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Mossop M, Ish-Horowicz J, Hughes D, Dobra R, Cunanan AG, Rosenthal M, Carr SB, Ramadan N, Nolan LM, Davies JC. Chronicity Counts: The Impact of P. aeruginosa, S. aureus, and Co-Infection in Cystic Fibrosis. Am J Respir Crit Care Med 2024. [PMID: 38422389 DOI: 10.1164/rccm.202312-2326le] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/28/2024] [Indexed: 03/02/2024] Open
Affiliation(s)
- Micaela Mossop
- Imperial College London, 4615, National Heart and Lung Institute, London, United Kingdom of Great Britain and Northern Ireland
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland
| | - Jonathan Ish-Horowicz
- Imperial College London National Heart and Lung Institute, 90897, London, United Kingdom of Great Britain and Northern Ireland
| | - Dominic Hughes
- King's College Hospital NHS Foundation Trust, 8948, Paediatric Respiratory Medicine, London, United Kingdom of Great Britain and Northern Ireland
- Imperial College London, 4615, National heart and lung institute, London, United Kingdom of Great Britain and Northern Ireland
| | - Rebecca Dobra
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland
| | - Alessandra G Cunanan
- Imperial College London National Heart and Lung Institute, 90897, London, United Kingdom of Great Britain and Northern Ireland
| | - Mark Rosenthal
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland
| | - Siobhán B Carr
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland
| | - Newara Ramadan
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland
| | - Laura M Nolan
- Quadram Institute Bioscience, 7308, Norwich, Norfolk, United Kingdom of Great Britain and Northern Ireland
- Imperial College London National Heart and Lung Institute, 90897, London, United Kingdom of Great Britain and Northern Ireland
| | - Jane C Davies
- Imperial College London, National Heart and Lung Institute, London, United Kingdom of Great Britain and Northern Ireland
- Royal Brompton and Harefield Hospitals, 4964, London, United Kingdom of Great Britain and Northern Ireland;
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Affiliation(s)
- Amy K Cain
- Department of Molecular Sciences, Macquarie University, Sydney, NSW, Australia
| | - Laura M Nolan
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jennifer Cornick
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
| | - Karl A Hassan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
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Nolan LM, Cain AK, Clamens T, Furniss RCD, Manoli E, Sainz-Polo MA, Dougan G, Albesa-Jové D, Parkhill J, Mavridou DA, Filloux A. Identification of Tse8 as a Type VI secretion system toxin from Pseudomonas aeruginosa that targets the bacterial transamidosome to inhibit protein synthesis in prey cells. Nat Microbiol 2021; 6:1199-1210. [PMID: 34413503 PMCID: PMC7611593 DOI: 10.1038/s41564-021-00950-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 07/15/2021] [Indexed: 02/07/2023]
Abstract
The Type VI secretion system (T6SS) is a bacterial nanomachine that delivers toxic effectors to kill competitors or subvert some of their key functions. Here, we use transposon directed insertion-site sequencing to identify T6SS toxins associated with the H1-T6SS, one of the three T6SS machines found in Pseudomonas aeruginosa. This approach identified several putative toxin-immunity pairs, including Tse8-Tsi8. Full characterization of this protein pair demonstrated that Tse8 is delivered by the VgrG1a spike complex into prey cells where it targets the transamidosome, a multiprotein complex involved in protein synthesis in bacteria that lack either one, or both, of the asparagine and glutamine transfer RNA synthases. Biochemical characterization of the interactions between Tse8 and the transamidosome components GatA, GatB and GatC suggests that the presence of Tse8 alters the fine-tuned stoichiometry of the transamidosome complex, and in vivo assays demonstrate that Tse8 limits the ability of prey cells to synthesize proteins. These data expand the range of cellular components targeted by the T6SS by identifying a T6SS toxin affecting protein synthesis and validate the use of a transposon directed insertion site sequencing-based global genomics approach to expand the repertoire of T6SS toxins in T6SS-encoding bacteria.
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Affiliation(s)
- Laura M. Nolan
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Amy K. Cain
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Thomas Clamens
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - R. Christopher D. Furniss
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Maria A. Sainz-Polo
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - David Albesa-Jové
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Despoina A.I. Mavridou
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom,Department of Molecular Biosciences, University of Texas at Austin, Austin, 78712, Texas, USA,Correspondence to Alain Filloux: ; Despoina Mavridou:
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom,Correspondence to Alain Filloux: ; Despoina Mavridou:
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Turnbull L, Leigh R, Cavaliere R, Osvath SR, Nolan LM, Smyth D, Verhoeven K, Chole RA, Whitchurch CB. Device Design Modifications Informed by In Vitro Testing of Bacterial Attachment Reduce Infection Rates of Cochlear Implants in Clinical Practice. Microorganisms 2021; 9:1809. [PMID: 34576704 PMCID: PMC8471994 DOI: 10.3390/microorganisms9091809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/28/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022] Open
Abstract
Recalcitrant chronic infections of implanted medical devices are often linked to the presence of biofilms. The prevention and treatment of medical device-associated infections is a major source of antibiotic use and driver of antimicrobial resistance globally. Lowering the incidence of infection in patients that receive implanted medical devices could therefore significantly improve antibiotic stewardship and reduce patient morbidity. Here we determined if modifying the design of an implantable medical device to reduce bacterial attachment, impacted the incidence of device-associated infections in clinical practice. Since the 1980s cochlear implants have provided long-term treatment of sensorineural hearing deficiency in hundreds of thousands of patients world-wide. Nonetheless, a relatively small number of devices are surgically explanted each year due to unresolvable infections. Features associated with the accumulation of bacteria on the Cochlear™ Nucleus® CI24RE™ model of cochlear implant devices were identified using both in vitro bacterial attachment assays and examination of explanted devices. Macro-scale design modifications that reduced bacterial attachment in vitro were incorporated into the design of the CI500™ and Profile™ series of Nucleus implant. Analyses of mandatory post-market vigilance data of 198,757 CI24RE and 123,084 CI500/Profile series implantation surgeries revealed that these design modifications correlated with significantly reduced infection rates. This study demonstrates that a design-centric approach aimed at mitigating bacterial attachment was a simple, and effective means of reducing infections associated with Cochlear Nucleus devices. This approach is likely to be applicable to improving the designs of other implantable medical devices to reduce device-associated infections.
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Affiliation(s)
- Lynne Turnbull
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Roger Leigh
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Rosalia Cavaliere
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Sarah R. Osvath
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
| | - Laura M. Nolan
- National Heart and Lung Institute, Imperial College London, London SW3 6LR, UK;
| | - Daniel Smyth
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Kristien Verhoeven
- Cochlear Limited, 1 University Avenue, Macquarie University, Sydney, NSW 2109, Australia; (R.L.); (D.S.); (K.V.)
| | - Richard A. Chole
- Washington School of Medicine in St Louis, Washington University in St. Louis, St. Louis, MO 63110, USA;
| | - Cynthia B. Whitchurch
- The iThree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia; (L.T.); (R.C.); (S.R.O.)
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich NR4 7TK, UK
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Mandal PK, Ballerin G, Nolan LM, Petty NK, Whitchurch CB. Bacteriophage infection of Escherichia coli leads to the formation of membrane vesicles via both explosive cell lysis and membrane blebbing. Microbiology (Reading) 2021; 167:001021. [PMID: 33871329 PMCID: PMC8289217 DOI: 10.1099/mic.0.001021] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/01/2021] [Indexed: 12/27/2022]
Abstract
Membrane vesicles (MVs) are membrane-bound spherical nanostructures that prevail in all three domains of life. In Gram-negative bacteria, MVs are thought to be produced through blebbing of the outer membrane and are often referred to as outer membrane vesicles (OMVs). We have recently described another mechanism of MV formation in Pseudomonas aeruginosa that involves explosive cell-lysis events, which shatters cellular membranes into fragments that rapidly anneal into MVs. Interestingly, MVs are often observed within preparations of lytic bacteriophage, however the source of these MVs and their association with bacteriophage infection has not been explored. In this study we aimed to determine if MV formation is associated with lytic bacteriophage infection. Live super-resolution microscopy demonstrated that explosive cell lysis of Escherichia coli cells infected with either bacteriophage T4 or T7, resulted in the formation of MVs derived from shattered membrane fragments. Infection by either bacteriophage was also associated with the formation of membrane blebs on intact bacteria. TEM revealed multiple classes of MVs within phage lysates, consistent with multiple mechanisms of MV formation. These findings suggest that bacteriophage infection may be a major contributor to the abundance of bacterial MVs in nature.
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Affiliation(s)
- Pappu K. Mandal
- The ithree institute, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Giulia Ballerin
- The ithree institute, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Laura M. Nolan
- National Heart and Lung Institute, Imperial College London, London, SW3 6LR, UK
| | - Nicola K. Petty
- The ithree institute, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Cynthia B. Whitchurch
- The ithree institute, University of Technology Sydney, Ultimo, NSW, 2007, Australia
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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Hynen AL, Lazenby JJ, Savva GM, McCaughey LC, Turnbull L, Nolan LM, Whitchurch CB. Multiple holins contribute to extracellular DNA release in Pseudomonas aeruginosa biofilms. Microbiology (Reading) 2021; 167:000990. [PMID: 33400641 PMCID: PMC8131026 DOI: 10.1099/mic.0.000990] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/08/2020] [Indexed: 11/25/2022]
Abstract
Bacterial biofilms are composed of aggregates of cells encased within a matrix of extracellular polymeric substances (EPS). One key EPS component is extracellular DNA (eDNA), which acts as a 'glue', facilitating cell-cell and cell-substratum interactions. We have previously demonstrated that eDNA is produced in Pseudomonas aeruginosa biofilms via explosive cell lysis. This phenomenon involves a subset of the bacterial population explosively lysing, due to peptidoglycan degradation by the endolysin Lys. Here we demonstrate that in P. aeruginosa three holins, AlpB, CidA and Hol, are involved in Lys-mediated eDNA release within both submerged (hydrated) and interstitial (actively expanding) biofilms, albeit to different extents, depending upon the type of biofilm and the stage of biofilm development. We also demonstrate that eDNA release events determine the sites at which cells begin to cluster to initiate microcolony formation during the early stages of submerged biofilm development. Furthermore, our results show that sustained release of eDNA is required for cell cluster consolidation and subsequent microcolony development in submerged biofilms. Overall, this study adds to our understanding of how eDNA release is controlled temporally and spatially within P. aeruginosa biofilms.
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Affiliation(s)
- Amelia L. Hynen
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - James J. Lazenby
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - George M. Savva
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Laura C. McCaughey
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Lynne Turnbull
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - Laura M. Nolan
- National Heart and Lung Institute, Imperial College London, London, SW3 6LR, UK
| | - Cynthia B. Whitchurch
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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7
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Nolan LM, Turnbull L, Katrib M, Osvath SR, Losa D, Lazenby JJ, Whitchurch CB. Pseudomonas aeruginosa is capable of natural transformation in biofilms. Microbiology (Reading) 2020; 166:995-1003. [PMID: 32749953 PMCID: PMC7660920 DOI: 10.1099/mic.0.000956] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/11/2020] [Indexed: 12/28/2022]
Abstract
Natural transformation is a mechanism that enables competent bacteria to acquire naked, exogenous DNA from the environment. It is a key process that facilitates the dissemination of antibiotic resistance and virulence determinants throughout bacterial populations. Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that produces large quantities of extracellular DNA (eDNA) that is required for biofilm formation. P. aeruginosa has a remarkable level of genome plasticity and diversity that suggests a high degree of horizontal gene transfer and recombination but is thought to be incapable of natural transformation. Here we show that P. aeruginosa possesses homologues of all proteins known to be involved in natural transformation in other bacterial species. We found that P. aeruginosa in biofilms is competent for natural transformation of both genomic and plasmid DNA. Furthermore, we demonstrate that type-IV pili (T4P) facilitate but are not absolutely essential for natural transformation in P. aeruginosa.
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Affiliation(s)
- Laura M. Nolan
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
- National Heart and Lung Institute, Imperial College London, London, SW3 6LR, UK
| | - Lynne Turnbull
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - Marilyn Katrib
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - Sarah R. Osvath
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
| | - Davide Losa
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
- Present address: Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, TN 38123, Italy
| | - James J. Lazenby
- Microbes in the Food Chain Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Cynthia B. Whitchurch
- The ithree institute, University of Technology Sydney, Ultimo, New South Wales, 2007, Australia
- Microbes in the Food Chain Programme, Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
- School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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Wood TE, Howard SA, Förster A, Nolan LM, Manoli E, Bullen NP, Yau HCL, Hachani A, Hayward RD, Whitney JC, Vollmer W, Freemont PS, Filloux A. The Pseudomonas aeruginosa T6SS Delivers a Periplasmic Toxin that Disrupts Bacterial Cell Morphology. Cell Rep 2020; 29:187-201.e7. [PMID: 31577948 PMCID: PMC6899460 DOI: 10.1016/j.celrep.2019.08.094] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/02/2019] [Accepted: 08/27/2019] [Indexed: 01/10/2023] Open
Abstract
The type VI secretion system (T6SS) is crucial in interbacterial competition and is a virulence determinant of many Gram-negative bacteria. Several T6SS effectors are covalently fused to secreted T6SS structural components such as the VgrG spike for delivery into target cells. In Pseudomonas aeruginosa, the VgrG2b effector was previously proposed to mediate bacterial internalization into eukaryotic cells. In this work, we find that the VgrG2b C-terminal domain (VgrG2bC-ter) elicits toxicity in the bacterial periplasm, counteracted by a cognate immunity protein. We resolve the structure of VgrG2bC-ter and confirm it is a member of the zinc-metallopeptidase family of enzymes. We show that this effector causes membrane blebbing at midcell, which suggests a distinct type of T6SS-mediated growth inhibition through interference with cell division, mimicking the impact of β-lactam antibiotics. Our study introduces a further effector family to the T6SS arsenal and demonstrates that VgrG2b can target both prokaryotic and eukaryotic cells. The structure of the VgrG2b C-terminal domain presents a metallopeptidase fold VgrG2b exerts antibacterial activity in the periplasmic space Toxicity of VgrG2b is counteracted by a cognate periplasmic immunity protein VgrG2bC-ter-intoxicated prey cells bleb at the midcell and lyse
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Affiliation(s)
- Thomas E Wood
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Sophie A Howard
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Andreas Förster
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Laura M Nolan
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Nathan P Bullen
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Hamish C L Yau
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Abderrahman Hachani
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Richard D Hayward
- Division of Microbiology and Parasitology, Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, ON L8S 4K1, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
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Nolan LM, McCaughey LC, Merjane J, Turnbull L, Whitchurch CB. ChpC controls twitching motility-mediated expansion of Pseudomonas aeruginosa biofilms in response to serum albumin, mucin and oligopeptides. Microbiology (Reading) 2020; 166:669-678. [PMID: 32478653 PMCID: PMC7657506 DOI: 10.1099/mic.0.000911] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/18/2020] [Indexed: 12/31/2022]
Abstract
Twitching motility-mediated biofilm expansion occurs via coordinated, multi-cellular collective behaviour to allow bacteria to actively expand across surfaces. Type-IV pili (T4P) are cell-associated virulence factors which mediate twitching motility via rounds of extension, surface attachment and retraction. The Chp chemosensory system is thought to respond to environmental signals to regulate the biogenesis, assembly and twitching motility function of T4P. In other well characterised chemosensory systems, methyl-accepting chemotaxis proteins (MCPs) feed environmental signals through a CheW adapter protein to the histidine kinase CheA to modulate motility. The Pseudomonas aeruginosa Chp system has an MCP PilJ and two CheW adapter proteins, PilI and ChpC, that likely interact with the histidine kinase ChpA to feed environmental signals into the system. In the current study we show that ChpC is involved in the response to host-derived signals serum albumin, mucin and oligopeptides. We demonstrate that these signals stimulate an increase in twitching motility, as well as in levels of 3'-5'-cyclic adenosine monophosphate (cAMP) and surface-assembled T4P. Interestingly, our data shows that changes in cAMP and surface piliation levels are independent of ChpC but that the twitching motility response to these environmental signals requires ChpC. Furthermore, we show that protease activity is required for the twitching motility response of P. aeruginosa to environmental signals. Based upon our data we propose a model whereby ChpC feeds these environmental signals into the Chp system, potentially via PilJ or another MCP, to control twitching motility. PilJ and PilI then modulate T4P surface levels to allow the cell to continue to undergo twitching motility. Our study is the first to link environmental signals to the Chp chemosensory system and refines our understanding of how this system controls twitching motility-mediated biofilm expansion in P. aeruginosa.
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Affiliation(s)
- Laura M. Nolan
- The ithree institute, University of Technology Sydney, Ultimo 2007, New South Wales, Australia
- National Heart and Lung Institute, Imperial College London, London SW3 6LR, UK
| | - Laura C. McCaughey
- The ithree institute, University of Technology Sydney, Ultimo 2007, New South Wales, Australia
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Jessica Merjane
- The ithree institute, University of Technology Sydney, Ultimo 2007, New South Wales, Australia
| | - Lynne Turnbull
- The ithree institute, University of Technology Sydney, Ultimo 2007, New South Wales, Australia
| | - Cynthia B. Whitchurch
- The ithree institute, University of Technology Sydney, Ultimo 2007, New South Wales, Australia
- Microbes in the Food Chain Programme, Quadram Institute Bioscience, Norwich Research Park, NR4 7UQ and School of Biological Sciences, University of East Anglia, NR4 7TJ, Norwich, UK
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Strickland SL, Varekojis SM, Goodfellow LT, Wilgis J, W Hayashi S, Nolan LM, Burton GG. Physician Support for Non-Physician Advanced Practice Providers for Persons With Cardiopulmonary Disease. Respir Care 2020; 65:1702-1711. [PMID: 32606076 DOI: 10.4187/respcare.07387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND The use of non-physician advanced practice providers (NPAPP) has increased in the United States to offset shortages in the physician workforce. Yet there are still gaps in some locations where there is little to no access to quality health care. This study sought to identify whether physicians perceived a workforce gap and their level of interest in hiring an NPAPP with cardiopulmonary expertise to fill the perceived gap. METHODS An American Association for Respiratory Care (AARC)-led workgroup surveyed 1,401 physicians in 6 different specialties. The survey instrument contained 32 closed-ended questions and 4 open-ended questions. RESULTS 74% of the 1,401 physician respondents agreed or strongly agreed that there will be a future need for an NPAPP with cardiopulmonary expertise. Respondents from sleep, pediatrics, pulmonary, and critical care were most likely to indicate that there is a current need for an NPAPP. A majority of respondents perceived that the specialized NPAPP would improve efficiency and productivity (74%), patient experience (73%), and patient outcomes (72%). Interest in adding this NPAPP did not increase when participants were told to presume authority for hiring, budget, and reimbursement. CONCLUSIONS These results indicate that there is both a need for and an interest in hiring an NPAPP with cardiopulmonary expertise. Having an NPAPP would boost physician efficiency and productivity, improve the patient care experience, and provide benefits that other clinicians are not trained to provide to persons with cardiopulmonary disease. Results suggest there should be continued efforts to develop the NPAPP role to add value for physicians and patients alike.
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Affiliation(s)
| | | | | | - John Wilgis
- Florida Hospital Association, Orlando, Florida
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11
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Allsopp LP, Bernal P, Nolan LM, Filloux A. Causalities of war: The connection between type VI secretion system and microbiota. Cell Microbiol 2020; 22:e13153. [PMID: 31872954 PMCID: PMC7540082 DOI: 10.1111/cmi.13153] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/23/2019] [Accepted: 12/19/2019] [Indexed: 12/14/2022]
Abstract
Microbiota niches have space and/or nutrient restrictions, which has led to the coevolution of cooperation, specialisation, and competition within the population. Different animal and environmental niches contain defined resident microbiota that tend to be stable over time and offer protection against undesired intruders. Yet fluxes can occur, which alter the composition of a bacterial population. In humans, the microbiota are now considered a key contributor to maintenance of health and homeostasis, and its alteration leads to dysbiosis. The bacterial type VI secretion system (T6SS) transports proteins into the environment, directly into host cells or can function as an antibacterial weapon by killing surrounding competitors. Upon contact with neighbouring cells, the T6SS fires, delivering a payload of effector proteins. In the absence of an immunity protein, this results in growth inhibition or death of prey leading to a competitive advantage for the attacker. It is becoming apparent that the T6SS has a role in modulating and shaping the microbiota at multiple levels, which is the focus of this review. Discussed here is the T6SS, its role in competition, key examples of its effect upon the microbiota, and future avenues of research.
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Affiliation(s)
- Luke P Allsopp
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Patricia Bernal
- Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - Laura M Nolan
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
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Cain AK, Nolan LM, Sullivan GJ, Whitchurch CB, Filloux A, Parkhill J. Complete Genome Sequence of Pseudomonas aeruginosa Reference Strain PAK. Microbiol Resour Announc 2019; 8:e00865-19. [PMID: 31601664 PMCID: PMC6787321 DOI: 10.1128/mra.00865-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 09/09/2019] [Indexed: 11/29/2022] Open
Abstract
We report the complete genome of Pseudomonas aeruginosa strain PAK, a strain which has been instrumental in the study of a range of P. aeruginosa virulence and pathogenesis factors and has been used for over 50 years as a laboratory reference strain.
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Affiliation(s)
- Amy K Cain
- Wellcome Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Department of Molecular Sciences, Macquarie University, North Ryde, Australia
| | - Laura M Nolan
- Imperial College London, MRC Centre for Molecular Bacteriology and Infection, South Kensington, London, United Kingdom
| | | | - Cynthia B Whitchurch
- The ithree institute, Faculty of Science, University of Technology Sydney, Ultimo, Australia
| | - Alain Filloux
- Imperial College London, MRC Centre for Molecular Bacteriology and Infection, South Kensington, London, United Kingdom
| | - Julian Parkhill
- Wellcome Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
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Lorenz A, Preuße M, Bruchmann S, Pawar V, Grahl N, Pils MC, Nolan LM, Filloux A, Weiss S, Häussler S. Importance of flagella in acute and chronicPseudomonas aeruginosainfections. Environ Microbiol 2018; 21:883-897. [DOI: 10.1111/1462-2920.14468] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Anne Lorenz
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Molecular Bacteriology, TWINCORE GmbHCenter for Clinical and Experimental Infection Research Hannover Germany
| | - Matthias Preuße
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Molecular Bacteriology, TWINCORE GmbHCenter for Clinical and Experimental Infection Research Hannover Germany
| | - Sebastian Bruchmann
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Molecular Bacteriology, TWINCORE GmbHCenter for Clinical and Experimental Infection Research Hannover Germany
- Wellcome Sanger Institute Cambridge UK
| | - Vinay Pawar
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Immunology, Medical School Hannover Hannover Germany
| | - Nora Grahl
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Molecular Bacteriology, TWINCORE GmbHCenter for Clinical and Experimental Infection Research Hannover Germany
| | - Marina C. Pils
- Mouse PathologyAnimal Experimental Unit, Helmholtz Centre for Infection Research Braunschweig Germany
| | - Laura M. Nolan
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life SciencesImperial College London London UK
| | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life SciencesImperial College London London UK
| | - Siegfried Weiss
- Institute of Immunology, Medical School Hannover Hannover Germany
| | - Susanne Häussler
- Institute of Molecular BacteriologyHelmholtz Centre for Infection Research Braunschweig Germany
- Institute of Molecular Bacteriology, TWINCORE GmbHCenter for Clinical and Experimental Infection Research Hannover Germany
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Nolan LM, Whitchurch CB, Barquist L, Katrib M, Boinett CJ, Mayho M, Goulding D, Charles IG, Filloux A, Parkhill J, Cain AK. A global genomic approach uncovers novel components for twitching motility-mediated biofilm expansion in Pseudomonas aeruginosa. Microb Genom 2018; 4. [PMID: 30383525 PMCID: PMC6321873 DOI: 10.1099/mgen.0.000229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pseudomonas aeruginosa is an extremely successful pathogen able to cause both acute and chronic infections in a range of hosts, utilizing a diverse arsenal of cell-associated and secreted virulence factors. A major cell-associated virulence factor, the Type IV pilus (T4P), is required for epithelial cell adherence and mediates a form of surface translocation termed twitching motility, which is necessary to establish a mature biofilm and actively expand these biofilms. P. aeruginosa twitching motility-mediated biofilm expansion is a coordinated, multicellular behaviour, allowing cells to rapidly colonize surfaces, including implanted medical devices. Although at least 44 proteins are known to be involved in the biogenesis, assembly and regulation of the T4P, with additional regulatory components and pathways implicated, it is unclear how these components and pathways interact to control these processes. In the current study, we used a global genomics-based random-mutagenesis technique, transposon directed insertion-site sequencing (TraDIS), coupled with a physical segregation approach, to identify all genes implicated in twitching motility-mediated biofilm expansion in P. aeruginosa. Our approach allowed identification of both known and novel genes, providing new insight into the complex molecular network that regulates this process in P. aeruginosa. Additionally, our data suggest that the flagellum-associated gene products have a differential effect on twitching motility, based on whether components are intra- or extracellular. Overall the success of our TraDIS approach supports the use of this global genomic technique for investigating virulence genes in bacterial pathogens.
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Affiliation(s)
- Laura M Nolan
- 1MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Cynthia B Whitchurch
- 2The ithree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Lars Barquist
- 3Institute for Molecular Infection Biology, University of Würzburg, Würzburg D-97080, Germany.,4Helmholtz Institute for RNA-based Infection Research (HIRI), Würzburg, Germany
| | - Marilyn Katrib
- 2The ithree Institute, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Christine J Boinett
- 5Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK.,†Present address: Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Matthew Mayho
- 5Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - David Goulding
- 5Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Ian G Charles
- 6Quadram Institute of Bioscience, Norwich Research Park, Norwich, Norfolk NR4 7UA, UK
| | - Alain Filloux
- 1MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Julian Parkhill
- 5Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Amy K Cain
- 5Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK.,‡Present address: Chemical and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
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Nolan LM, Cavaliere R, Turnbull L, Whitchurch CB. Extracellular ATP inhibits twitching motility-mediated biofilm expansion by Pseudomonas aeruginosa. BMC Microbiol 2015; 15:55. [PMID: 25879216 PMCID: PMC4355966 DOI: 10.1186/s12866-015-0392-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 02/18/2015] [Indexed: 11/10/2022] Open
Abstract
Background Pseudomonas aeruginosa is an opportunistic pathogen that exploits damaged epithelia to cause infection. Type IV pili (tfp) are polarly located filamentous structures which are the major adhesins for attachment of P. aeruginosa to epithelial cells. The extension and retraction of tfp powers a mode of surface translocation termed twitching motility that is involved in biofilm development and also mediates the active expansion of biofilms across surfaces. Extracellular adenosine triphosphate (eATP) is a key “danger” signalling molecule that is released by damaged epithelial cells to alert the immune system to the potential presence of pathogens. As P. aeruginosa has a propensity for infecting damaged epithelial tissues we have explored the influence of eATP on tfp biogenesis and twitching motility-mediated biofilm expansion by P. aeruginosa. Results In this study we have found that eATP inhibits P. aeruginosa twitching motility-mediated expansion of interstitial biofilms at levels that are not inhibitory to growth. We have determined that eATP does not inhibit expression of the tfp major subunit, PilA, but reduces the levels of surface assembled tfp. We have also determined that the active twitching zone of expanding P. aeruginosa interstitial biofilms contain large quantities of eATP which may serve as a signalling molecule to co-ordinate cell movements in the expanding biofilm. The inhibition of twitching motility-mediated interstitial biofilm expansion requires eATP hydrolysis and does not appear to be mediated by the Chp chemosensory system. Conclusions Endogenous eATP produced by P. aeruginosa serves as a signalling molecule to co-ordinate complex multicellular behaviours of this pathogen. Given the propensity for P. aeruginosa to infect damaged epithelial tissues, our observations suggest that eATP released by damaged cells may provide a cue to reduce twitching motility of P. aeruginosa in order to establish infection at the site of damage. Furthermore, eATP produced by P. aeruginosa biofilms and by damaged epithelial cells may play a role in P. aeruginosa pathogenesis by inducing inflammatory damage and fibrosis. Our findings have significant implications in the development and pathogenesis of P. aeruginosa biofilm infections. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0392-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Laura M Nolan
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia.
| | - Rosalia Cavaliere
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia.
| | - Lynne Turnbull
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia.
| | - Cynthia B Whitchurch
- The ithree institute, University of Technology Sydney, PO Box 123, Broadway, NSW, 2007, Australia.
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Nolan LM, Beatson SA, Croft L, Jones PM, George AM, Mattick JS, Turnbull L, Whitchurch CB. Extragenic suppressor mutations that restore twitching motility to fimL mutants of Pseudomonas aeruginosa are associated with elevated intracellular cyclic AMP levels. Microbiologyopen 2012; 1:490-501. [PMID: 23233287 PMCID: PMC3535393 DOI: 10.1002/mbo3.49] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/21/2012] [Accepted: 11/01/2012] [Indexed: 01/19/2023] Open
Abstract
Cyclic AMP (cAMP) is a signaling molecule that is involved in the regulation of multiple virulence systems of the opportunistic pathogen Pseudomonas aeruginosa. The intracellular concentration of cAMP in P. aeruginosa cells is tightly controlled at the levels of cAMP synthesis and degradation through regulation of the activity and/or expression of the adenylate cyclases CyaA and CyaB or the cAMP phosphodiesterase CpdA. Interestingly, mutants of fimL, which usually demonstrate defective twitching motility, frequently revert to a wild-type twitching-motility phenotype presumably via the acquisition of an extragenic suppressor mutation(s). In this study, we have characterized five independent fimL twitching-motility revertants and have determined that all have increased intracellular cAMP levels compared with the parent fimL mutant. Whole-genome sequencing revealed that only one of these fimL revertants has acquired a loss-of-function mutation in cpdA that accounts for the elevated levels of intracellular cAMP. As mutation of cpdA did not account for the restoration of twitching motility observed in the other four fimL revertants, these observations suggest that there is at least another, as yet unidentified, site of extragenic suppressor mutation that can cause phenotypic reversion in fimL mutants and modulation of intracellular cAMP levels of P. aeruginosa.
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Affiliation(s)
- Laura M Nolan
- The ithree institute, University of Technology Sydney, Sydney, New South Wales, 2007, Australia
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Coleman NV, Yau S, Wilson NL, Nolan LM, Migocki MD, Ly MA, Crossett B, Holmes AJ. Untangling the multiple monooxygenases of Mycobacterium chubuense strain NBB4, a versatile hydrocarbon degrader. Environ Microbiol Rep 2011; 3:297-307. [PMID: 23761275 DOI: 10.1111/j.1758-2229.2010.00225.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Mycobacterium strain NBB4 was isolated on ethene as part of a bioprospecting study searching for novel monooxygenase (MO) enzymes of interest to biocatalysis and bioremediation. Previous work indicated that strain NBB4 contained an unprecedented diversity of MO genes, and we hypothesized that each MO type would support growth on a distinct hydrocarbon substrate. Here, we attempted to untangle the relationships between MO types and hydrocarbon substrates. Strain NBB4 was shown to grow on C2 -C4 alkenes and C2 -C16 alkanes. Complete gene clusters encoding six different monooxygenases were recovered from a fosmid library, including homologues of ethene MO (etnABCD), propene MO (pmoABCD), propane MO (smoABCD), butane MO (smoXYB1C1Z), cytochrome P450 (CYP153; fdx-cyp-fdr) and alkB (alkB-rubA1-rubA2). Catabolic enzymes involved in ethene assimilation (EtnA, EtnC, EtnD, EtnE) and alkane assimilation (alcohol and aldehyde dehydrogenases) were identified by proteomics, and we showed for the first time that stress response proteins (catalase/peroxidase, chaperonins) were induced by growth on C2 -C5 alkanes and ethene. Surprisingly, none of the identified MO genes could be specifically associated with oxidation of small alkanes, and thus the nature of the gaseous alkane MO in NBB4 remains mysterious.
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Affiliation(s)
- Nicholas V Coleman
- School of Molecular Bioscience, Building G08, University of Sydney, Sydney, NSW 2006, Australia
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Keseler IM, Bonavides-Martínez C, Collado-Vides J, Gama-Castro S, Gunsalus RP, Johnson DA, Krummenacker M, Nolan LM, Paley S, Paulsen IT, Peralta-Gil M, Santos-Zavaleta A, Shearer AG, Karp PD. EcoCyc: a comprehensive view of Escherichia coli biology. Nucleic Acids Res 2008; 37:D464-70. [PMID: 18974181 PMCID: PMC2686493 DOI: 10.1093/nar/gkn751] [Citation(s) in RCA: 256] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
EcoCyc (http://EcoCyc.org) provides a comprehensive encyclopedia of Escherichia coli biology. EcoCyc integrates information about the genome, genes and gene products; the metabolic network; and the regulatory network of E. coli. Recent EcoCyc developments include a new initiative to represent and curate all types of E. coli regulatory processes such as attenuation and regulation by small RNAs. EcoCyc has started to curate Gene Ontology (GO) terms for E. coli and has made a dataset of E. coli GO terms available through the GO Web site. The curation and visualization of electron transfer processes has been significantly improved. Other software and Web site enhancements include the addition of tracks to the EcoCyc genome browser, in particular a type of track designed for the display of ChIP-chip datasets, and the development of a comparative genome browser. A new Genome Omics Viewer enables users to paint omics datasets onto the full E. coli genome for analysis. A new advanced query page guides users in interactively constructing complex database queries against EcoCyc. A Macintosh version of EcoCyc is now available. A series of Webinars is available to instruct users in the use of EcoCyc.
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Affiliation(s)
- Ingrid M Keseler
- SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025, USA
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Abstract
The discovery of a powerful immunosuppressive, cyclosporin A, together with the development of a microsurgical free tissue transfer technique, has brought extremity transplantation closer to being a realistic possibility. In this review the authors describe the history of laboratory research into extremity transplantation before immunosuppression, with early immunosuppressive agents, with cyclosporin A, and with FK-506, one of a new generation of immunosuppressives.
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Affiliation(s)
- L M Nolan
- Division of Orthopaedic Surgery, University of Toronto, Toronto General Hospital, Ontario, Canada
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Abstract
The immature rabbit knee model for epiphyseal plate transplantations has been used by a number of investigators. Rigid fixation of the femoral osteosynthesis has been difficult to achieve reliably. This paper describes a new technique for obtaining consistent and satisfactory skeletal fixation in this model. The tibia was internally fixed with an ASIF/AO four-hole minifragment plate. The femur was fixed with a 2.4 mm Steinman pin supplemented with two 26 gauge stainless steel interosseous wire loops placed at right angles to each other.
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Affiliation(s)
- L M Nolan
- Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada
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