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Bennett MR, Moloney C, Catrambone F, Turco F, Myers B, Kovacs K, Hill PJ, Alexander C, Rawson FJ, Gurnani P. Oxygen-Tolerant RAFT Polymerization Initiated by Living Bacteria. ACS Macro Lett 2022; 11:954-960. [PMID: 35819106 PMCID: PMC9387098 DOI: 10.1021/acsmacrolett.2c00372] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 11/29/2022]
Abstract
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Living organisms can synthesize a wide range of macromolecules
from a small set of natural building blocks, yet there is potential
for even greater materials diversity by exploiting biochemical processes
to convert unnatural feedstocks into new abiotic polymers. Ultimately,
the synthesis of these polymers in situ might aid the coupling of
organisms with synthetic matrices, and the generation of biohybrids
or engineered living materials. The key step in biohybrid materials
preparation is to harness the relevant biological pathways to produce
synthetic polymers with predictable molar masses and defined architectures
under ambient conditions. Accordingly, we report an aqueous, oxygen-tolerant
RAFT polymerization platform based on a modified Fenton reaction,
which is initiated by Cupriavidus metallidurans CH34,
a bacterial species with iron-reducing capabilities. We show the synthesis
of a range of water-soluble polymers under normoxic conditions, with
control over the molar mass distribution, and also the production
of block copolymer nanoparticles via polymerization-induced self-assembly.
Finally, we highlight the benefits of using a bacterial initiation
system by recycling the cells for multiple polymerizations. Overall,
our method represents a highly versatile approach to producing well-defined
polymeric materials within a hybrid natural-synthetic polymerization
platform and in engineered living materials with properties beyond
those of biotic macromolecules.
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Affiliation(s)
- Mechelle R Bennett
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Cara Moloney
- School of Medicine, BioDiscovery Institute, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Francesco Catrambone
- School of Life Sciences, BioDiscovery Institute, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Federico Turco
- School of Pharmacy, BioDiscovery Institute, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Benjamin Myers
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Katalin Kovacs
- Division of Molecular Therapeutics, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Philip J Hill
- Division of Microbiology, Brewing and Biotechnology, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Nottingham LE12 5RD, United Kingdom
| | - Cameron Alexander
- Division of Molecular Therapeutics, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Frankie J Rawson
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
| | - Pratik Gurnani
- Division of Molecular Therapeutics, School of Pharmacy, University of Nottingham, University Park Campus, Nottingham NG7 2RD, United Kingdom
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Ahmad J, Jayet B, Hill PJ, Mather ML, Dehghani H, Morgan SP. Ultrasound-mediation of self-illuminating reporters improves imaging resolution in optically scattering media. Biomed Opt Express 2018; 9:1664-1679. [PMID: 29675309 PMCID: PMC5905913 DOI: 10.1364/boe.9.001664] [Citation(s) in RCA: 2] [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] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/13/2017] [Accepted: 02/12/2018] [Indexed: 06/08/2023]
Abstract
In vivo imaging of self-illuminating bio-and chemiluminescent reporters is used to observe the physiology of small animals. However, strong light scattering by biological tissues results in poor spatial resolution of the optical imaging, which also degrades the quantitative accuracy. To overcome this challenging problem, focused ultrasound is used to modulate the light from the reporter at the ultrasound frequency. This produces an ultrasound switchable light 'beacon' that reduces the influence of light scattering in order to improve spatial resolution. The experimental results demonstrate that apart from light modulation at the ultrasound frequency (AC signal at 3.5 MHz), ultrasound also increases the DC intensity of the reporters. This is shown to be due to a temperature rise caused by insonification that was minimized to be within acceptable mammalian tissue safety thresholds by adjusting the duty cycle of the ultrasound. Line scans of bio-and chemiluminescent objects embedded within a scattering medium were obtained using ultrasound modulated (AC) and ultrasound enhanced (DC) signals. Lateral resolution is improved by a factor of 12 and 7 respectively, as compared to conventional CCD imaging. Two chemiluminescent sources separated by ~10 mm at ~20 mm deep inside a 50 mm thick chicken breast have been successfully resolved with an average signal-to-noise ratio of approximately 8-10 dB.
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Affiliation(s)
- Junaid Ahmad
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, University Park, NG7 2RD, UK
- Department of Electrical Engineering, University of Engineering and Technology, Lahore, KSK Campus, 54890, Pakistan
| | - Baptiste Jayet
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, University Park, NG7 2RD, UK
| | - Philip J Hill
- School of Biosciences, University of Nottingham, LE12 5RD, UK
| | - Melissa L Mather
- Institute of Science and Technology in Medicine, Keele University, ST4 7QB, UK
| | - Hamid Dehghani
- School of Computer Science, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Stephen P Morgan
- Optics and Photonics Research Group, Faculty of Engineering, University of Nottingham, University Park, NG7 2RD, UK
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Iqbal M, Doherty N, Page AML, Qazi SNA, Ajmera I, Lund PA, Kypraios T, Scott DJ, Hill PJ, Stekel DJ. Reconstructing promoter activity from Lux bioluminescent reporters. PLoS Comput Biol 2017; 13:e1005731. [PMID: 28922354 PMCID: PMC5619816 DOI: 10.1371/journal.pcbi.1005731] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 09/28/2017] [Accepted: 08/19/2017] [Indexed: 11/19/2022] Open
Abstract
The bacterial Lux system is used as a gene expression reporter. It is fast, sensitive and non-destructive, enabling high frequency measurements. Originally developed for bacterial cells, it has also been adapted for eukaryotic cells, and can be used for whole cell biosensors, or in real time with live animals without the need for euthanasia. However, correct interpretation of bioluminescent data is limited: the bioluminescence is different from gene expression because of nonlinear molecular and enzyme dynamics of the Lux system. We have developed a computational approach that, for the first time, allows users of Lux assays to infer gene transcription levels from the light output. This approach is based upon a new mathematical model for Lux activity, that includes the actions of LuxAB, LuxEC and Fre, with improved mechanisms for all reactions, as well as synthesis and turn-over of Lux proteins. The model is calibrated with new experimental data for the LuxAB and Fre reactions from Photorhabdus luminescens—the source of modern Lux reporters—while literature data has been used for LuxEC. Importantly, the data show clear evidence for previously unreported product inhibition for the LuxAB reaction. Model simulations show that predicted bioluminescent profiles can be very different from changes in gene expression, with transient peaks of light output, very similar to light output seen in some experimental data sets. By incorporating the calibrated model into a Bayesian inference scheme, we can reverse engineer promoter activity from the bioluminescence. We show examples where a decrease in bioluminescence would be better interpreted as a switching off of the promoter, or where an increase in bioluminescence would be better interpreted as a longer period of gene expression. This approach could benefit all users of Lux technology. Bioluminescent reporters are used in many areas of biology as fast, sensitive and non-destructive measures of gene expression. They have been developed for bacteria, adapted now for other kinds of organisms, and recently been used for whole cell biosensors, and for real-time live animal models for infection without the need for euthanasia. However, users of Lux technologies rely on the light output being similar to the gene expression they wish to measure. We show that this is not the case. Rather, there is a nonlinear relationship between the two: light output can be misleading and so limits the way that such data can be interpreted. We have developed a new computational method that, for the first time, allows users of Lux reporters to infer accurate gene transcription levels from bioluminescent data. We show examples where a small decrease in light would be better interpreted as promoter being switched off, or where an increase in light would be better interpreted as promoter activity for a longer time.
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Affiliation(s)
- Mudassar Iqbal
- Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Neil Doherty
- Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Anna M. L. Page
- Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Saara N. A. Qazi
- Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Ishan Ajmera
- Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Peter A. Lund
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Theodore Kypraios
- School of Mathematical Sciences, University of Nottingham, Nottingham, United Kingdom
| | - David J. Scott
- Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Philip J. Hill
- Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
| | - Dov J. Stekel
- Agricultural and Environmental Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, United Kingdom
- * E-mail:
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Betts HM, Milicevic Sephton S, Tong C, Awais RO, Hill PJ, Perkins AC, Aigbirhio FI. Synthesis, in Vitro Evaluation, and Radiolabeling of Fluorinated Puromycin Analogues: Potential Candidates for PET Imaging of Protein Synthesis. J Med Chem 2016; 59:9422-9430. [PMID: 27690460 DOI: 10.1021/acs.jmedchem.6b00968] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
There is currently no ideal radiotracer for imaging of protein synthesis rate (PSR) by positron emission tomography (PET). Existing fluorine-18-labeled amino acid-based radiotracers predominantly visualize amino acid transporter processes, and in many cases they are not incorporated into nascent proteins at all. Others are radiolabeled with the short-half-life positron emitter carbon-11, which is rather impractical for many PET centers. Based on the puromycin (6) structural manifold, a series of 10 novel derivatives of 6 was prepared via Williamson ether synthesis from a common intermediate. A bioluminescence assay was employed to study their inhibitory action on protein synthesis, which identified the fluoroethyl analogue 7b as a lead compound. The fluorine-18 analogue was prepared via nucleophilic substitution of the corresponding tosylate precursor in a modest radiochemical yield of 2 ± 0.6% with excellent radiochemical purity (>99%) and showed complete stability over 3 h at ambient temperature.
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Affiliation(s)
- Helen M Betts
- Nottingham University Hospitals NHS Trust, PET/CT Center, Nottingham City Hospital , Hucknall Road, Nottingham NG5 1PB, U.K
| | - Selena Milicevic Sephton
- Molecular Imaging Chemistry Laboratory, Wolfson Brain Imaging Center, University of Cambridge , Box 65 Cambridge Biomedical Campus, Cambridge CB2 0QQ, U.K
| | - Carmen Tong
- School of Life Sciences, University of Nottingham , University Park, Nottingham NG7 2RD, U.K
| | - Ramla O Awais
- Radiological Sciences, School of Medicine, University of Nottingham, Queen's Medical Center , Derby Road, Nottingham NG7 2UH, U.K
| | - Philip J Hill
- School of Biosciences, University of Nottingham , Sutton Bonington Campus, Sutton Bonington LE12 5RD, U.K
| | - Alan C Perkins
- Radiological Sciences, School of Medicine, University of Nottingham, Queen's Medical Center , Derby Road, Nottingham NG7 2UH, U.K
| | - Franklin I Aigbirhio
- Molecular Imaging Chemistry Laboratory, Wolfson Brain Imaging Center, University of Cambridge , Box 65 Cambridge Biomedical Campus, Cambridge CB2 0QQ, U.K
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Takahashi H, Oshima T, Hobman JL, Doherty N, Clayton SR, Iqbal M, Hill PJ, Tobe T, Ogasawara N, Kanaya S, Stekel DJ. The dynamic balance of import and export of zinc in Escherichia coli suggests a heterogeneous population response to stress. J R Soc Interface 2016; 12:rsif.2015.0069. [PMID: 25808337 PMCID: PMC4424684 DOI: 10.1098/rsif.2015.0069] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [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] [Indexed: 11/12/2022] Open
Abstract
Zinc is essential for life, but toxic in excess. Thus all cells must control their internal zinc concentration. We used a systems approach, alternating rounds of experiments and models, to further elucidate the zinc control systems in Escherichia coli. We measured the response to zinc of the main specific zinc import and export systems in the wild-type, and a series of deletion mutant strains. We interpreted these data with a detailed mathematical model and Bayesian model fitting routines. There are three key findings: first, that alternate, non-inducible importers and exporters are important. Second, that an internal zinc reservoir is essential for maintaining the internal zinc concentration. Third, our data fitting led us to propose that the cells mount a heterogeneous response to zinc: some respond effectively, while others die or stop growing. In a further round of experiments, we demonstrated lower viable cell counts in the mutant strain tested exposed to excess zinc, consistent with this hypothesis. A stochastic model simulation demonstrated considerable fluctuations in the cellular levels of the ZntA exporter protein, reinforcing this proposal. We hypothesize that maintaining population heterogeneity could be a bet-hedging response allowing a population of cells to survive in varied and fluctuating environments.
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Affiliation(s)
- Hiroki Takahashi
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Chiba 260-8673, Japan
| | - Taku Oshima
- Graduate School of Biological Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan
| | - Jon L Hobman
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
| | - Neil Doherty
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
| | - Selina R Clayton
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
| | - Mudassar Iqbal
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
| | - Philip J Hill
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
| | - Toru Tobe
- Laboratory of Molecular Medical Microbiology, Department of Biomedical Informatics, Osaka University Graduate School of Medicine, 1-7 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Naotake Ogasawara
- Graduate School of Biological Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan
| | - Shigehiko Kanaya
- Graduate School of Information Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0192, Japan
| | - Dov J Stekel
- School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Loughborough LE12 5RD, UK
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Mills B, Awais RO, Luckett J, Turton D, Williams P, Perkins AC, Hill PJ. [(18)F]FDG-6-P as a novel in vivo tool for imaging staphylococcal infections. EJNMMI Res 2015; 5:13. [PMID: 25853019 PMCID: PMC4385282 DOI: 10.1186/s13550-015-0095-1] [Citation(s) in RCA: 11] [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] [Received: 01/28/2015] [Accepted: 03/04/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Management of infection is a major clinical problem. Staphylococcus aureus is a Gram-positive bacterium which colonises approximately one third of the adult human population. Staphylococcal infections can be life-threatening and are frequently complicated by multi-antibiotic resistant strains including methicillin-resistant S. aureus (MRSA). Fluorodeoxyglucose ([(18)F]FDG) imaging has been used to identify infection sites; however, it is unable to distinguish between sterile inflammation and bacterial load. We have modified [(18)F]FDG by phosphorylation, producing [(18)F]FDG-6-P to facilitate specific uptake and accumulation by S. aureus through hexose phosphate transporters, which are not present in mammalian cell membranes. This approach leads to the specific uptake of the radiopharmaceutical into the bacteria and not the sites of sterile inflammation. METHODS [(18)F]FDG-6-P was synthesised from [(18)F]FDG. Yield, purity and stability were confirmed by RP-HPLC and iTLC. The specificity of [(18)F]FDG-6-P for the bacterial universal hexose phosphate transporter (UHPT) was confirmed with S. aureus and mammalian cell assays in vitro. Whole body biodistribution and accumulation of [(18)F]FDG-6-P at the sites of bioluminescent staphylococcal infection were established in a murine foreign body infection model. RESULTS In vitro validation assays demonstrated that [(18)F]FDG-6-P was stable and specifically transported into S. aureus but not mammalian cells. [(18)F]FDG-6-P was elevated at the sites of S. aureus infection in vivo compared to uninfected controls; however, the increase in signal was not significant and unexpectedly, the whole-body biodistribution of [(18)F]FDG-6-P was similar to that of [(18)F]FDG. CONCLUSIONS Despite conclusive in vitro validation, [(18)F]FDG-6-P did not behave as predicted in vivo. However at the site of known infection, [(18)F]FDG-6-P levels were elevated compared with uninfected controls, providing a higher signal-to-noise ratio. The bacterial UHPT can transport hexose phosphates other than glucose, and therefore alternative sugars may show differential biodistribution and provide a means for specific bacterial detection.
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Affiliation(s)
- Bethany Mills
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Boulevard, Nottingham, NG7 2RD UK
| | - Ramla O Awais
- School of Medicine, University of Nottingham, Nottingham, NG7 2RD UK
| | - Jeni Luckett
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Boulevard, Nottingham, NG7 2RD UK ; School of Medicine, University of Nottingham, Nottingham, NG7 2RD UK
| | - Dave Turton
- PETNET Solutions, Nottingham City Hospital, Hucknall Road, Nottingham, NG5 1 PB UK
| | - Paul Williams
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, University Boulevard, Nottingham, NG7 2RD UK
| | - Alan C Perkins
- School of Medicine, University of Nottingham, Nottingham, NG7 2RD UK
| | - Philip J Hill
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, LE12 5RD UK
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Brown A, Horobin A, Blount DG, Hill PJ, English J, Rich A, Williams PM, Pritchard DI. Blow fly Lucilia sericata nuclease digests DNA associated with wound slough/eschar and with Pseudomonas aeruginosa biofilm. Med Vet Entomol 2012; 26:432-439. [PMID: 22827809 DOI: 10.1111/j.1365-2915.2012.01029.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In chronic wounds, it may be clinically important to remove extracellular bacterial and patient DNA as its presence may impede wound healing and promote bacterial survival in biofilm, in which extracellular DNA forms part of the biofilm architecture. As medicinal maggots, larvae of Lucilia sericata Meigen (Diptera: Calliphoridae) have been shown to efficiently debride wounds it became of interest to investigate their excretions/secretions (ES) for the presence of a deoxyribonuclease (DNAse) activity. Excretions/secretions products were shown to contain a DNAse, with magnesium, sodium and calcium metal ion dependency, and a native molecular mass following affinity purification of approximately 45 kDa. The affinity purified DNAse degraded genomic bacterial DNA per se, DNA from the slough/eschar of a venous leg ulcer, and extracellular bacterial DNA in biofilms pre-formed from a clinical isolate of Pseudomonas aeruginosa. The latter finding highlights an important attribute of the DNAse, given the frequency of P. aeruginosa infection in non-healing wounds and the fact that P. aeruginosa virulence factors can be toxic to maggots. Maggot DNAse is thus a competent enzyme derived from a rational source, with the potential to assist in clinical wound debridement by removing extracellular DNA from tissue and biofilm, and promoting tissue viability, while liberating proteinaceous slough/eschar for debridement by the suite of proteinases secreted by L. sericata.
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Affiliation(s)
- A Brown
- School of Pharmacy, University of Nottingham, Nottingham, U.K
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Liu Q, Hill PJ, Karamitri A, Ryan KJP, Chen HY, Lomax MA. Construction of a doxycycline inducible adipogenic lentiviral expression system. Plasmid 2012; 69:96-103. [PMID: 23099229 PMCID: PMC3556778 DOI: 10.1016/j.plasmid.2012.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/02/2012] [Accepted: 10/15/2012] [Indexed: 11/11/2022]
Abstract
To provide a tool for research on regulating adipocyte differentiation, tetracycline inducible (Tet on) lentiviral expression vectors under the control of an adipose-specific promoter were constructed. The lowest basal expression in the absence of doxycycline and most efficient dose-dependent, doxycycline-induced transient overexpression was observed using vectors constructed with a combination of Tetracycline Responsive Element (TRE) and reverse tetracycline-controlled TransActivator advanced (rtTAadv), transfected in white (3T3-L1) and brown (HIB-1B) preadipocytes cell lines. The results demonstrate that doxycycline adipogenic inducible expression can be achieved using a pLenti TRE / rtTA adv under the control of the truncated aP2 promoter in HIB-1B preadipocytes.
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Affiliation(s)
- Q Liu
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, United Kingdom
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Thurman J, Parry J, Hill PJ, Priscu JC, Vick TJ, Chiuchiolo A, Laybourn-Parry J. Microbial dynamics and flagellate grazing during transition to winter in Lakes Hoare and Bonney, Antarctica. FEMS Microbiol Ecol 2012; 82:449-58. [PMID: 22671290 DOI: 10.1111/j.1574-6941.2012.01423.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 03/28/2012] [Accepted: 05/25/2012] [Indexed: 11/26/2022] Open
Abstract
The planktonic microbial communities of Lakes Hoare and Bonney were investigated during transition into winter. We hypothesized that the onset of darkness induces changes in the functional role of autotrophic and heterotrophic microplankton. Bacteria decreased in Lake Hoare during March-April, while in Lake Bonney bacterial abundances varied. Heterotrophic nanoflagellates (HNAN), phototrophic nanoflagellates (PNAN) and ciliates showed no marked decline with the onset of winter. PNAN outnumbered HNAN in both lakes. Grazing rates of HNAN in Lake Hoare ranged up to 30.8 bacteria per cell day(-1). The HNAN community grazed between 3.74 and 36.6 ng of bacterial carbon day(-1). Mixotrophic PNAN had grazing rates up to 15.2 bacteria per cell day(-1), and their daily community grazing exceeded bacterial production. In Lake Bonney East, PNAN grazing rates ranged up to 12.48 bacteria per cell day(-1) and in Lake Bonney West up to 8.16 bacteria per cell day(-1). As in Lake Hoare, the mixotrophic PNAN grazing rates (up to 950 ng C day(-1)) usually exceeded bacterial production. HNAN grazing rates were generally similar to those in Lake Hoare. As winter encroaches, these lakes move progressively towards heterotrophy and probably function during the winter, enabling populations to enter the short austral summer with actively growing populations.
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Affiliation(s)
- Jill Thurman
- Division of Biomedical and Life Sciences, School of Health and Medicine, University of Lancaster, Lancaster, UK
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Thurman J, Parry JD, Hill PJ, Laybourn-Parry J. The Filter-Feeding Ciliates Colpidium striatum and Tetrahymena pyriformis Display Selective Feeding Behaviours in the Presence of Mixed, Equally-Sized, Bacterial Prey. Protist 2010; 161:577-88. [DOI: 10.1016/j.protis.2010.04.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 02/21/2010] [Indexed: 10/19/2022]
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Stritzker J, Hill PJ, Gentschev I, Szalay AA. Myristoylation negative msbB-mutants of probiotic E. coli Nissle 1917 retain tumor specific colonization properties but show less side effects in immunocompetent mice. Bioeng Bugs 2009; 1:139-45. [PMID: 21326939 DOI: 10.4161/bbug.1.2.10286] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 10/07/2009] [Accepted: 10/09/2009] [Indexed: 12/13/2022] Open
Abstract
Specific colonization of solid tumors by bacteria opens the way to novel approaches in both tumor diagnosis and therapy. However, even non-pathogenic bacteria induce responses by the immune system, which could be devastating for a tumor bearing patient. As such effects are caused e.g., by the lipid A moiety of the lipopolysaccharide, a msbB-mutant of the probiotic E. coli Nissle 1917 strain was investigated. Bacteria of the mutant strain did not show any growth defects in culture media when compared to wild-type E. coli Nissle 1917 but were unable to myristoylate lipid A, had less toxic effects on immunocompetent BALB/c mice, and were still able to specifically colonize tumors. Therefore, the modification of lipid A could result in bacterial strains that might be better suited for diagnosis and therapy of tumors than the corresponding wild-type strains, even if those are not considered pathogenic or are of probiotic background.
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Perehinec TM, Qazi SNA, Gaddipati SR, Salisbury V, Rees CED, Hill PJ. Construction and evaluation of multisite recombinatorial (Gateway) cloning vectors for Gram-positive bacteria. BMC Mol Biol 2007; 8:80. [PMID: 17880697 PMCID: PMC2039747 DOI: 10.1186/1471-2199-8-80] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 09/19/2007] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The Gateway recombinatorial cloning system allows easy and rapid joining of DNA fragments. Here we report the construction and evaluation of three different Gram-positive vectors that can be used with the Multisite Gateway cloning system to rapidly produce new gene arrangements in plasmid constructs for use in a variety of Gram-positive bacteria. RESULTS Comparison of patterns of reporter gene expression with conventionally constructed clones show that the presence of residual recombination (att) sites does not have an effect on patterns of gene expression, although overall levels of gene expression may vary. Rapid construction of these new vectors allowed vector/gene combinations to be optimized following evaluation of plasmid constructs in different bacterial cells and demonstrates the benefits of plasmid construction using Gateway cloning. CONCLUSION The residual att sites present after Gateway cloning did not affect patterns of promoter induction in Gram-positive bacteria and there was no evidence of differences in mRNA stability of transcripts. However overall levels of gene expression may be reduced, possibly due to some post-transcriptional event. The new vectors described here allow faster, more efficient cloning in range of Gram-positive bacteria.
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Affiliation(s)
- Tania M Perehinec
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK
| | - Saara NA Qazi
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Sanyasi R Gaddipati
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK
| | - Vyvyan Salisbury
- Faculty of Applied Sciences, University of the West of England, Bristol, UK
| | - Catherine ED Rees
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK
| | - Philip J Hill
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK
- Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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13
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Stritzker J, Weibel S, Hill PJ, Oelschlaeger TA, Goebel W, Szalay AA. Tumor-specific colonization, tissue distribution, and gene induction by probiotic Escherichia coli Nissle 1917 in live mice. Int J Med Microbiol 2007; 297:151-62. [PMID: 17448724 DOI: 10.1016/j.ijmm.2007.01.008] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 01/24/2007] [Accepted: 01/26/2007] [Indexed: 11/20/2022] Open
Abstract
Systemic administration of microorganisms into tumor-bearing mice revealed preferential accumulation in tumors in comparison to clearance in organs such as spleen and liver. Here we compared the efficiency of tumor-specific colonization of pathogenic Salmonella typhimurium strains 14028 and SL1344 to the enteroinvasive Escherichia coli 4608-58 strain and to the attenuated Salmonella flexneri 2a SC602 strain, as well as to the uropathogenic E. coli CFT073, the non-pathogenic E. coli Top10, and the probiotic E. coli Nissle 1917 strain. All strains colonized and replicated in tumors efficiently each resulting in more than 1 x 10(8) colony-forming units per gram tumor tissue. Colonization of spleen and liver were significantly lower when E. coli strains were used in comparison to S. typhimurium and the non-pathogenic strains did not colonize those organs at all. Further investigation of E. coli Nissle 1917 showed that no drastic differences in colonization and amplification were seen when immunocompetent and immunocompromised animals were used, and we were able to show that E. coli Nissle 1917 replicates at the border of live and necrotic tumor tissue. We also demonstrated exogenously applied L-arabinose-dependent gene activation in colonized tumors in live mice. These findings will prepare the way for bacterium-mediated controlled protein delivery to solid tumors.
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Affiliation(s)
- Jochen Stritzker
- Genelux Corporation, 3030 Bunker Hill St., Ste. 310, San Diego, CA 92109, USA
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14
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Abstract
A high-throughput system to rapidly assess the intracellular replication of Staphylococcus aureus has been developed utilizing S. aureus transformed with a dual gfp-luxABCDE reporter operon under the control of a growth-dependent promoter. Replication of tagged bacteria internalized into bovine mammary epithelial cells (MAC-T) could be measured by monitoring fluorescence and bioluminescence from the reporter operon following removal of extracellular bacteria from the plates. Bacterial replication inside cells was confirmed by a novel ex vivo time-lapse confocal microscopic method. This assay of bacterial replication was used to evaluate the efficacy of antibiotics which are commonly used to treat staphylococcal infections. Not all antibiotics tested were able to prevent intracellular replication of S. aureus and some were ineffective at preventing replication of intracellular bacteria at concentrations above the MIC determined for bacteria in broth culture. Comparison of the fluorescence and bioluminescence signals from the bacteria enabled effects on protein synthesis and metabolism to be discriminated and gave information on the entry of compounds into the eukaryotic cell, even if bacterial replication was not prevented. Elevated resistance of S. aureus to antibiotics inside host cells increases the likelihood of selecting S. aureus strains which are resistant to commonly used antimicrobial agents within the intracellular niche. The approach presented directly assesses intracellular efficacy of antibiotics and provides an evidence-based approach to antibiotic selection for prescribing physicians and medical microbiologists.
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Affiliation(s)
- S N A Qazi
- Institute of Infection, Immunity, and Inflammation. Institute of Cell Signalling, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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15
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Abstract
Antifreeze proteins (AFPs) are a structurally diverse group of proteins that have the ability to modify ice crystal structure and inhibit recrystallization of ice. AFPs are well characterized in fish and insects, but very few bacterial species have been shown to have AFP activity to date. Thirty eight freshwater to hypersaline lakes in the Vestfold Hills and Larsemann Hills of Eastern Antarctica were sampled for AFPs during 2000. Eight hundred and sixty six bacterial isolates were cultivated. A novel AFP assay, designed for high-throughput analysis in Antarctica, demonstrated putative activity in 187 of the cultures. Subsequent analysis of the putative positive isolates showed 19 isolates with significant recrystallization inhibition (RI) activity. The 19 RI active isolates were characterized using ARDRA (amplified rDNA restriction analysis) and 16S rDNA sequencing. They belong to genera from the alpha- and gamma-Proteobacteria, with genera from the gamma-subdivision being predominant. The 19 AFP-active isolates were isolated from four physico-chemically diverse lakes. Ace Lake and Oval Lake were both meromictic with correspondingly characteristic chemically stratified water columns. Pendant Lake was a saline holomictic lake with different chemical properties to the two meromictic lakes. Triple Lake was a hypersaline lake rich in dissolved organic carbon and inorganic nutrients. The environments from which the AFP-active isolates were isolated are remarkably diverse. It will be of interest, therefore, to elucidate the evolutionary forces that have led to the acquisition of functional AFP activity in microbes of the Vestfold Hills lakes and to discover the role the antifreezes play in these organisms.
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Affiliation(s)
- Jack A Gilbert
- School of Life and Environmental Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
| | - Philip J Hill
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
| | - Christine E R Dodd
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK
| | - Johanna Laybourn-Parry
- School of Life and Environmental Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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16
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Abstract
Clp proteolytic complexes are essential for virulence and for survival under stress conditions in several pathogenic bacteria. Recently, a study using signature-tagged mutagenesis identified the ClpX ATPase as also being required for virulence in Staphylococcus aureus. Presently, we have constructed deletion mutants removing either ClpX or the proteolytic subunit, ClpP, in S. aureus 8325-4 in order to examine a putative link between stress tolerance and virulence. When exposed to stress, we found that, although clpP mutant cells were sensitive to conditions generating misfolded proteins, the absence of ClpX improved survival. In the presence of oxidative stress or at low temperature, both ClpP and ClpX were important for growth. Virulence was examined in a murine skin abscess model and was found to be severely attenuated for both mutants. S. aureus pathogenicity is largely dependent on a set of extracellular and cell wall-associated proteins. In the mutant cells, the amount of alpha-haemolysin (hla) and several other extracellular proteins was greatly decreased, and analysis of hla expression revealed that the reduction occurred at the transcriptional level. Essential for transcriptional regulation of hla is the quorum-sensing agr locus. Interestingly, the absence of ClpX or ClpP reduced both transcription of the agr effector molecule, RNA III, and the activity of the autoinducing peptide (AIP). In addition, ClpX was required independently of ClpP for transcription of spa encoding Protein A. Thus, our results indicate that ClpX and ClpP contribute to virulence by controlling the activity of major virulence factors rather than by promoting stress tolerance.
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Affiliation(s)
- Dorte Frees
- Department of Veterinary Microbiology, Royal Veterinary and Agricultural University (KVL), Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark
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17
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Abstract
The microbial diversity occurring in Stilton cheese was evaluated by 16S ribosomal DNA analysis with PCR-denaturing gradient gel electrophoresis. DNA templates for PCR experiments were directly extracted from the cheese as well as bulk cells harvested from a variety of viable-count media. The variable V3 and V4-V5 regions of the 16S genes were analyzed. Closest relatives of Lactococcus lactis, Enterococcus faecalis, Lactobacillus plantarum, Lactobacillus curvatus, Leuconostoc mesenteroides, Staphylococcus equorum, and Staphylococcus sp. were identified by sequencing of the DGGE fragments. Fluorescently labeled oligonucleotide probes were developed to detect Lactococcus lactis, Lactobacillus plantarum, and Leuconostoc mesenteroides in fluorescence in situ hybridization (FISH) experiments, and their specificity for the species occurring in the community of Stilton cheese was checked in FISH experiments carried out with reference cultures. The combined use of these probes and the bacterial probe Eub338 in FISH experiments on Stilton cheese sections allowed the assessment of the spatial distribution of the different microbial species in the dairy matrix. Microbial colonies of bacteria showed a differential location in the different parts of the cheese examined: the core, the veins, and the crust. Lactococci were found in the internal part of the veins as mixed colonies and as single colonies within the core. Lactobacillus plantarum was detected only underneath the surface, while Leuconostoc microcolonies were homogeneously distributed in all parts observed. The combined molecular approach is shown to be useful to simultaneously describe the structure and location of the bacterial flora in cheese. The differential distribution of species found suggests specific ecological reasons for the establishment of sites of actual microbial growth in the cheese, with implications of significance in understanding the ecology of food systems and with the aim of achieving optimization of the fermentation technologies as well as preservation of traditional products.
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Affiliation(s)
- Danilo Ercolini
- Division of Food Sciences, School of Biosciences, University of Nottingham, Loughborough, Leicestershire LE12 5RD, United Kingdom
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18
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Abstract
A 16S rRNA fluorescence in situ hybridization (FISH) method for cheese was developed to allow detection in situ of microorganisms within the dairy matrix. An embedding procedure using a plastic resin was applied to Stilton cheese, providing intact embedded cheese sections withstanding the hybridization reaction. The use of a fluorescein-labelled 16S rRNA Domain Bacteria probe allowed observation of large colonies of microbial cells homogeneously distributed in the cheese matrix. FISH experiments performed on cheese suspensions provided images of the different microbial morphotypes occurring. The technique has great potential to study the spatial distribution of microbial populations in situ in foods, especially where the matrix is too fragile to allow manipulation of cryosections.
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Affiliation(s)
- Danilo Ercolini
- Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE125RD, UK
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19
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Morrissey JA, Cockayne A, Hammacott J, Bishop K, Denman-Johnson A, Hill PJ, Williams P. Conservation, surface exposure, and in vivo expression of the Frp family of iron-regulated cell wall proteins in Staphylococcus aureus. Infect Immun 2002; 70:2399-407. [PMID: 11953376 PMCID: PMC127940 DOI: 10.1128/iai.70.5.2399-2407.2002] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis identified two conserved, immunogenic Staphylococcus aureus cell wall proteins, of 40 and 87 kDa, expressed under iron-restricted growth conditions in vitro and in vivo. N-terminal sequencing and subsequent genome analysis showed that these proteins are encoded by adjacent monocistronic open reading frames designated frpA and frpB, respectively. Studies with an S. aureus fur mutant confirmed that expression of FrpA and FrpB is regulated by Fur but that there also appears to be differential expression of these proteins in different iron-restricted media in vitro. FrpA and FrpB share some amino acid sequence homology with each other and with a putative S. aureus membrane protein, FrpC. frpC is the first gene of a Fur-regulated operon encoding four proteins of unknown function (FrpC, -D, -G, and -H) and the binding protein (FrpE) and permease (FrpF) of a putative iron transporter. Antisense mutagenesis and bioassays showed that FrpA and FrpB are not required for growth of S. aureus under iron-restricted conditions in vitro and do not appear to be involved in the transport of iron from siderophores or in binding of hemin. Further phenotypic analysis suggested that FrpA may be involved in adhesion of S. aureus to plastic in vitro. Binding of S. aureus to microtiter wells was found to be iron regulated, and iron-restricted S. aureus containing antisense frpA or frpAB but not frpB constructs showed reduced binding compared to vector construct controls.
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Affiliation(s)
- Julie A Morrissey
- Institute of Infections and Immunity, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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20
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Winzer K, Hardie KR, Burgess N, Doherty N, Kirke D, Holden MTG, Linforth R, Cornell KA, Taylor AJ, Hill PJ, Williams P. LuxS: its role in central metabolism and the in vitro synthesis of 4-hydroxy-5-methyl-3(2H)-furanone. Microbiology (Reading) 2002; 148:909-922. [PMID: 11932438 DOI: 10.1099/00221287-148-4-909] [Citation(s) in RCA: 274] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many bacteria produce extracellular molecules which function in cell-to-cell communication. One of these molecules, autoinducer 2 (AI-2), was first described as an extracellular signal produced by Vibrio harveyi to control luciferase expression. Subsequently, a number of bacteria have been shown to possess AI-2 activity in their culture supernatants, and bear the luxS gene product, which is required for AI-2 synthesis. In Porphyromonas gingivalis, luxS and pfs, encoding a 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTA/SAH'ase), form an operon, suggesting that S-adenosylhomocysteine (SAH) or 5'-methylthioadenosine (MTA) serves as a substrate for AI-2 production. Cell-free extracts of Escherichia coli MG1655, but not DH5alpha (which carries a luxS frame-shift mutation) were capable of generating AI-2 activity upon addition of SAH, but not MTA. S-Ribosyl-homocysteine (RH) derived from SAH also served as a substrate in E. coli MG1655 extracts. RH-supplemented cell-free extracts of Pseudomonas aeruginosa, a bacterium that lacks luxS, only generated AI-2 activity following the introduction of a plasmid containing the Por. gingivalis pfs-luxS operon. In addition, defined in vitro systems consisting of the purified LuxS proteins from Por. gingivalis, E. coli, Neisseria meningitidis or Staphylococcus aureus converted RH to homocysteine and a compound that exhibits AI-2 activity.4-Hydroxy-5-methyl-3(2H)-furanone was identified by mass spectrometry analysis as a major product formed in this in vitro reaction. In E. coli MG1655, expression of T3SH [the bacteriophage T3 S-adenosylmethionine (SAM) hydrolase] significantly reduced AI-2 activity in culture supernatants, suggesting that AI-2 production is limited by the amount of SAH produced in SAM-dependent transmethylase reactions. The authors suggest that the LuxS protein has an important metabolic function in the recycling of SAH. They also show that Ps. aeruginosa is capable of removing AI-2 activity, implying that this molecule may act as a nutrient. In many bacteria AI-2 may in fact represent not a signal molecule but a metabolite which is released early and metabolized in the later stages of growth.
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Affiliation(s)
- Klaus Winzer
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Kim R Hardie
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Nicola Burgess
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Neil Doherty
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - David Kirke
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
| | - Matthew T G Holden
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Rob Linforth
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
| | - Kenneth A Cornell
- Immunology Research, R&D 21, VA Medical Center, Portland, OR 97201, USA4
| | - Andrew J Taylor
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
| | - Philip J Hill
- School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK3
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
| | - Paul Williams
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK2
- Institute of Infections and Immunity, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK1
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21
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Qazi SN, Counil E, Morrissey J, Rees CE, Cockayne A, Winzer K, Chan WC, Williams P, Hill PJ. agr expression precedes escape of internalized Staphylococcus aureus from the host endosome. Infect Immun 2001; 69:7074-82. [PMID: 11598083 PMCID: PMC100088 DOI: 10.1128/iai.69.11.7074-7082.2001] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a versatile pathogen capable of causing life-threatening infections. Many of its cell wall and exoproduct virulence determinants are controlled via the accessory gene regulator (agr). Although considered primarily as an extracellular pathogen, it is now recognized that S. aureus can be internalized by epithelial and endothelial cells. Traditional experimental approaches to investigate bacterial internalization are extremely time-consuming and notoriously irreproducible. We present here a new reporter gene method to assess intracellular growth of S. aureus in MAC-T cells that utilizes a gfp-luxABCDE reporter operon under the control of the Bacillus megaterium xylA promoter, which in S. aureus is expressed in a growth-dependent manner. This facilitates assessment of the growth of internalized bacteria in a nondestructive assay. The dual gfp-lux reporter cassette was also evaluated as a reporter of agr expression and used to monitor the temporal induction of agr during the MAC-T internalization process. The data obtained suggest that agr induction occurs prior to endosomal lysis and that agr-regulated exoproteins appear to be required prior to the release and replication of S. aureus within the infected MAC-T cells.
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Affiliation(s)
- S N Qazi
- School of Biosciences, University of Nottingham, Loughborough, Leicestershire LE12 5RD, United Kingdom
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22
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MDowell P, Affas Z, Reynolds C, Holden MT, Wood SJ, Saint S, Cockayne A, Hill PJ, Dodd CE, Bycroft BW, Chan WC, Williams P. Structure, activity and evolution of the group I thiolactone peptide quorum-sensing system of Staphylococcus aureus. Mol Microbiol 2001; 41:503-12. [PMID: 11489134 DOI: 10.1046/j.1365-2958.2001.02539.x] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Staphylococcus aureus, the agr locus is responsible for controlling virulence gene expression via quorum sensing. As the blockade of quorum sensing offers a novel strategy for attenuating infection, we sought to gain novel insights into the structure, activity and turnover of the secreted staphylococcal autoinducing peptide (AIP) signal molecules. A series of analogues (including the L-alanine and D-amino acid scanned peptides) was synthesized to determine the functionally critical residues within the S. aureus group I AIP. As a consequence, we established that (i) the group I AIP is inactivated in culture supernatants by the formation of the corresponding methionyl sulphoxide; and (ii) the group I AIP lactam analogue retains the capacity to activate agr, suggesting that covalent modification of the AgrC receptor is not a necessary prerequisite for agr activation. Although each of the D-amino acid scanned AIP analogues retained activity, replacement of the endocyclic amino acid residue (aspartate) located C-terminally to the central cysteine with alanine converted the group I AIP from an activator to a potent inhibitor. The screening of clinical S. aureus isolates for novel AIP groups revealed a variant that differed from the group I AIP by a single amino acid residue (aspartate to tyrosine) in the same position defined as critical by alanine scanning. Although this AIP inhibits group I S. aureus strains, the producer strains possess a functional agr locus dependent on the endogenous peptide and, as such, constitute a fourth S. aureus AIP pheromone group (group IV). The addition of exogenous synthetic AIPs to S. aureus inhibited the production of toxic shock syndrome toxin (TSST-1) and enterotoxin C3, confirming the potential of quorum-sensing blockade as a therapeutic strategy.
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Affiliation(s)
- P MDowell
- Institute of Infections and Immunity, School of Pharmaceutical Sciences, and School of BioSciences, University of Nottingham, Nottingham NG7 2RD, UK
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23
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Jones BW, Means TK, Heldwein KA, Keen MA, Hill PJ, Belisle JT, Fenton MJ. Different Toll-like receptor agonists induce distinct macrophage responses. J Leukoc Biol 2001; 69:1036-44. [PMID: 11404392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
We previously reported that gram-negative bacterial lipopolysaccharide (LPS) activates cells via Toll-like receptor (TLR) 4, whereas the mycobacterial cell wall glycolipid lipoarabinomannan (LAM) activates cells via TLR2. We also identified a secreted TLR2 agonist activity in short-term culture filtrates of Mycobacterium tuberculosis bacilli, termed soluble tuberculosis factor (STF). Here we show that STF contains mannosylated phosphatidylinositol (PIM) and that purified PIM possesses TLR2 agonist activity. Stimulation of RAW 264.7 macrophages by LPS, LAM, STF, and PIM rapidly activated nuclear factor (NF)-kappaB, activator protein-1 (AP-1), and mitogen-activated protein (MAP) kinases. These TLR agonists induced similar levels of NF-kappaB and AP-1 DNA-binding activity, as well as trans-activation function. Unexpectedly, these TLR agonists induced tumor necrosis factor alpha secretion, whereas only LPS was capable of inducing interleukin-1beta and nitric oxide secretion. Thus, different TLR proteins are still capable of activating distinct cellular responses, in spite of their shared capacities to activate NF-kappaB, AP-1, and MAP kinases.
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Affiliation(s)
- B W Jones
- The Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts, USA
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24
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Abstract
From a mass-excised Staphylococcus aureus lambdaZapII expression library, we cloned an operon encoding a novel ABC transporter with significant homology to bacterial siderophore transporter systems. The operon encodes four genes designated sstA, -B, -C, and -D encoding two putative cytoplasmic membrane proteins (sstA and sstB), an ATPase (sstC), and a membrane-bound 38-kDa lipoprotein (sstD). The sst operon is preceded by two putative Fur boxes, which indicated that expression of the sst operon was likely to be iron dependent. SstD was overexpressed in Escherichia coli, purified by Triton X-114 phase partitioning, and used to generate monospecific antisera in rats. Immunoblotting studies located SstD in the membrane fraction of S. aureus and showed that expression of the lipoprotein was reduced under iron-rich growth conditions. Triton X-114 partitioning studies on isolated membranes provided additional biochemical evidence that SstD in S. aureus is a lipoprotein. Immunoreactive polypeptides of approximately 38 kDa were detected in a wide range of staphylococcal species, but no antigenic homolog was detected in Bacillus subtilis. Expression of SstD in vivo was confirmed by immunoblotting studies with S. aureus recovered from a rat intraperitoneal chamber implant model. To further define the contribution of SstD in promoting growth of S. aureus in vitro and in vivo, we used antisense RNA technology to modulate expression of SstD. Expression of antisense sstD RNA in S. aureus resulted in a decrease in SstD expression under both iron-rich and iron-restricted growth conditions. However, this reduction in SstD levels did not affect the growth of S. aureus in vitro in an iron-limited growth medium or when grown in an intraperitoneal rat chamber implant model in vivo.
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Affiliation(s)
- J A Morrissey
- Institute of Infections and Immunity, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
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25
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Ciarciaglini G, Hill PJ, Davies K, McClure PJ, Kilsby D, Brown MH, Coote PJ. Germination-induced bioluminescence, a route to determine the inhibitory effect of a combination preservation treatment on bacterial spores. Appl Environ Microbiol 2000; 66:3735-42. [PMID: 10966384 PMCID: PMC92214 DOI: 10.1128/aem.66.9.3735-3742.2000] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2000] [Accepted: 06/07/2000] [Indexed: 11/20/2022] Open
Abstract
In this work, we have used spores of Bacillus subtilis that specifically induce bioluminescence upon initiation of germination as a rapid, real-time monitor of the effects of preservative treatments on germination. Using this tool, we have demonstrated that the combination of mild acidity (pH 5.5 to 5.0), lactic acid (0. 5%), and a pasteurization step (90 degrees C for 5 min) results in enhanced inhibition of spore germination compared with the effects of the individual treatments alone. Inhibition by the combination treatment occurred as a result of both direct but reversible inhibition, entirely dependent on the physical presence of the preservative factors, and permanent, nonreversible damage to the L-alanine germination apparatus of the spore. However, we were able to restore germination of the preservative-damaged spores unable to germinate on L-alanine by supplementing the medium with the nonnutrient germinant calcium dipicolinic acid. The demonstration that simple combinations of preservative factors inhibit spore germination indicates that food preservation systems providing ambient stability could be designed which do not adhere to the strict limits set by commonly accepted processes and which are based on precise understanding of their inhibitory action.
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Affiliation(s)
- G Ciarciaglini
- Microbiology Department, Unilever Research Colworth, Sharnbrook, Bedford MK44 1LQ, United Kingdom
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26
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Juffermans NP, Verbon A, Belisle JT, Hill PJ, Speelman P, van Deventer SJ, van der Poll T. Mycobacterial lipoarabinomannan induces an inflammatory response in the mouse lung. A role for interleukin-1. Am J Respir Crit Care Med 2000; 162:486-9. [PMID: 10934075 DOI: 10.1164/ajrccm.162.2.9911009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Lipoarabinomannan (LAM), a cell wall component of Mycobacterium tuberculosis, induces the production of cytokines and chemokines in vitro. Interleukin-1 (IL-1) contributes to granuloma formation in tuberculosis (TB), and exerts effects via the IL-1 receptor type I (IL-1R). To determine the effects of LAM in the pulmonary compartment in vivo and to establish the role of endogenous IL-1 herein, normal and IL-1R deficient ((-/-)) mice were intranasally inoculated with LAM (50 microgram). In normal mice, LAM resulted in a neutrophilic cell influx into the bronchoalveolar lavage fluid (BALF). LAM also induced increases in the lung concentrations of macrophage inflammatory protein-2 (MIP-2), keratinocyte (KC), tumor necrosis factor-alpha (TNF-alpha), IL-1alpha, and IL-1beta. IL-1R(-/-) mice had less influx of granulocytes in their BALF than wild-type mice. Also, lung TNF-alpha levels were lower in IL-1R(-/-) mice. LAM may be an important stimulator of innate immunity in infection with M. tuberculosis via mechanisms that involve endogenous IL-1 activity.
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Affiliation(s)
- N P Juffermans
- Laboratory of Experimental Internal Medicine, Department of Internal Medicine, Division of Infectious Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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27
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Colangeli R, Spencer JS, Bifani P, Williams A, Lyashchenko K, Keen MA, Hill PJ, Belisle J, Gennaro ML. MTSA-10, the product of the Rv3874 gene of Mycobacterium tuberculosis, elicits tuberculosis-specific, delayed-type hypersensitivity in guinea pigs. Infect Immun 2000; 68:990-3. [PMID: 10639479 PMCID: PMC97238 DOI: 10.1128/iai.68.2.990-993.2000] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In a search for new skin test reagents specific for tuberculosis, we found that the antigen encoded by gene Rv3874 of Mycobacterium tuberculosis elicited delayed-type hypersensitivity in M. tuberculosis-infected guinea pigs but not in control animals immunized with Mycobacterium bovis bacillus Calmette-Guérin (BCG) or Mycobacterium avium. The antigen, which was named MTSA-10 (for M. tuberculosis-specific antigen 10), is a prime candidate for a component of a new tuberculin that will allow discrimination by a skin test of latent M. tuberculosis infection from vaccination with BCG or from sensitization with environmental, nontuberculous mycobacteria.
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Affiliation(s)
- R Colangeli
- Public Health Research Institute, New York, New York 10016, USA
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Holden MT, Ram Chhabra S, de Nys R, Stead P, Bainton NJ, Hill PJ, Manefield M, Kumar N, Labatte M, England D, Rice S, Givskov M, Salmond GP, Stewart GS, Bycroft BW, Kjelleberg S, Williams P. Quorum-sensing cross talk: isolation and chemical characterization of cyclic dipeptides from Pseudomonas aeruginosa and other gram-negative bacteria. Mol Microbiol 1999; 33:1254-66. [PMID: 10510239 DOI: 10.1046/j.1365-2958.1999.01577.x] [Citation(s) in RCA: 377] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In cell-free Pseudomonas aeruginosa culture supernatants, we identified two compounds capable of activating an N-acylhomoserine lactone (AHL) biosensor. Mass spectrometry and NMR spectroscopy revealed that these compounds were not AHLs but the diketopiperazines (DKPs), cyclo(DeltaAla-L-Val) and cyclo(L-Pro-L-Tyr) respectively. These compounds were also found in cell-free supernatants from Proteus mirabilis, Citrobacter freundii and Enterobacter agglomerans [cyclo(DeltaAla-L-Val) only]. Although both DKPs were absent from Pseudomonas fluorescens and Pseudomonas alcaligenes, we isolated, from both pseudomonads, a third DKP, which was chemically characterized as cyclo(L-Phe-L-Pro). Dose-response curves using a LuxR-based AHL biosensor indicated that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) activate the biosensor in a concentration-dependent manner, albeit at much higher concentrations than the natural activator N-(3-oxohexanoyl)-L-homoserine lactone (3-oxo-C6-HSL). Competition studies showed that cyclo(DeltaAla-L-Val), cyclo(L-Pro-L-Tyr) and cyclo(L-Phe-L-Pro) antagonize the 3-oxo-C6-HSL-mediated induction of bioluminescence, suggesting that these DKPs may compete for the same LuxR-binding site. Similarly, DKPs were found to be capable of activating or antagonizing other LuxR-based quorum-sensing systems, such as the N-butanoylhomoserine lactone-dependent swarming motility of Serratia liquefaciens. Although the physiological role of these DKPs has yet to be established, their activity suggests the existence of cross talk among bacterial signalling systems.
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Affiliation(s)
- M T Holden
- School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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Abstract
In Staphylococcus epidermidis and Staphylococcus aureus, a number of cell wall- and cytoplasmic membrane-associated lipoproteins are induced in response to iron starvation. To gain insights into the molecular basis of iron-dependent gene regulation in the staphylococci, we sequenced the DNA upstream of the 3-kb S. epidermidis sitABC operon, which Northern blot analysis indicates is transcriptionally regulated by the growth medium iron content. We identified two DNA sequences which are homologous to elements of the Corynebacterium diphtheriae DtxR regulon, which controls, in response to iron stress, for example, production of diphtheria toxin, siderophore, and a heme oxygenase. Upstream of the sitABC operon and divergently transcribed lies a 645-bp open reading frame (ORF), which codes for a polypeptide of approximately 25 kDa with homology to the DtxR family of metal-dependent repressor proteins. This ORF has been designated SirR (staphylococcal iron regulator repressor). Within the sitABC promoter/operator region, we also located a region of dyad symmetry overlapping the transcriptional start of sitABC which shows high homology to the DtxR operator consensus sequence, suggesting that this region, termed the Sir box, is the SirR-binding site. The SirR protein was overexpressed, purified, and used in DNA mobility shift assays; SirR retarded the migration of a synthetic oligonucleotide based on the Sir box in a metal (Fe2+ or Mn2+)-dependent manner, providing confirmatory evidence that this motif is the SirR-binding site. Furthermore, Southern blot analysis of staphylococcal chromosomal DNA with the synthetic Sir box as a probe confirmed that there are at least five Sir boxes in the S. epidermidis genome and at least three in the genome of S. aureus, suggesting that SirR controls the expression of multiple target genes. Using a monospecific polyclonal antibody raised against SirR to probe Western blots of whole-cell lysates of S. aureus, S. carnosus, S. epidermidis, S. hominis, S. cohnii, S. lugdunensis, and S. haemolyticus, we identified an approximately 25-kDa cross-reactive protein in each of the staphylococcal species examined. Taken together, these data suggest that SirR functions as a divalent metal cation-dependent transcriptional repressor which is widespread among the staphylococci.
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Affiliation(s)
- P J Hill
- Institute of Infections and Immunity, University of Nottingham, Nottingham NG7 2UH, United Kingdom.
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Cockayne A, Hill PJ, Powell NB, Bishop K, Sims C, Williams P. Molecular cloning of a 32-kilodalton lipoprotein component of a novel iron-regulated Staphylococcus epidermidis ABC transporter. Infect Immun 1998; 66:3767-74. [PMID: 9673260 PMCID: PMC108413 DOI: 10.1128/iai.66.8.3767-3774.1998] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Our previous studies identified two iron-regulated cytoplasmic membrane proteins of 32 and 36 kDa expressed by both Staphylococcus epidermidis and Staphylococcus aureus. In this study we show by Triton X-114 phase partitioning and tritiated palmitic acid labelling that these proteins are lipoproteins which are anchored into the cytoplasmic membrane by their lipid-modified N termini. In common with those of some other gram-positive bacteria, these highly immunogenic lipoproteins were released from the bacterial cell into the culture supernatants, with release being promoted by growth of the bacteria under iron-restricted conditions. Immunoelectron microscopy with a monospecific rabbit antiserum to the 32-kDa S. epidermidis lipoprotein showed that the majority of the antigen was distributed throughout the staphylococcal cell wall. Only minor quantities were detected in the cytoplasmic membrane, and exposure of the lipoprotein on the bacterial surface was minimal. A monoclonal antibody raised to the 32-kDa lipoprotein of S. aureus was used in immunoblotting studies to investigate the conservation of this antigen among a variety of staphylococci. The monoclonal antibody reacted with polypeptides of 32 kDa in S. epidermidis and S. aureus and of 40 kDa in Staphylococcus hominis. No reactivity was detected with Staphylococcus lugdunensis, Staphylococcus cohni, or Staphylococcus haemolyticus. The gene encoding the 32-kDa lipoprotein from S. epidermidis has been isolated from a Lambda Zap II genomic DNA library and found to be a component of an iron-regulated operon encoding a novel ABC-type transporter. The operon contains three genes, designated sitA, -B, and -C, encoding an ATPase, a cytoplasmic membrane protein, and the 32-kDa lipoprotein, respectively. SitC shows significant homology both with a number of bacterial adhesins, including FimA of Streptococcus parasanguis and ScaA of Streptococcus gordonii, and with lipoproteins of a recently described family of ABC transporters with proven or putative metal ion transport functions. Although the solute specificity of this novel transporter has not yet been determined, we speculate that it may be involved in either siderophore- or transferrin-mediated iron uptake in S. epidermidis.
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Affiliation(s)
- A Cockayne
- Institute of Infections and Immunity, University of Nottingham, Nottingham NG7 2UH, United Kingdom
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31
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Winson MK, Swift S, Hill PJ, Sims CM, Griesmayr G, Bycroft BW, Williams P, Stewart GS. Engineering the luxCDABE genes from Photorhabdus luminescens to provide a bioluminescent reporter for constitutive and promoter probe plasmids and mini-Tn5 constructs. FEMS Microbiol Lett 1998; 163:193-202. [PMID: 9673022 DOI: 10.1111/j.1574-6968.1998.tb13045.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The luxCDABE operon of Photorhabdus luminescens has been cloned and engineered as an easily mobilisable cassette flanked by sites for commonly used restriction enzymes. Constitutive and promoter probe plasmids utilising the P. luminescens luxCDABE have been constructed using a number of compatible replicons and antibiotic markers. Complementary to these plasmids, a range of promoterless and constitutive luxCDABE mini-Tn5 derivatives has been constructed. The potential of coupling mini-Tn5 luxCDABE promoter probe transposons with automated luminometry and photometry to screen for mutants that exhibit growth phase variation in gene expression is demonstrated.
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Affiliation(s)
- M K Winson
- Food Microbiology Section, School of Biological Sciences, University of Nottingham Leics, USA
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32
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Hill PJ, Hall L, Vinicombe DA, Soper CJ, Setlow P, Waites WM, Denyer S, Stewart GS. Bioluminescence and spores as biological indicators of inimical processes. Soc Appl Bacteriol Symp Ser 1994; 23:129S-134S. [PMID: 8047906 DOI: 10.1111/j.1365-2672.1994.tb04364.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- P J Hill
- Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington, Leicestershire, UK
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Affiliation(s)
- S M Garland
- Department of Microbiology, Royal Women's Hospital, Melbourne
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Abstract
Bioluminescence has emerged in the last decade as a major tool for the study of bacterial adaptation and survival. In addition to the advantages of sensitivity and the real-time, non-invasive nature of this reporter, the imaging potential of using low-light and photon-counting video cameras has been particularly influential in establishing its ascendancy-over more traditional reporter systems. This review provides a reflection of personal activity in this field through applications in Food Microbiology and collaboration with colleagues both in the UK and beyond.
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Affiliation(s)
- P J Hill
- Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington, Leicestershire, UK
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35
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Swift S, Winson MK, Chan PF, Bainton NJ, Birdsall M, Reeves PJ, Rees CE, Chhabra SR, Hill PJ, Throup JP. A novel strategy for the isolation of luxI homologues: evidence for the widespread distribution of a LuxR:LuxI superfamily in enteric bacteria. Mol Microbiol 1993; 10:511-20. [PMID: 7968529 DOI: 10.1111/j.1365-2958.1993.tb00923.x] [Citation(s) in RCA: 171] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The pheromone N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) regulates expression of bioluminescence in the marine bacterium Vibrio fischeri, the production of carbapenem antibiotic in Erwinia carotovora and exoenzymes in both E. carotovora and Pseudomonas aeruginosa. A characteristic feature of this regulatory mechanism in V. fischeri is that it is cell density-dependent, reflecting the need to accumulate sufficient pheromone to trigger the induction of gene expression. Using a lux plasmid-based bioluminescent sensor for OHHL, pheromone production by E. carotovora, Enterobacter agglomerans, Hafnia alvei, Rahnella aquatilis and Serratia marcescens has been demonstrated and shown also to be cell density-dependent. Production of OHHL implies the presence in these bacteria of a gene equivalent to luxI. Chromosomal banks from all five enteric bacteria have yielded clones capable of eliciting OHHL production when expressed in Escherichia coli. The luxI homologue from both E. carotovora (carI) and E. agglomerans (eagI) were characterized at the DNA sequence level and the deduced protein sequences have only 25% identity with the V. fischeri LuxI. Despite this, carI, eagI and luxI are shown to be biologically equivalent. An insertion mutant of eagI demonstrates that this gene is essential for OHHL production in E. agglomerans.
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Affiliation(s)
- S Swift
- Department of Applied Biochemistry and Food Science, Leicestershire, UK
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36
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Abstract
Pseudomonas pseudomallei is the causative agent of melioidosis, a disease being increasingly recognized as an important cause of morbidity and mortality in many regions of the world. An intriguing observation regarding melioidosis is that a significant percentage of patients who develop the disease have preexisting diabetes mellitus. In this regard, we have tested the hypothesis that insulin may modulate the growth of P. pseudomallei. We have demonstrated that insulin markedly inhibits the growth of P. pseudomallei in vitro and in vivo. The growth rate of P. pseudomallei in minimal medium containing human recombinant insulin was significantly lower than that of control cultures containing no insulin. P. pseudomallei grew at an increased rate in serum samples obtained from diabetic rats compared with that in serum samples obtained from control animals. When the insulin level was restored by the addition of human recombinant insulin, the growth rate was reduced to a level similar to that seen in control serum. P. pseudomallei also grew significantly better in insulin-depleted human serum than control human serum. 125I-insulin binding studies demonstrated that P. pseudomallei possesses a specific, high-affinity binding site for human insulin. In in vivo studies, rats made diabetic by streptozotocin injection (80 mg/kg of body weight, intraperitoneally) were significantly more susceptible to P. pseudomallei septicemia than control rats. Thus, it appears that serum insulin levels may play a significant role in modulating the pathogenesis of P. pseudomallei septicemic infections.
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Affiliation(s)
- D E Woods
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, University of Calgary Health Sciences Centre, Alberta, Canada
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Hill PJ, Stewart GS, Stanley PE. Bioluminescence and chemiluminescence literature. Luciferase reporter genes--lux and luc. Part 2. J Biolumin Chemilumin 1993; 8:267-91. [PMID: 8237470 DOI: 10.1002/bio.1170080507] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The following references encompass a review of recent literature where the in vivo expression of eukaryotic and/or prokaryotic luciferases provide for sensitive reporters of cellular activity. The list is subdivided into prokaryotic and eukaryotic applications. We have included the uses of luciferases in elucidating the control of gene expression or for monitoring cell viability. We have not included papers cited by Stanley and Stewart (J Biolumin Chemilumin 1990; 5:141-52) nor have we included papers on the structure and regulation of luciferases as this now substantial literature will be the subject of a future review. References cited in both this review and previous ones are referred to by the number assigned to them in the earlier review.
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Hill PJ, Rees CE, Winson MK, Stewart GS. The application of lux genes. Biotechnol Appl Biochem 1993; 17:3-14. [PMID: 8439401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- P J Hill
- University of Nottingham, Faculty of Agricultural and Food Sciences, Department of Applied Biochemistry and Food Science, Leicestershire, U.K
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Abstract
The polymerase chain reaction (PCR) has been used to detect Listeria monocytogenes in whole milk at a level of 0.1 cfu per 30 ml. This high degree of sensitivity has been achieved following enzymatic digestion, polysulphonone membrane filtration and amplification of a nucleotide sequence within the promoter region of hlyA. Key elements of the procedure are the absence of enrichment culture and a complete solubilization of the membrane filter, ensuring total nucleic acid recovery. The simplicity of the protocol coupled with high sample volumes and exquisite sensitivity extends the relevance of PCR within food and environmental microbiology.
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Affiliation(s)
- M A Starbuck
- University of Nottingham, Faculty of Agriculture and Food Sciences, Department of Applied Biochemistry and Food Science, Loughborough, Leics, UK
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40
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Affiliation(s)
- P J Hill
- Department of Applied Biochemistry and Food Science, University of Nottingham, Sutton Bonington, UK
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Bainton NJ, Bycroft BW, Chhabra SR, Stead P, Gledhill L, Hill PJ, Rees CE, Winson MK, Salmond GP, Stewart GS. A general role for the lux autoinducer in bacterial cell signalling: control of antibiotic biosynthesis in Erwinia. Gene X 1992; 116:87-91. [PMID: 1628848 DOI: 10.1016/0378-1119(92)90633-z] [Citation(s) in RCA: 196] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Micro-organisms have evolved complex and diverse mechanisms to sense environmental changes. Activation of a sensory mechanism typically leads to alterations in gene expression facilitating an adaptive response. This may take several forms, but many are mediated by response-regulator proteins. The luxR-encoded protein (LuxR) has previously been characterised as a member of the response-regulator superfamily and is known to respond to the small diffusible autoinducer signal molecule N-(beta-ketocaproyl) homoserine lactone (KHL). Observed previously in only a few marine bacteria, we now report that KHL is in fact produced by a diverse group of terrestrial bacteria. In one of these (Erwinia carotovora), we show that it acts as a molecular control signal for the expression of genes controlling carbapenem antibiotic biosynthesis. This represents the first substantive evidence to support the previous postulate that the lux autoinducer, KHL, is widely involved in bacterial signalling.
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Affiliation(s)
- N J Bainton
- Department of Pharmaceutical Sciences, University of Nottingham, University Park, U.K
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Jacobs M, Hill PJ, Stewart GS. Highly bioluminescent Bacillus subtilis obtained through high-level expression of a luxAB fusion gene. Mol Gen Genet 1991; 230:251-6. [PMID: 1745233 DOI: 10.1007/bf00290675] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Bioluminescence levels comparable to those achievable in Escherichia coli have yet to be obtained from luxAB expression in gram-positive bacteria. In this communication we describe the gene engineering required to generate a highly bioluminescent derivative of Bacillus subtilis. The combination of a powerful promoter, Pxyn, a fusion derivative of luxAB from Vibrio harveyi and translational coupling have overcome the previously reported limitations in luxAB expression. The implications for highly bioluminescent gram-positive organisms are discussed.
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Affiliation(s)
- M Jacobs
- Department of Microbiology, Technical University of Denmark, Lyngby
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Hill PJ, Swift S, Stewart GS. PCR based gene engineering of the Vibrio harveyi lux operon and the Escherichia coli trp operon provides for biochemically functional native and fused gene products. Mol Gen Genet 1991; 226:41-8. [PMID: 2034229 DOI: 10.1007/bf00273585] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The polymerase chain reaction (PCR) was applied to clone the luxA and luxB genes from Vibrio harveyi, and the trp poL (promoter operator leader) region and the trpB and trpA genes from Escherichia coli. PCR-derived luxA/B and trpB/A genes were shown to express bacterial luciferase and tryptophan synthase respectively, when introduced into E. coli on a plasmid cloning vehicle. The trp poL was used successfully to control the expression of lac alpha, luxAB, trpB and trpA. PCR was also used to construct a functional luxAB translational fusion protein. Primers for this were designed to facilitate precise gene fusion and to provide a silent mutation within an EcoRI site in the luxB gene. Production of functional genes was verified in vitro and in vivo using polyacrylamide gel electrophoresis (PAGE) analysis of transcription-translation products and crude cell extracts, and by monitoring enzyme activity.
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Affiliation(s)
- P J Hill
- Department of Applied Biochemistry and Food Science, University of Nottingham School of Agriculture, Sutton Bonington, Leicestershire, UK
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Trent RJ, Mickleson KN, Wilkinson T, Yakas J, Dixon MW, Hill PJ, Kronenberg H. Globin genes in Polynesians have many rearrangements including a recently described gamma gamma gamma gamma/. Am J Hum Genet 1986; 39:350-60. [PMID: 3766541 PMCID: PMC1683950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rearrangements involving genes of the alpha- and beta-globin loci were frequently detected in DNA from Polynesians. A founder effect and genetic drift occurring 2,000-3,000 years ago as Polynesians migrated eastward across the Pacific is proposed as the likely mechanism for these genetic changes that include deletions or additions of alpha-, gamma-, and zeta-globin genes and an unusual restriction fragment length polymorphism (RFLP) associated with the zeta gene. Preliminary data show different frequencies for gene rearrangements between island groups. Further study of these differences should provide additional information on the prehistory of Polynesians.
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Mickleson KN, Dixon MW, Hill PJ, Bluck R, Eales M, Rutherford J, Yakas J, Trent RJ. Influence of alpha thalassaemia on haematological parameters in Polynesian patients. N Z Med J 1985; 98:1036-8. [PMID: 3867007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA mapping of the alpha globin gene cluster in cord blood from Polynesians has shown an increased frequency of alpha thalassaemia and triplicated alpha genes. Reduced levels of haemoglobin, mean corpuscular haemoglobin or mean corpuscular volume in these neonates may indicate alpha thalassaemia. Recognition of this will avoid unnecessary haematological investigations and iron supplementation.
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Taylor PJ, Cumming DC, Hill PJ. Significance of intrauterine adhesions detected hysteroscopically in eumenorrheic infertile women and role of antecedent curettage in their formation. Am J Obstet Gynecol 1981; 139:239-42. [PMID: 7468688 DOI: 10.1016/0002-9378(81)90001-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The increasing use of hysteroscopy as a diagnostic tool in the infertile woman has shown that intrauterine adhesions are of more concern, especially in eumenorrheic women, than previously was recognized. Their significance is not yet clear. This study was designed to compare the incidence of such lesions detected hysteroscopically in 235 women with otherwise unexplained infertility with their incidence in a group of 31 potentially fertile women. The outcome after treatment was recorded. The effect of curettage in the production of these adhesions was examined. The incidence of adhesions in the infertile group was considerably greater than in the potentially fertile group (p less than 0.05). A 50% pregnancy rate was achieved by lysis of adhesions. An antecedent history of curettage was associated with a significantly higher incidence of adhesion formation than that found in noncuretted patients (p less than 0.0005).
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Hill PJ. Reversals in reading: are they abnormal? Am J Optom Physiol Opt 1980; 57:162-5. [PMID: 7386577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In a study of 257 children in kindergarten through fourth grade, in a Michigan public school, 38% were identified and referred to a special class as having problems in reading and writing or reversing letters and words. The percentage of children having these problems decreased regularly with age; however, the proportion of children exhibiting reversals among those referred was fairly constant through the second grade, after which it became negligible. Analysis indicates that when children in the first several grades in public school learn to read from regular classroom instruction, letter and word reversals tend to disappear. For young children, reversals in reading appear to be normal errors associated with learning to read.
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Hill PJ. Visual motor perceptual performance as compared with tests of recognition. Am J Optom Arch Am Acad Optom 1970; 47:469-73. [PMID: 5269135 DOI: 10.1097/00006324-197006000-00007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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49
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Hill JF, Hill PJ. Clinical comparison of the tonomat applanation tonometer with the Mackay-Marg electronic tonometer. Am J Optom Arch Am Acad Optom 1969; 46:797-800. [PMID: 5259640 DOI: 10.1097/00006324-196910000-00011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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