate and modify or improve high-affinity monoclonal antibodies, rendering it indispensable in immunology. In the last two decades, phage-display-derived antibodies have been extensively used in human medicine as diagnostic and therapeutic modalities. Recently, they are also gaining significant ground in veterinary medicine. Even though these advancements are mainly biased towards economically important animals such as chicken, cattle, and pigs, they are laying the foundation of fulfilling the unmet needs of veterinary medicine as antibody-based biologics in viral diagnostics, therapeutics, and immunoprophylaxis. This review provides a brief overview of the construction of antibody phage libraries and their application in diagnosis, prevention, and control of infectious viral diseases in veterinary medicine in detail.
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Affiliation(s)
| | - Jan Paeshuyse
- Department of Biosystems, Division of Animal and Human Health Engineering, Laboratory of Host Pathogen Interaction in Livestock, KU Leuven University, 3000 Leuven, Belgium;
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Hay ID, Lithgow T. Filamentous phages: masters of a microbial sharing economy. EMBO Rep 2019; 20:e47427. [PMID: 30952693 PMCID: PMC6549030 DOI: 10.15252/embr.201847427] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/30/2019] [Accepted: 03/19/2019] [Indexed: 12/11/2022] Open
Abstract
Bacteriophage ("bacteria eaters") or phage is the collective term for viruses that infect bacteria. While most phages are pathogens that kill their bacterial hosts, the filamentous phages of the sub-class Inoviridae live in cooperative relationships with their bacterial hosts, akin to the principal behaviours found in the modern-day sharing economy: peer-to-peer support, to offset any burden. Filamentous phages impose very little burden on bacteria and offset this by providing service to help build better biofilms, or provision of toxins and other factors that increase virulence, or modified behaviours that provide novel motile activity to their bacterial hosts. Past, present and future biotechnology applications have been built on this phage-host cooperativity, including DNA sequencing technology, tools for genetic engineering and molecular analysis of gene expression and protein production, and phage-display technologies for screening protein-ligand and protein-protein interactions. With the explosion of genome and metagenome sequencing surveys around the world, we are coming to realize that our knowledge of filamentous phage diversity remains at a tip-of-the-iceberg stage, promising that new biology and biotechnology are soon to come.
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Affiliation(s)
- Iain D Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Trevor Lithgow
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Vic., Australia
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12
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Loh B, Kuhn A, Leptihn S. The fascinating biology behind phage display: filamentous phage assembly. Mol Microbiol 2019; 111:1132-1138. [PMID: 30556628 DOI: 10.1111/mmi.14187] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
With the recently awarded Nobel Prize to the inventor of Phage Display, George Smith, the technique has once more gained attention. However, one should not forget about the biology behind the method. Almost always ignored is how the structure of this bacterial virus is assembled. In contrast to lytic phages, filamentous phages are constantly being extruded through the bacterial membranes without lysis. Such filamentous phages are found in all aquatic environments, such as rivers and lakes, in the deep sea, in arctic ice, in hot springs and, associated with their hosts, in plants and animals including humans. While most filamentous phages infect Gram-negative hosts, inoviruses of Gram-positive hosts have also been described. Despite being among the minority within the phage family with an estimate of less than 5%, filamentous phages are real parasites as they exist at the expense of the host, but do not kill it. In contrast to lytic bacteriophages, filamentous phages are assembled in the host's membrane and extruded across the cellular envelope while the bacterium continues to grow. In this review, we focus on this complex and yet poorly understood process of assembly and secretion of filamentous phages.
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Affiliation(s)
- Belinda Loh
- Zhejiang University School of Medicine, Zhejiang University-Edinburgh University (ZJU-UoE) Institute, International Campus, Zhejiang University, 718 East Haizhou Road, Haining, Zhejiang, 314400, P.R. China
| | - Andreas Kuhn
- Institute of Microbiology, University of Hohenheim, Garbenstrasse 30, Stuttgart, 70599, Germany
| | - Sebastian Leptihn
- Zhejiang University School of Medicine, Zhejiang University-Edinburgh University (ZJU-UoE) Institute, International Campus, Zhejiang University, 718 East Haizhou Road, Haining, Zhejiang, 314400, P.R. China
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13
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Margalef-Català M, Stefanelli E, Araque I, Wagner K, Felis GE, Bordons A, Torriani S, Reguant C. Variability in gene content and expression of the thioredoxin system in Oenococcus oeni. Food Microbiol 2017; 61:23-32. [DOI: 10.1016/j.fm.2016.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 06/29/2016] [Accepted: 08/19/2016] [Indexed: 11/17/2022]
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14
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Simulation of the M13 life cycle I: Assembly of a genetically-structured deterministic chemical kinetic simulation. Virology 2016; 500:259-274. [PMID: 27644585 DOI: 10.1016/j.virol.2016.08.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/16/2016] [Accepted: 08/18/2016] [Indexed: 11/22/2022]
Abstract
To expand the quantitative, systems level understanding and foster the expansion of the biotechnological applications of the filamentous bacteriophage M13, we have unified the accumulated quantitative information on M13 biology into a genetically-structured, experimentally-based computational simulation of the entire phage life cycle. The deterministic chemical kinetic simulation explicitly includes the molecular details of DNA replication, mRNA transcription, protein translation and particle assembly, as well as the competing protein-protein and protein-nucleic acid interactions that control the timing and extent of phage production. The simulation reproduces the holistic behavior of M13, closely matching experimentally reported values of the intracellular levels of phage species and the timing of events in the M13 life cycle. The computational model provides a quantitative description of phage biology, highlights gaps in the present understanding of M13, and offers a framework for exploring alternative mechanisms of regulation in the context of the complete M13 life cycle.
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15
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Sattar S, Bennett NJ, Wen WX, Guthrie JM, Blackwell LF, Conway JF, Rakonjac J. Ff-nano, short functionalized nanorods derived from Ff (f1, fd, or M13) filamentous bacteriophage. Front Microbiol 2015; 6:316. [PMID: 25941520 PMCID: PMC4403547 DOI: 10.3389/fmicb.2015.00316] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 03/30/2015] [Indexed: 11/22/2022] Open
Abstract
F-specific filamentous phage of Escherichia coli (Ff: f1, M13, or fd) are long thin filaments (860 nm × 6 nm). They have been a major workhorse in display technologies and bionanotechnology; however, some applications are limited by the high length-to-diameter ratio of Ff. Furthermore, use of functionalized Ff outside of laboratory containment is in part hampered by the fact that they are genetically modified viruses. We have now developed a system for production and purification of very short functionalized Ff-phage-derived nanorods, named Ff-nano, that are only 50 nm in length. In contrast to standard Ff-derived vectors that replicate in E. coli and contain antibiotic-resistance genes, Ff-nano are protein-DNA complexes that cannot replicate on their own and do not contain any coding sequences. These nanorods show an increased resistance to heating at 70∘C in 1% SDS in comparison to the full-length Ff phage of the same coat composition. We demonstrate that functionalized Ff-nano particles are suitable for application as detection particles in sensitive and quantitative “dipstick” lateral flow diagnostic assay for human plasma fibronectin.
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Affiliation(s)
- Sadia Sattar
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand
| | - Nicholas J Bennett
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand
| | - Wesley X Wen
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand
| | - Jenness M Guthrie
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand ; Science Haven Limited, Palmerston North New Zealand
| | - Len F Blackwell
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand ; Science Haven Limited, Palmerston North New Zealand
| | - James F Conway
- University of Pittsburgh School of Medicine Pittsburgh, PA, USA
| | - Jasna Rakonjac
- Institute of Fundamental Sciences, Massey University Palmerston North, New Zealand
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16
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Mai-Prochnow A, Hui JGK, Kjelleberg S, Rakonjac J, McDougald D, Rice SA. 'Big things in small packages: the genetics of filamentous phage and effects on fitness of their host'. FEMS Microbiol Rev 2015; 39:465-87. [PMID: 25670735 DOI: 10.1093/femsre/fuu007] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 12/17/2014] [Indexed: 01/01/2023] Open
Abstract
This review synthesizes recent and past observations on filamentous phages and describes how these phages contribute to host phentoypes. For example, the CTXφ phage of Vibrio cholerae encodes the cholera toxin genes, responsible for causing the epidemic disease, cholera. The CTXφ phage can transduce non-toxigenic strains, converting them into toxigenic strains, contributing to the emergence of new pathogenic strains. Other effects of filamentous phage include horizontal gene transfer, biofilm development, motility, metal resistance and the formation of host morphotypic variants, important for the biofilm stress resistance. These phages infect a wide range of Gram-negative bacteria, including deep-sea, pressure-adapted bacteria. Many filamentous phages integrate into the host genome as prophage. In some cases, filamentous phages encode their own integrase genes to facilitate this process, while others rely on host-encoded genes. These differences are mediated by different sets of 'core' and 'accessory' genes, with the latter group accounting for some of the mechanisms that alter the host behaviours in unique ways. It is increasingly clear that despite their relatively small genomes, these phages exert signficant influence on their hosts and ultimately alter the fitness and other behaviours of their hosts.
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Affiliation(s)
- Anne Mai-Prochnow
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia
| | - Janice Gee Kay Hui
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia
| | - Staffan Kjelleberg
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Jasna Rakonjac
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Diane McDougald
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
| | - Scott A Rice
- The Centre for Marine Bio-Innovation and the School of Biotechnology and Biomolecular Sciences, the University of New South Wales, Sydney NSW 2052, Australia The Singapore Centre on Environmental Life Sciences Engineering and the School of Biological Sciences, Nanyang Technological University, 637551, Singapore
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17
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A Single Amino Acid Substitution Changes the Self-Assembly Status of a Type IV Piliation Secretin. J Bacteriol 2012; 194:4951-8. [PMID: 22773793 DOI: 10.1128/jb.00798-12] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Secretins form large multimeric complexes in the outer membranes of many Gram-negative bacteria, where they function as dedicated gateways that allow proteins to access the extracellular environment. Despite their overall relatedness, different secretins use different specific and general mechanisms for their targeting, assembly, and membrane insertion. We report that all tested secretins from several type II secretion systems and from the filamentous bacteriophage f1 can spontaneously multimerize and insert into liposomes in an in vitro transcription-translation system. Phylogenetic analyses indicate that these secretins form a group distinct from the secretins of the type IV piliation and type III secretion systems, which do not autoassemble in vitro. A mutation causing a proline-to-leucine substitution allowed PilQ secretins from two different type IV piliation systems to assemble in vitro, albeit with very low efficiency, suggesting that autoassembly is an inherent property of all secretins.
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18
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Koo J, Burrows LL, Lynne Howell P. Decoding the roles of pilotins and accessory proteins in secretin escort services. FEMS Microbiol Lett 2011; 328:1-12. [DOI: 10.1111/j.1574-6968.2011.02464.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 10/28/2011] [Accepted: 11/11/2011] [Indexed: 12/19/2022] Open
Affiliation(s)
| | - Lori L. Burrows
- Department of Biochemistry and Biomedical Sciences; McMaster University; Hamilton; ON; Canada
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19
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Bennett NJ, Gagic D, Sutherland-Smith AJ, Rakonjac J. Characterization of a Dual-Function Domain That Mediates Membrane Insertion and Excision of Ff Filamentous Bacteriophage. J Mol Biol 2011; 411:972-85. [DOI: 10.1016/j.jmb.2011.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 06/24/2011] [Accepted: 07/01/2011] [Indexed: 10/18/2022]
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20
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Joly N, Engl C, Jovanovic G, Huvet M, Toni T, Sheng X, Stumpf MPH, Buck M. Managing membrane stress: the phage shock protein (Psp) response, from molecular mechanisms to physiology. FEMS Microbiol Rev 2010; 34:797-827. [PMID: 20636484 DOI: 10.1111/j.1574-6976.2010.00240.x] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The bacterial phage shock protein (Psp) response functions to help cells manage the impacts of agents impairing cell membrane function. The system has relevance to biotechnology and to medicine. Originally discovered in Escherichia coli, Psp proteins and homologues are found in Gram-positive and Gram-negative bacteria, in archaea and in plants. Study of the E. coli and Yersinia enterocolitica Psp systems provides insights into how membrane-associated sensory Psp proteins might perceive membrane stress, signal to the transcription apparatus and use an ATP-hydrolysing transcription activator to produce effector proteins to overcome the stress. Progress in understanding the mechanism of signal transduction by the membrane-bound Psp proteins, regulation of the psp gene-specific transcription activator and the cell biology of the system is presented and discussed. Many features of the action of the Psp system appear to be dominated by states of self-association of the master effector, PspA, and the transcription activator, PspF, alongside a signalling pathway that displays strong conditionality in its requirement.
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Affiliation(s)
- Nicolas Joly
- Division of Biology, Imperial College London, South Kensington, London, UK
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21
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Spagnuolo J, Opalka N, Wen WX, Gagic D, Chabaud E, Bellini P, Bennett MD, Norris GE, Darst SA, Russel M, Rakonjac J. Identification of the gate regions in the primary structure of the secretin pIV. Mol Microbiol 2010; 76:133-50. [DOI: 10.1111/j.1365-2958.2010.07085.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Merzlyak A, Lee SW. Engineering Phage Materials with Desired Peptide Display: Rational Design Sustained through Natural Selection. Bioconjug Chem 2009; 20:2300-10. [DOI: 10.1021/bc900303f] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Anna Merzlyak
- UCSF and UC Berkeley Joint Graduate Group in Bioengineering, Berkeley, California 94720, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Department of Bioengineering, University of California, Berkeley, California 94720, and Berkeley Nanoscience and Nanoengineering Institute, Berkeley, California 94720
| | - Seung-Wuk Lee
- UCSF and UC Berkeley Joint Graduate Group in Bioengineering, Berkeley, California 94720, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, Department of Bioengineering, University of California, Berkeley, California 94720, and Berkeley Nanoscience and Nanoengineering Institute, Berkeley, California 94720
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23
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Clock SA, Planet PJ, Perez BA, Figurski DH. Outer membrane components of the Tad (tight adherence) secreton of Aggregatibacter actinomycetemcomitans. J Bacteriol 2008; 190:980-90. [PMID: 18055598 PMCID: PMC2223556 DOI: 10.1128/jb.01347-07] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2007] [Accepted: 11/20/2007] [Indexed: 12/15/2022] Open
Abstract
Prokaryotic secretion relies on proteins that are widely conserved, including NTPases and secretins, and on proteins that are system specific. The Tad secretion system in Aggregatibacter actinomycetemcomitans is dedicated to the assembly and export of Flp pili, which are needed for tight adherence. Consistent with predictions that RcpA forms the multimeric outer membrane secretion channel (secretin) of the Flp pilus biogenesis apparatus, we observed the RcpA protein in multimers that were stable in the presence of detergent and found that rcpA and its closely related homologs form a novel and distinct subfamily within a well-supported gene phylogeny of the entire secretin gene superfamily. We also found that rcpA-like genes were always linked to Aggregatibacter rcpB- or Caulobacter cpaD-like genes. Using antisera, we determined the localization and gross abundances of conserved (RcpA and TadC) and unique (RcpB, RcpC, and TadD) Tad proteins. The three Rcp proteins (RcpA, RcpB, and RcpC) and TadD, a putative lipoprotein, localized to the bacterial outer membrane. RcpA, RcpC, and TadD were also found in the inner membrane, while TadC localized exclusively to the inner membrane. The RcpA secretin was necessary for wild-type abundances of RcpB and RcpC, and TadC was required for normal levels of all three Rcp proteins. TadC abundance defects were observed in rcpA and rcpC mutants. TadD production was essential for wild-type RcpA and RcpB abundances, and RcpA did not multimerize or localize to the outer membrane without the expression of TadD. These data indicate that membrane proteins TadC and TadD may influence the assembly, transport, and/or function of individual outer membrane Rcp proteins.
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Affiliation(s)
- Sarah A Clock
- Department of Microbiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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24
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Dröge MJ, Boersma YL, Braun PG, Buining RJ, Julsing MK, Selles KGA, van Dijl JM, Quax WJ. Phage display of an intracellular carboxylesterase of Bacillus subtilis: comparison of Sec and Tat pathway export capabilities. Appl Environ Microbiol 2006; 72:4589-95. [PMID: 16820448 PMCID: PMC1489362 DOI: 10.1128/aem.02750-05] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using the phage display technology, a protein can be displayed at the surface of bacteriophages as a fusion to one of the phage coat proteins. Here we describe development of this method for fusion of an intracellular carboxylesterase of Bacillus subtilis to the phage minor coat protein g3p. The carboxylesterase gene was cloned in the g3p-based phagemid pCANTAB 5E upstream of the sequence encoding phage g3p and downstream of a signal peptide-encoding sequence. The phage-bound carboxylesterase was correctly folded and fully enzymatically active, as determined from hydrolysis of the naproxen methyl ester with Km values of 0.15 mM and 0.22 mM for the soluble and phage-displayed carboxylesterases, respectively. The signal peptide directs the encoded fusion protein to the cell membrane of Escherichia coli, where phage particles are assembled. In this study, we assessed the effects of several signal peptides, both Sec dependent and Tat dependent, on the translocation of the carboxylesterase in order to optimize the phage display of this enzyme normally restricted to the cytoplasm. Functional display of Bacillus carboxylesterase NA could be achieved when Sec-dependent signal peptides were used. Although a Tat-dependent signal peptide could direct carboxylesterase translocation across the inner membrane of E. coli, proper assembly into phage particles did not seem to occur.
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Affiliation(s)
- Melloney J Dröge
- Department of Pharmaceutical Biology, University Center of Pharmacy, Groningen University Institute for Drug Exploration (GUIDE), A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
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25
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Bennett NJ, Rakonjac J. Unlocking of the Filamentous Bacteriophage Virion During Infection is Mediated by the C Domain of pIII. J Mol Biol 2006; 356:266-73. [PMID: 16373072 DOI: 10.1016/j.jmb.2005.11.069] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 11/13/2005] [Accepted: 11/22/2005] [Indexed: 10/25/2022]
Abstract
Protein III (pIII) of filamentous phage is required for both the beginning and the end of the phage life cycle. The infection starts by binding of the N-terminal N2 and N1 domains to the primary and secondary host receptors, F pilus and TolA protein, respectively, whereas the life cycle terminates by the C-terminal domain-mediated release of the membrane-anchored virion from the cell. It has been assumed that the role of the C-terminal domain of pIII in the infection is that of a tether for the receptor-binding domains N1N2 to the main body of the virion. In a poorly understood process that follows receptor binding, the virion disassembles as its protein(s) become integrated into the host inner membrane, resulting in the phage genome entry into the bacterial cytoplasm. To begin revealing the mechanism of this process, we showed that tethering the functional N1N2 receptor-binding domain to the virion via termination-incompetent C domain abolishes infection. This infection defect cannot be complemented by in trans supply of the functional C domain. Therefore, the C domain of pIII acts in concert with the receptor-binding domains to mediate the post receptor binding events in the infection. Based on these findings, we propose a model in which binding of the N1 domain to the periplasmic portion of TolA, the secondary receptor, triggers in cis a conformational change in the C domain, and that this change opens or unlocks the pIII end of the virion, allowing the entry phase of infection to proceed. To our knowledge, this is the first virus that uses the same protein domain both for the insertion into and release from the host membrane.
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Affiliation(s)
- Nicholas J Bennett
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
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26
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Elton TC, Holland SJ, Frost LS, Hazes B. F-like type IV secretion systems encode proteins with thioredoxin folds that are putative DsbC homologues. J Bacteriol 2006; 187:8267-77. [PMID: 16321931 PMCID: PMC1316991 DOI: 10.1128/jb.187.24.8267-8277.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
F and R27 are conjugative plasmids of enteric bacteria belonging to the IncF and IncHI1 plasmid incompatibility groups, respectively. Based on sequence analysis, two genes of the F transfer region, traF and trbB, and three genes of the R27 transfer region, trhF, dsbC, and htdT, are predicted to encode periplasmic proteins containing a C-terminal thioredoxin fold. The C-X-X-C active-site motif of thioredoxins is present in all of these proteins except TraF(F). Escherichia coli carrying a dsbA mutation, which is deficient in disulfide bond formation, cannot synthesize pili and exhibits hypersensitivity to dithiothreitol (DTT) as monitored by mating ability. Overproduction of the E. coli disulfide bond isomerase DsbC, TrbB(F), DsbC(R27), or HtdT(R27), but not TraF(F) or TrhF(R27), reverses this hypersensitivity to DTT. Site-directed mutagenesis established that the C-X-X-C motif was necessary for this activity. Secretion into the periplasm of the C-terminal regions of TrbB(F) and DsbC(R27), containing putative thioredoxin folds, but not TrhF(R27), partially complemented the host dsbA mutation. A trbB(F) deletion mutant showed a 10-fold-lower mating efficiency in an E. coli dsbC null strain but had no phenotype in wild-type E. coli, suggesting redundancy in function between TrbB(F) and E. coli DsbC. Our results indicate that TrbB(F), DsbC(R27), and HtdT(R27) are putative disulfide bond isomerases for their respective transfer systems. TraF(F) is essential for conjugation but appears to have a function other than disulfide bond chemistry.
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Affiliation(s)
- Trevor C Elton
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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27
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Christie PJ, Cascales E. Structural and dynamic properties of bacterial type IV secretion systems (review). Mol Membr Biol 2005; 22:51-61. [PMID: 16092524 PMCID: PMC3921681 DOI: 10.1080/09687860500063316] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The type IV secretion systems (T4SS) are widely distributed among the gram-negative and -positive bacteria. These systems mediate the transfer of DNA and protein substrates across the cell envelope to bacterial or eukaryotic cells generally through a process requiring direct cell-to-cell contact. Bacteria have evolved T4SS for survival during establishment of pathogenic or symbiotic relationships with eukaryotic hosts. The Agrobacterium tumefaciens VirB/D4 T4SS and related conjugation machines serve as models for detailed mechanistic studies aimed at elucidating the nature of translocation signals, machine assembly pathways and architectures, and the dynamics of substrate translocation. The A. tumefaciens VirB/D4 T4SS are polar-localized organelles composed of a secretion channel and an extracellular T pilus. These T4SS are assembled from 11 or more subunits. whose membrane topologies, intersubunit contacts and, in some cases, 3-dimensional structures are known. Recently, powerful in vivo assays have identified C-terminal translocation signals, defined for the first time the translocation route for a DNA substrate through a type IV secretion channel, and supplied evidence that ATP energy consumption contributes to a late stage of machine morphogenesis. Together, these recent findings describe the mechanics of type IV secretion in unprecedented detail.
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Affiliation(s)
- Peter J Christie
- Department of Microbiology and Molecular Genetics, UT-Houston Medical School, Houston, Texas 77030, USA.
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28
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Cascales E, Christie PJ. Agrobacterium VirB10, an ATP energy sensor required for type IV secretion. Proc Natl Acad Sci U S A 2004; 101:17228-33. [PMID: 15569944 PMCID: PMC535377 DOI: 10.1073/pnas.0405843101] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Indexed: 11/18/2022] Open
Abstract
Bacteria use type IV secretion systems (T4SS) to translocate DNA and protein substrates to target cells of phylogenetically diverse taxa. Recently, by use of an assay termed transfer DNA immunoprecipitation (TrIP), we described the translocation route for a DNA substrate [T-DNA, portion of the Ti (tumor-inducing) plasmid that is transferred to plant cells] of the Agrobacterium tumefaciens VirB/D4 T4SS in terms of a series of temporally and spatially ordered substrate contacts with subunits of the secretion channel. Here, we report that the bitopic inner membrane protein VirB10 undergoes a structural transition in response to ATP utilization by the VirD4 and VirB11 ATP-binding subunits, as monitored by protease susceptibility. VirB10 interacts with inner membrane VirD4 independently of cellular energetic status, whereas the energy-induced conformational change is required for VirB10 complex formation with an outer membrane-associated heterodimer of VirB7 lipoprotein and VirB9, as shown by coimmunoprecipitation. Under these conditions, the T-DNA substrate is delivered from the inner membrane channel components VirB6 and VirB8 to periplasmic and outer membrane-associated VirB2 pilin and VirB9. We propose that VirD4 and VirB11 coordinate the ATP-dependent formation of a VirB10 "bridge" between inner and outer membrane subassemblies of the VirB/D4 T4SS, and that this morphogenetic event is required for T-DNA translocation across the A. tumefaciens cell envelope.
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Affiliation(s)
- Eric Cascales
- Department of Microbiology and Molecular Genetics, University of Texas-Houston Medical School, 6431 Fannin, Houston, TX 77030, USA
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29
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Nesper J, Hill CMD, Paiment A, Harauz G, Beis K, Naismith JH, Whitfield C. Translocation of group 1 capsular polysaccharide in Escherichia coli serotype K30. Structural and functional analysis of the outer membrane lipoprotein Wza. J Biol Chem 2003; 278:49763-72. [PMID: 14522970 DOI: 10.1074/jbc.m308775200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The late steps in assembly of capsular polysaccharides (CPS) and their translocation to the bacterial cell surface are not well understood. The Wza protein was shown previously to be required for the formation of the prototype group 1 capsule structure on the surface of Escherichia coli serotype K30 (Drummelsmith, J., and Whitfield, C. (2000) EMBO J. 19, 57-66). Wza is a conserved outer membrane lipoprotein that forms multimers adopting a ringlike structure, and collective evidence suggests a role for these structures in the export of capsular polymer across the outer membrane. Wza was purified in the native form and with a C-terminal hexahistidine tag. WzaHis6 was acylated and functional in capsule assembly, although its efficiency was slightly reduced in comparison to the native Wza protein. Ordered two-dimensional crystals of WzaHis6 were obtained after reconstitution of purified multimers into lipids. Electron microscopy of negatively stained crystals and Fourier filtering revealed ringlike multimers with an average outer diameter of 8.84 nm and an average central cavity diameter of 2.28 nm. Single particle analysis yielded projection structures at an estimated resolution of 3 nm, favoring a structure for the WzaHis6 containing eight identical subunits. A derivative of Wza (Wza*) in which the original signal sequence was replaced with that from OmpF showed that the native acylated N terminus of Wza is critical for formation of normal multimeric structures and for their competence for CPS assembly, but not for targeting Wza to the outer membrane. In the presence of Wza*, CPS accumulated in the periplasm but was not detected on the cell surface. Chemical cross-linking of intact cells suggested formation of a transmembrane complex minimally containing Wza and the inner membrane tyrosine autokinase Wzc.
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Affiliation(s)
- Jutta Nesper
- Department of Microbiology, University of Guelph, Guelph, Ontario N1G2W1, Canada
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30
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Tsuboi M, Overman SA, Nakamura K, Rodriguez-Casado A, Thomas GJ. Orientation and interactions of an essential tryptophan (Trp-38) in the capsid subunit of Pf3 filamentous virus. Biophys J 2003; 84:1969-76. [PMID: 12609899 PMCID: PMC1302766 DOI: 10.1016/s0006-3495(03)75005-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The filamentous bacteriophage Pf3 consists of a covalently closed DNA single strand of 5833 nucleotides sheathed by approximately 2500 copies of a 44-residue capsid subunit. The capsid subunit contains a single tryptophan residue (Trp-38), which is located within the basic C-terminal sequence (-RWIKAQFF) and is essential for virion assembly in vivo. Polarized Raman microspectroscopy has been employed to determine the orientation of the Trp-38 side chain in the native virus structure. The polarized Raman measurements show that the plane of the indolyl ring is tilted by 17 degrees from the virion axis and that the indolyl pseudo-twofold axis is inclined at 46 degrees to the virion axis. Using the presently determined orientation of the indolyl ring and side-chain torsion angles, chi(1) (N-C(alpha)-C(beta)-C(gamma)) and chi(2,1) (C(alpha)-C(beta)-C(gamma)-C(delta1)), we propose a detailed molecular model for the local structure of Trp-38 in the Pf3 virion. The present Pf3 model is consistent with previously reported Raman, ultraviolet-resonance Raman and fluorescence results suggesting an unusual environment for Trp-38 in the virion assembly, probably involving an intrasubunit cation-pi interaction between the guanidinium moiety of Arg-37 and the indolyl moiety of Trp-38. Such a C-terminal Trp-38/Arg-37 interaction may be important for the stabilization of a subunit conformation that is required for binding to the single-stranded DNA genome during virion assembly.
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Affiliation(s)
- Masamichi Tsuboi
- Division of Cell Biology and Biophysics, School of Biological Sciences, University of Missouri-Kansas City, 64110, USA
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31
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Opalka N, Beckmann R, Boisset N, Simon MN, Russel M, Darst SA. Structure of the filamentous phage pIV multimer by cryo-electron microscopy. J Mol Biol 2003; 325:461-70. [PMID: 12498796 DOI: 10.1016/s0022-2836(02)01246-9] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The homo-multimeric pIV protein constitutes a channel required for the assembly and export of filamentous phage across the outer membrane of Escherichia coli. We present a 22 A-resolution three-dimensional reconstruction of detergent-solubilized pIV by cryo-electron microscopy associated with image analysis. The structure reveals a barrel-like complex, 13.5 nm in diameter and 24 nm in length, with D14 point-group symmetry, consisting of a dimer of unit multimers. Side views of each unit multimer exhibit three cylindrical domains named the N-ring, the M-ring and the C-ring. Gold labeling of pIV engineered to contain a single cysteine residue near the N or C terminus unambiguously identified the N-terminal region as the N-ring, and the C-terminal region was inferred to make up the C-ring. A large pore, ranging in inner diameter from 6.0 nm to 8.8 nm, runs through the middle of the multimer, but a central domain, the pore gate, blocks it. Moreover, the pore diameter at the N-ring is smaller than the phage particle. We therefore propose that the pIV multimer undergoes a large conformational change during phage transport, with reorganization of the central domain to open the pore, and widening at the N-ring in order to accommodate the 6.5 nm diameter phage particle.
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Affiliation(s)
- Natacha Opalka
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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32
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Ast VM, Schoenhofen IC, Langen GR, Stratilo CW, Chamberlain MD, Howard SP. Expression of the ExeAB complex of Aeromonas hydrophila is required for the localization and assembly of the ExeD secretion port multimer. Mol Microbiol 2002; 44:217-31. [PMID: 11967081 DOI: 10.1046/j.1365-2958.2002.02870.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aeromonas hydrophila secretes protein toxins via the type II pathway, involving the products of at least two operons, exeAB (gspAB) and exeC-N (gspC-N). In the studies reported here, aerolysin secretion was restored to C5.84, an exeA::Tn5-751 mutant, by overexpression of exeD alone in trans. Expression studies indicated that these results did not reflect a role of ExeAB in the regulation of the exeC-N operon. Instead, immunoblot analysis showed that ExeD did not multimerize in C5.84, and fractionation of the membranes showed that the monomeric ExeD remained in the inner membrane. Expression of ExeAB, but not either protein alone, from a plasmid in C5.84 resulted in increases in the amount of multimeric ExeD, which correlated with increases in aerolysin secretion. Pulse-chase analysis also suggested that the induction of ExeAB allowed multimerization of previously accumulated monomer ExeD. In C5.84 cells overproducing ExeD, it multimerized even in the absence of ExeAB and, although most remained in the inner membrane, an amount similar to that in wild-type outer membranes fractionated with the outer membrane of the overproducing cells. These results indicate that the secretion defect of exeAB mutants is a result of an inability to assemble the ExeD secretin in the outer membrane. The localization and multimerization of overproduced ExeD in these mutants further suggests that the ExeAB complex plays either a direct or indirect role in the transport of ExeD into the outer membrane.
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Affiliation(s)
- Vivian M Ast
- Department of Biology, University of Regina, Saskatchewan, Canada
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33
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Marciano DK, Russel M, Simon SM. Assembling filamentous phage occlude pIV channels. Proc Natl Acad Sci U S A 2001; 98:9359-64. [PMID: 11459938 PMCID: PMC55425 DOI: 10.1073/pnas.161170398] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Filamentous phage f1 is exported from its Escherichia coli host without killing the bacterial cell. Phage-encoded protein pIV, which is required for phage assembly and secretion, forms large highly conductive channels in the outer membrane of E. coli. It has been proposed that the phage are extruded across the bacterial outer membrane through pIV channels. To test this prediction, we developed an in vivo assay by using a mutant pIV that functions in phage export but whose channel opens in the absence of phage extrusion. In E. coli lacking its native maltooligosacharride transporter LamB, this pIV variant allowed oligosaccharide transport across the outer membrane. This entry of oligosaccharide was decreased by phage production and still further decreased by production of phage that cannot be released from the cell surface. Thus, exiting phage block the pIV-dependent entry of oligosaccharide, suggesting that phage occupy the lumen of pIV channels. This study provides the first evidence, to our knowledge, for viral exit through a large aqueous channel.
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Affiliation(s)
- Denise K Marciano
- The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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34
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Affiliation(s)
- V T Lee
- Department of Microbiology & Immunology, UCLA School of Medicine, Los Angeles, California 90095, USA.
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35
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Abstract
The type II secretion pathway or the main terminal branch of the general secretion pathway, as it has also been referred to, is widely distributed among Proteobacteria, in which it is responsible for the extracellular secretion of toxins and hydrolytic enzymes, many of which contribute to pathogenesis in both plants and animals. Secretion through this pathway differs from most other membrane transport systems, in that its substrates consist of folded proteins. The type II secretion apparatus is composed of at least 12 different gene products that are thought to form a multiprotein complex, which spans the periplasmic compartment and is specifically required for translocation of the secreted proteins across the outer membrane. This pathway shares many features with the type IV pilus biogenesis system, including the ability to assemble a pilus-like structure. This review discusses recent findings on the organization of the secretion apparatus and the role of its various components in secretion. Different models for pilus-mediated secretion through the gated pore in the outer membrane are also presented, as are the possible properties that determine whether a protein is recognized and secreted by the type II pathway.
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Affiliation(s)
- M Sandkvist
- Department of Biochemistry, American Red Cross, Jerome H. Holland Laboratory, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.
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36
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Bamford DH, Gilbert RJ, Grimes JM, Stuart DI. Macromolecular assemblies: greater than their parts. Curr Opin Struct Biol 2001; 11:107-13. [PMID: 11179899 DOI: 10.1016/s0959-440x(00)00177-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Increasingly powerful methods of analysis have opened up complex macromolecular assemblies to scrutiny at atomic detail. They reveal not only examples of assembly from preformed and prefolded components, but also examples in which the act of assembly drives changes to the components. In the most extreme of these examples, some of the components only achieve a folded state when the complex is formed. Striking results have appeared for systems ranging from the already mature field of virus structure and assembly, where notable progress has been made for rather complex capsids, to descriptions of ribosome structures in atomic detail, where recent results have emerged at breathtaking speed.
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Affiliation(s)
- D H Bamford
- Institute of Biotechnology and Department of Biosciences, Biocentre 2 (room 6002), PO Box 56 (Viikinkaari 5), 00014 University of Helsinki, Helsinki, Finland
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37
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Arnér ES, Holmgren A. Physiological functions of thioredoxin and thioredoxin reductase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:6102-9. [PMID: 11012661 DOI: 10.1046/j.1432-1327.2000.01701.x] [Citation(s) in RCA: 1769] [Impact Index Per Article: 73.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Thioredoxin, thioredoxin reductase and NADPH, the thioredoxin system, is ubiquitous from Archea to man. Thioredoxins, with a dithiol/disulfide active site (CGPC) are the major cellular protein disulfide reductases; they therefore also serve as electron donors for enzymes such as ribonucleotide reductases, thioredoxin peroxidases (peroxiredoxins) and methionine sulfoxide reductases. Glutaredoxins catalyze glutathione-disulfide oxidoreductions overlapping the functions of thioredoxins and using electrons from NADPH via glutathione reductase. Thioredoxin isoforms are present in most organisms and mitochondria have a separate thioredoxin system. Plants have chloroplast thioredoxins, which via ferredoxin-thioredoxin reductase regulates photosynthetic enzymes by light. Thioredoxins are critical for redox regulation of protein function and signaling via thiol redox control. A growing number of transcription factors including NF-kappaB or the Ref-1-dependent AP1 require thioredoxin reduction for DNA binding. The cytosolic mammalian thioredoxin, lack of which is embryonically lethal, has numerous functions in defense against oxidative stress, control of growth and apoptosis, but is also secreted and has co-cytokine and chemokine activities. Thioredoxin reductase is a specific dimeric 70-kDa flavoprotein in bacteria, fungi and plants with a redox active site disulfide/dithiol. In contrast, thioredoxin reductases of higher eukaryotes are larger (112-130 kDa), selenium-dependent dimeric flavoproteins with a broad substrate specificity that also reduce nondisulfide substrates such as hydroperoxides, vitamin C or selenite. All mammalian thioredoxin reductase isozymes are homologous to glutathione reductase and contain a conserved C-terminal elongation with a cysteine-selenocysteine sequence forming a redox-active selenenylsulfide/selenolthiol active site and are inhibited by goldthioglucose (aurothioglucose) and other clinically used drugs.
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Affiliation(s)
- E S Arnér
- Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
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38
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Nouwen N, Stahlberg H, Pugsley AP, Engel A. Domain structure of secretin PulD revealed by limited proteolysis and electron microscopy. EMBO J 2000; 19:2229-36. [PMID: 10811614 PMCID: PMC384361 DOI: 10.1093/emboj/19.10.2229] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Secretins, a superfamily of multimeric outer membrane proteins, mediate the transport of large macromolecules across the outer membrane of Gram-negative bacteria. Limited proteolysis of secretin PulD from the Klebsiella oxytoca pullulanase secretion pathway showed that it consists of an N-terminal domain and a protease-resistant C-terminal domain that remains multimeric after proteolysis. The stable C-terminal domain starts just before the region in PulD that is highly conserved in the secretin superfamily and apparently lacks the region at the C-terminal end to which the secretin-specific pilot protein PulS binds. Electron microscopy showed that the stable fragment produced by proteolysis is composed of two stacked rings that encircle a central channel and that it lacks the peripheral radial spokes that are seen in the native complex. Moreover, the electron microscopic images suggest that the N-terminal domain folds back into the large cavity of the channel that is formed by the C-terminal domain of the native complex, thereby occluding the channel, consistent with previous electrophysiological studies showing that the channel is normally closed.
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Affiliation(s)
- N Nouwen
- Unité de Génétique Moléculaire, Centre National de la Recherche Scientifique URA 1773, 25 rue du Dr Roux, Institut Pasteur, 75724 Paris, Cedex 15, France.
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Lee HM, Wang KC, Liu YL, Yew HY, Chen LY, Leu WM, Chen DC, Hu NT. Association of the cytoplasmic membrane protein XpsN with the outer membrane protein XpsD in the type II protein secretion apparatus of Xanthomonas campestris pv. campestris. J Bacteriol 2000; 182:1549-57. [PMID: 10692359 PMCID: PMC94451 DOI: 10.1128/jb.182.6.1549-1557.2000] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An xps gene cluster composed of 11 open reading frames is required for the type II protein secretion in Xanthomonas campestris pv. campestris. Immediately upstream of the xpsD gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated ORF2) that could encode a protein of 261 amino acid residues. Its N-terminal hydrophobic region is a likely membrane-anchoring sequence. Antibody raised against this protein could detect in the wild-type strain of X. campestris pv. campestris a protein band with an apparent molecular mass of 36 kDa by Western blotting. Its aberrant slow migration in sodium dodecyl sulfate-polyacrylamide gels might be due to its high proline content. We designated this protein XpsN. By constructing a mutant strain with an in-frame deletion of the chromosomal xpsN gene, we demonstrated that it is required for the secretion of extracellular enzyme by X. campestris pv. campestris. Subcellular fractionation studies indicated that the XpsN protein was tightly associated with the membrane. Sucrose gradient sedimentation followed by immunoblot analysis revealed that it primarily appeared in the cytoplasmic membrane fractions. Immune precipitation experiments indicated that the XpsN protein was coprecipitated with the XpsD protein. In addition, the XpsN protein was co-eluted with the (His)(6)-tagged XpsD protein from the metal affinity chromatography column. All observations suggested that the XpsN protein forms a stable complex with the XpsD protein. In addition, immune precipitation analysis of the XpsN protein with various truncated XpsD proteins revealed that the C-terminal region of the XpsD protein between residues 650 and 759 was likely to be involved in complex formation between the two.
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Affiliation(s)
- H M Lee
- Graduate Institute of Agricultural Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China
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40
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Haigh NG, Webster RE. The pI and pXI assembly proteins serve separate and essential roles in filamentous phage assembly. J Mol Biol 1999; 293:1017-27. [PMID: 10547282 DOI: 10.1006/jmbi.1999.3227] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Three non-capsid, phage-encoded proteins, pI, pIV and pXI, are required for assembly of the filamentous bacteriophage at the envelope of Escherichia coli. pIV forms the outer membrane component of the assembly site, and pI and pXI are predicted to form the cytoplasmic membrane component. pXI is the result of an in-frame internal translational initiation event in gene I and is identical with the carboxyl-terminal third of pI in amino acid sequence, membrane localization and topology. The two proteins share a cytoplasmic domain predicted to be an amphipathic helix, a transmembrane domain, and a periplasmic domain. By mutating the initiation site for pXI, a phage was made that produced only pI and was shown to absolutely require functional plasmid-encoded pXI for growth. Further mutational analysis was done to examine the functional determinants of the amphipathic helix and periplasmic domains of the pI and pXI proteins. The results show that the amphipathic helix region is very important for pI function but not for pXI function. Mutational analysis of the periplasmic domains of pI and pXI implies that these domains also perform separate functions, and suggests that the interaction between pI and pIV in the periplasm is critical for assembly. The results are discussed with regard to the separate roles that the pI and pXI proteins play in the overall process of phage assembly.
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Affiliation(s)
- N G Haigh
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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