1
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Attrill EL, Łapińska U, Westra ER, Harding SV, Pagliara S. Slow growing bacteria survive bacteriophage in isolation. ISME Commun 2023; 3:95. [PMID: 37684358 PMCID: PMC10491631 DOI: 10.1038/s43705-023-00299-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 08/09/2023] [Accepted: 08/14/2023] [Indexed: 09/10/2023]
Abstract
The interactions between bacteria and bacteriophage have important roles in the global ecosystem; in turn changes in environmental parameters affect the interactions between bacteria and phage. However, there is a lack of knowledge on whether clonal bacterial populations harbour different phenotypes that respond to phage in distinct ways and whether the abundance of such phenotypes within bacterial populations is affected by variations in environmental parameters. Here we study the impact of variations in nutrient availability, bacterial growth rate and phage abundance on the interactions between the phage T4 and individual Escherichia coli cells confined in spatial refuges. Surprisingly, we found that fast growing bacteria survive together with all of their clonal kin cells, whereas slow growing bacteria survive in isolation. We also discovered that the number of bacteria that survive in isolation decreases at increasing phage doses possibly due to lysis inhibition in the presence of secondary adsorptions. We further show that these changes in the phenotypic composition of the E. coli population have important consequences on the bacterial and phage population dynamics and should therefore be considered when investigating bacteria-phage interactions in ecological, health or food production settings in structured environments.
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Affiliation(s)
- Erin L Attrill
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK
| | - Edze R Westra
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, UK
| | - Sarah V Harding
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
- Department of Respiratory Sciences, University of Leicester, Leicester, UK
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, UK.
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2
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Zhang B, Phetsang W, Stone MRL, Kc S, Butler MS, Cooper MA, Elliott AG, Łapińska U, Voliotis M, Tsaneva-Atanasova K, Pagliara S, Blaskovich MAT. Synthesis of vancomycin fluorescent probes that retain antimicrobial activity, identify Gram-positive bacteria, and detect Gram-negative outer membrane damage. Commun Biol 2023; 6:409. [PMID: 37055536 PMCID: PMC10102067 DOI: 10.1038/s42003-023-04745-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 03/22/2023] [Indexed: 04/15/2023] Open
Abstract
Antimicrobial resistance is an urgent threat to human health, and new antibacterial drugs are desperately needed, as are research tools to aid in their discovery and development. Vancomycin is a glycopeptide antibiotic that is widely used for the treatment of Gram-positive infections, such as life-threatening systemic diseases caused by methicillin-resistant Staphylococcus aureus (MRSA). Here we demonstrate that modification of vancomycin by introduction of an azide substituent provides a versatile intermediate that can undergo copper-catalysed azide-alkyne cycloaddition (CuAAC) reaction with various alkynes to readily prepare vancomycin fluorescent probes. We describe the facile synthesis of three probes that retain similar antibacterial profiles to the parent vancomycin antibiotic. We demonstrate the versatility of these probes for the detection and visualisation of Gram-positive bacteria by a range of methods, including plate reader quantification, flow cytometry analysis, high-resolution microscopy imaging, and single cell microfluidics analysis. In parallel, we demonstrate their utility in measuring outer-membrane permeabilisation of Gram-negative bacteria. The probes are useful tools that may facilitate detection of infections and development of new antibiotics.
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Affiliation(s)
- Bing Zhang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Wanida Phetsang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Sanjaya Kc
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Mark S Butler
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Matthew A Cooper
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Alysha G Elliott
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Margaritis Voliotis
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
- EPSRC Hub for Quantitative Modelling in Healthcare, University of Exeter, Exeter, EX4 4QJ, UK
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 105 Acad. G. Bonchev Street, 1113, Sofia, Bulgaria
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, 4072, Australia.
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3
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Łapińska U, Glover G, Kahveci Z, Irwin NAT, Milner DS, Tourte M, Albers SV, Santoro AE, Richards TA, Pagliara S. Systematic comparison of unilamellar vesicles reveals that archaeal core lipid membranes are more permeable than bacterial membranes. PLoS Biol 2023; 21:e3002048. [PMID: 37014915 PMCID: PMC10072491 DOI: 10.1371/journal.pbio.3002048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 02/22/2023] [Indexed: 04/05/2023] Open
Abstract
One of the deepest branches in the tree of life separates the Archaea from the Bacteria. These prokaryotic groups have distinct cellular systems including fundamentally different phospholipid membrane bilayers. This dichotomy has been termed the lipid divide and possibly bestows different biophysical and biochemical characteristics on each cell type. Classic experiments suggest that bacterial membranes (formed from lipids extracted from Escherichia coli, for example) show permeability to key metabolites comparable to archaeal membranes (formed from lipids extracted from Halobacterium salinarum), yet systematic analyses based on direct measurements of membrane permeability are absent. Here, we develop a new approach for assessing the membrane permeability of approximately 10 μm unilamellar vesicles, consisting of an aqueous medium enclosed by a single lipid bilayer. Comparing the permeability of 18 metabolites demonstrates that diether glycerol-1-phosphate lipids with methyl branches, often the most abundant membrane lipids of sampled archaea, are permeable to a wide range of compounds useful for core metabolic networks, including amino acids, sugars, and nucleobases. Permeability is significantly lower in diester glycerol-3-phosphate lipids without methyl branches, the common building block of bacterial membranes. To identify the membrane characteristics that determine permeability, we use this experimental platform to test a variety of lipid forms bearing a diversity of intermediate characteristics. We found that increased membrane permeability is dependent on both the methyl branches on the lipid tails and the ether bond between the tails and the head group, both of which are present on the archaeal phospholipids. These permeability differences must have had profound effects on the cell physiology and proteome evolution of early prokaryotic forms. To explore this further, we compare the abundance and distribution of transmembrane transporter-encoding protein families present on genomes sampled from across the prokaryotic tree of life. These data demonstrate that archaea tend to have a reduced repertoire of transporter gene families, consistent with increased membrane permeation. These results demonstrate that the lipid divide demarcates a clear difference in permeability function with implications for understanding some of the earliest transitions in cell origins and evolution.
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Affiliation(s)
- Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Georgina Glover
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Zehra Kahveci
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Nicholas A T Irwin
- Merton College, University of Oxford, Oxford, United Kingdom
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - David S Milner
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Maxime Tourte
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Freiburg, Germany
| | - Alyson E Santoro
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California, United States of America
| | | | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
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4
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Łapińska U, Voliotis M, Lee KK, Campey A, Stone MRL, Tuck B, Phetsang W, Zhang B, Tsaneva-Atanasova K, Blaskovich MAT, Pagliara S. Fast bacterial growth reduces antibiotic accumulation and efficacy. eLife 2022; 11:74062. [PMID: 35670099 PMCID: PMC9173744 DOI: 10.7554/elife.74062] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 05/08/2022] [Indexed: 12/11/2022] Open
Abstract
Phenotypic variations between individual microbial cells play a key role in the resistance of microbial pathogens to pharmacotherapies. Nevertheless, little is known about cell individuality in antibiotic accumulation. Here, we hypothesise that phenotypic diversification can be driven by fundamental cell-to-cell differences in drug transport rates. To test this hypothesis, we employed microfluidics-based single-cell microscopy, libraries of fluorescent antibiotic probes and mathematical modelling. This approach allowed us to rapidly identify phenotypic variants that avoid antibiotic accumulation within populations of Escherichia coli, Pseudomonas aeruginosa, Burkholderia cenocepacia, and Staphylococcus aureus. Crucially, we found that fast growing phenotypic variants avoid macrolide accumulation and survive treatment without genetic mutations. These findings are in contrast with the current consensus that cellular dormancy and slow metabolism underlie bacterial survival to antibiotics. Our results also show that fast growing variants display significantly higher expression of ribosomal promoters before drug treatment compared to slow growing variants. Drug-free active ribosomes facilitate essential cellular processes in these fast-growing variants, including efflux that can reduce macrolide accumulation. We used this new knowledge to eradicate variants that displayed low antibiotic accumulation through the chemical manipulation of their outer membrane inspiring new avenues to overcome current antibiotic treatment failures.
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Affiliation(s)
- Urszula Łapińska
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Margaritis Voliotis
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Department of Mathematics, University of ExeterExeterUnited Kingdom
| | - Ka Kiu Lee
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Adrian Campey
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New JerseyPiscatawayUnited States
| | - Brandon Tuck
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
| | - Wanida Phetsang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Bing Zhang
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Department of Mathematics, University of ExeterExeterUnited Kingdom
- EPSRC Hub for Quantitative Modelling in Healthcare, University of ExeterExeterUnited Kingdom
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of SciencesSofiaBulgaria
| | - Mark AT Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of QueenslandBrisbaneAustralia
| | - Stefano Pagliara
- Living Systems Institute, University of ExeterExeterUnited Kingdom
- Biosciences, University of ExeterExeterUnited Kingdom
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5
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Glover G, Voliotis M, Łapińska U, Invergo BM, Soanes D, O'Neill P, Moore K, Nikolic N, Petrov PG, Milner DS, Roy S, Heesom K, Richards TA, Tsaneva-Atanasova K, Pagliara S. Nutrient and salt depletion synergistically boosts glucose metabolism in individual Escherichia coli cells. Commun Biol 2022; 5:385. [PMID: 35444215 PMCID: PMC9021252 DOI: 10.1038/s42003-022-03336-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/30/2022] [Indexed: 12/16/2022] Open
Abstract
The interaction between a cell and its environment shapes fundamental intracellular processes such as cellular metabolism. In most cases growth rate is treated as a proximal metric for understanding the cellular metabolic status. However, changes in growth rate might not reflect metabolic variations in individuals responding to environmental fluctuations. Here we use single-cell microfluidics-microscopy combined with transcriptomics, proteomics and mathematical modelling to quantify the accumulation of glucose within Escherichia coli cells. In contrast to the current consensus, we reveal that environmental conditions which are comparatively unfavourable for growth, where both nutrients and salinity are depleted, increase glucose accumulation rates in individual bacteria and population subsets. We find that these changes in metabolic function are underpinned by variations at the translational and posttranslational level but not at the transcriptional level and are not dictated by changes in cell size. The metabolic response-characteristics identified greatly advance our fundamental understanding of the interactions between bacteria and their environment and have important ramifications when investigating cellular processes where salinity plays an important role.
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Affiliation(s)
- Georgina Glover
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - Margaritis Voliotis
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Brandon M Invergo
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK
| | - Darren Soanes
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Paul O'Neill
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Karen Moore
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Nela Nikolic
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - Peter G Petrov
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - David S Milner
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Sumita Roy
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Kate Heesom
- University of Bristol Proteomics Facility, University Walk, Bristol, BS8 1TD, UK
| | - Thomas A Richards
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 105 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK.
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6
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Conners R, McLaren M, Łapińska U, Sanders K, Stone MRL, Blaskovich MAT, Pagliara S, Daum B, Rakonjac J, Gold VAM. CryoEM structure of the outer membrane secretin channel pIV from the f1 filamentous bacteriophage. Nat Commun 2021; 12:6316. [PMID: 34728631 PMCID: PMC8563730 DOI: 10.1038/s41467-021-26610-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 11/09/2022] Open
Abstract
The Ff family of filamentous bacteriophages infect gram-negative bacteria, but do not cause lysis of their host cell. Instead, new virions are extruded via the phage-encoded pIV protein, which has homology with bacterial secretins. Here, we determine the structure of pIV from the f1 filamentous bacteriophage at 2.7 Å resolution by cryo-electron microscopy, the first near-atomic structure of a phage secretin. Fifteen f1 pIV subunits assemble to form a gated channel in the bacterial outer membrane, with associated soluble domains projecting into the periplasm. We model channel opening and propose a mechanism for phage egress. By single-cell microfluidics experiments, we demonstrate the potential for secretins such as pIV to be used as adjuvants to increase the uptake and efficacy of antibiotics in bacteria. Finally, we compare the f1 pIV structure to its homologues to reveal similarities and differences between phage and bacterial secretins.
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Affiliation(s)
- Rebecca Conners
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Mathew McLaren
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Kelly Sanders
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Bertram Daum
- Living Systems Institute, University of Exeter, Exeter, UK
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK
| | - Jasna Rakonjac
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Vicki A M Gold
- Living Systems Institute, University of Exeter, Exeter, UK.
- College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Exeter, UK.
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7
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Attrill EL, Claydon R, Łapińska U, Recker M, Meaden S, Brown AT, Westra ER, Harding SV, Pagliara S. Individual bacteria in structured environments rely on phenotypic resistance to phage. PLoS Biol 2021; 19:e3001406. [PMID: 34637438 PMCID: PMC8509860 DOI: 10.1371/journal.pbio.3001406] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 09/02/2021] [Indexed: 12/12/2022] Open
Abstract
Bacteriophages represent an avenue to overcome the current antibiotic resistance crisis, but evolution of genetic resistance to phages remains a concern. In vitro, bacteria evolve genetic resistance, preventing phage adsorption or degrading phage DNA. In natural environments, evolved resistance is lower possibly because the spatial heterogeneity within biofilms, microcolonies, or wall populations favours phenotypic survival to lytic phages. However, it is also possible that the persistence of genetically sensitive bacteria is due to less efficient phage amplification in natural environments, the existence of refuges where bacteria can hide, and a reduced spread of resistant genotypes. Here, we monitor the interactions between individual planktonic bacteria in isolation in ephemeral refuges and bacteriophage by tracking the survival of individual cells. We find that in these transient spatial refuges, phenotypic resistance due to reduced expression of the phage receptor is a key determinant of bacterial survival. This survival strategy is in contrast with the emergence of genetic resistance in the absence of ephemeral refuges in well-mixed environments. Predictions generated via a mathematical modelling framework to track bacterial response to phages reveal that the presence of spatial refuges leads to fundamentally different population dynamics that should be considered in order to predict and manipulate the evolutionary and ecological dynamics of bacteria–phage interactions in naturally structured environments. Bacteriophages represent a promising avenue to overcome the current antibiotic resistance crisis, but evolution of phage resistance remains a concern. This study shows that in the presence of spatial refuges, genetic resistance to phage is less of a problem than commonly assumed, but the persistence of genetically susceptible bacteria suggests that eradicating bacterial pathogens from structured environments may require combined phage-antibiotic therapies.
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Affiliation(s)
- Erin L. Attrill
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Rory Claydon
- SUPA, School of Physics and Astronomy, The University of Edinburgh, United Kingdom
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn, United Kingdom
| | - Sean Meaden
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, United Kingdom
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Aidan T. Brown
- SUPA, School of Physics and Astronomy, The University of Edinburgh, United Kingdom
| | - Edze R. Westra
- Environment and Sustainability Institute and Biosciences, University of Exeter, Penryn, United Kingdom
| | - Sarah V. Harding
- Defence Science and Technology Laboratory, Porton Down, Salisbury, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Exeter, United Kingdom
- * E-mail:
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8
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Goode O, Smith A, Łapińska U, Bamford R, Kahveci Z, Glover G, Attrill E, Carr A, Metz J, Pagliara S. Heterologous Protein Expression Favors the Formation of Protein Aggregates in Persister and Viable but Nonculturable Bacteria. ACS Infect Dis 2021; 7:1848-1858. [PMID: 34000805 DOI: 10.1021/acsinfecdis.1c00154] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Environmental and intracellular stresses can perturb protein homeostasis and trigger the formation and accumulation of protein aggregates. It has been recently suggested that the level of protein aggregates accumulated in bacteria correlates with the frequency of persister and viable but nonculturable cells that transiently survive treatment with multiple antibiotics. However, these findings have often been obtained employing fluorescent reporter strains. This enforced heterologous protein expression facilitates the visualization of protein aggregates but could also trigger the formation and accumulation of protein aggregates. Using microfluidics-based single-cell microscopy and a library of green fluorescent protein reporter strains, we show that heterologous protein expression favors the formation of protein aggregates. We found that persister and viable but nonculturable bacteria surviving treatment with antibiotics are more likely to contain protein aggregates and downregulate the expression of heterologous proteins. Our data also suggest that such aggregates are more basic with respect to the rest of the cell. These findings provide evidence for a strong link between heterologous protein expression, protein aggregation, intracellular pH, and phenotypic survival to antibiotics, suggesting that antibiotic treatments against persister and viable but nonculturable cells could be developed by modulating protein aggregation and pH regulation.
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Affiliation(s)
- Olivia Goode
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Ashley Smith
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Urszula Łapińska
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Rosemary Bamford
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Zehra Kahveci
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Georgina Glover
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Erin Attrill
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Alice Carr
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Jeremy Metz
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and Biosciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom
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9
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Stone MRL, Łapińska U, Pagliara S, Masi M, Blanchfield JT, Cooper MA, Blaskovich MAT. Fluorescent macrolide probes - synthesis and use in evaluation of bacterial resistance. RSC Chem Biol 2020; 1:395-404. [PMID: 34458770 PMCID: PMC8341779 DOI: 10.1039/d0cb00118j] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/28/2020] [Indexed: 12/19/2022] Open
Abstract
The emerging crisis of antibiotic resistance requires a multi-pronged approach in order to avert the onset of a post-antibiotic age. Studies of antibiotic uptake and localisation in live cells may inform the design of improved drugs and help develop a better understanding of bacterial resistance and persistence. To facilitate this research, we have synthesised fluorescent derivatives of the macrolide antibiotic erythromycin. These analogues exhibit a similar spectrum of antibiotic activity to the parent drug and are capable of labelling both Gram-positive and -negative bacteria for microscopy. The probes localise intracellularly, with uptake in Gram-negative bacteria dependent on the level of efflux pump activity. A plate-based assay established to quantify bacterial labelling and localisation demonstrated that the probes were taken up by both susceptible and resistant bacteria. Significant intra-strain and -species differences were observed in these preliminary studies. In order to examine uptake in real-time, the probe was used in single-cell microfluidic microscopy, revealing previously unseen heterogeneity of uptake in populations of susceptible bacteria. These studies illustrate the potential of fluorescent macrolide probes to characterise and explore drug uptake and efflux in bacteria. Macrolide fluorescent probes illuminate the interactions between antibiotics and bacteria, providing new insight into mechanisms of resistance.![]()
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Affiliation(s)
- M Rhia L Stone
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland 306 Carmody Road St Lucia 4072 Brisbane Australia
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter Exeter EX4 4QD UK
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter Exeter EX4 4QD UK
| | - Muriel Masi
- Université Paris-Saclay, CEA, CNRS Institute for Integrative Biology of the Cell (I2BC) 911198 Gif-sur-Yvette France
| | - Joanne T Blanchfield
- School of Chemistry and Molecular Biosciences, The University of Queensland 68 Cooper Road St Lucia 4072 Brisbane Australia
| | - Matthew A Cooper
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland 306 Carmody Road St Lucia 4072 Brisbane Australia
| | - Mark A T Blaskovich
- Centre for Superbug Solutions, Institute for Molecular Bioscience, The University of Queensland 306 Carmody Road St Lucia 4072 Brisbane Australia
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10
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Kepiro IE, Marzuoli I, Hammond K, Ba X, Lewis H, Shaw M, Gunnoo SB, De Santis E, Łapińska U, Pagliara S, Holmes MA, Lorenz CD, Hoogenboom BW, Fraternali F, Ryadnov MG. Engineering Chirally Blind Protein Pseudocapsids into Antibacterial Persisters. ACS Nano 2020; 14:1609-1622. [PMID: 31794180 DOI: 10.1021/acsnano.9b06814] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Antimicrobial resistance stimulates the search for antimicrobial forms that may be less subject to acquired resistance. Here we report a conceptual design of protein pseudocapsids exhibiting a broad spectrum of antimicrobial activities. Unlike conventional antibiotics, these agents are effective against phenotypic bacterial variants, while clearing "superbugs" in vivo without toxicity. The design adopts an icosahedral architecture that is polymorphic in size, but not in shape, and that is available in both l and d epimeric forms. Using a combination of nanoscale and single-cell imaging we demonstrate that such pseudocapsids inflict rapid and irreparable damage to bacterial cells. In phospholipid membranes they rapidly convert into nanopores, which remain confined to the binding positions of individual pseudocapsids. This mechanism ensures precisely delivered influxes of high antimicrobial doses, rendering the design a versatile platform for engineering structurally diverse and functionally persistent antimicrobial agents.
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Affiliation(s)
- Ibolya E Kepiro
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
| | - Irene Marzuoli
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
- Randall Centre for Cell and Molecular Biophysics , King's College London , London , SE1 1UL , U.K
| | - Katharine Hammond
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
- Department of Physics and Astronomy , University College London , London , WC1E 6BT , U.K
- London Centre for Nanotechnology , University College London , London , WC1H 0AH , U.K
| | - Xiaoliang Ba
- Department of Veterinary Medicine , University of Cambridge , Cambridge , CB3 0ES , U.K
| | - Helen Lewis
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
| | - Michael Shaw
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
- Department of Computer Science , University College London , London , WC1 6BT , U.K
| | - Smita B Gunnoo
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
| | - Emiliana De Santis
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
| | - Urszula Łapińska
- Living Systems Institute , University of Exeter , Exeter , EX4 4QD , U.K
| | - Stefano Pagliara
- Living Systems Institute , University of Exeter , Exeter , EX4 4QD , U.K
| | - Mark A Holmes
- Department of Veterinary Medicine , University of Cambridge , Cambridge , CB3 0ES , U.K
| | - Christian D Lorenz
- Department of Physics , King's College London , Strand Lane , London , WC2R 2LS , U.K
| | - Bart W Hoogenboom
- Department of Physics and Astronomy , University College London , London , WC1E 6BT , U.K
- London Centre for Nanotechnology , University College London , London , WC1H 0AH , U.K
| | - Franca Fraternali
- Randall Centre for Cell and Molecular Biophysics , King's College London , London , SE1 1UL , U.K
| | - Maxim G Ryadnov
- National Physical Laboratory , Hampton Road , Teddington , TW11 0LW , U.K
- Department of Physics , King's College London , Strand Lane , London , WC2R 2LS , U.K
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11
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James-Pemberton P, Łapińska U, Helliwell M, Olkhov RV, Hedaux OJ, Hyde CJ, Shaw AM. Accuracy and precision analysis for a biophotonic assay of C-reactive protein. Analyst 2020; 145:2751-2757. [PMID: 32091040 DOI: 10.1039/c9an02516b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A multiplexed biophotonic assay platform has been developed using the localised particle plasmon in gold nanoparticles assembled in an array and functionalised for two assays: total IgG and C-reactive protein (CRP). A protein A/G (PAG) assay, calibrated with a NIST reference material, shows a maximum surface coverage of θmax = 7.13 ± 0.19 mRIU, equivalent to 1.5 ng mm-2 of F(ab)-presenting antibody. The CRP capture antibody has an equivalent surface binding density of θmax = 2.95 ± 0.41 mRIU indicating a 41% capture antibody availability. Free PAG binding to the functionalised anti-CRP surface shows that only 47 ± 3% of CRP capture antibodies are correctly presenting Fab regions for antigen capture. The accuracy and precision of the CRP sensor assay was assessed with 54 blood samples containing spiked CRP in the range 2-160 mg L-1. The mean accuracy was 0.42 mg L-1 with Confidence Interval (CI) at 95% from -14.7 to 13.8 mg L-1 and the precision had a Coefficient of Variation (CV) of 10.6% with 95% CI 0.9%-20.2%. These biophotonic platform performance metrics indicate a CRP assay with 2-160 mg L-1 dynamic range, performed in 8 minutes from 5 μL of whole blood without sample preparation.
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12
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Łapińska U, Glover G, Capilla-Lasheras P, Young AJ, Pagliara S. Bacterial ageing in the absence of external stressors. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180442. [PMID: 31587633 PMCID: PMC6792439 DOI: 10.1098/rstb.2018.0442] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2019] [Indexed: 12/03/2022] Open
Abstract
Evidence of ageing in the bacterium Escherichia coli was a landmark finding in senescence research, as it suggested that even organisms with morphologically symmetrical fission may have evolved strategies to permit damage accumulation. However, recent work has suggested that ageing is only detectable in this organism in the presence of extrinsic stressors, such as the fluorescent proteins and strong light sources typically used to excite them. Here we combine microfluidics with brightfield microscopy to provide evidence of ageing in E. coli in the absence of these stressors. We report (i) that the doubling time of the lineage of cells that consistently inherits the 'maternal old pole' progressively increases with successive rounds of cell division until it reaches an apparent asymptote, and (ii) that the parental cell divides asymmetrically, with the old pole daughter showing a longer doubling time and slower glucose accumulation than the new pole daughter. Notably, these patterns arise without the progressive accumulation or asymmetric partitioning of observable misfolded-protein aggregates, phenomena previously hypothesized to cause the ageing phenotype. Our findings suggest that ageing is part of the naturally occurring ecologically-relevant phenotype of this bacterium and highlight the importance of alternative mechanisms of damage accumulation in this context. This article is part of a discussion meeting issue 'Single cell ecology'.
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Affiliation(s)
- Urszula Łapińska
- Biosciences, University of Exeter, Exeter, Devon EX4 4QD, UK
- Living Systems Institute, University of Exeter, Exeter, Devon EX4 4QD, UK
| | - Georgina Glover
- Biosciences, University of Exeter, Exeter, Devon EX4 4QD, UK
- Living Systems Institute, University of Exeter, Exeter, Devon EX4 4QD, UK
| | - Pablo Capilla-Lasheras
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Andrew J. Young
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Stefano Pagliara
- Biosciences, University of Exeter, Exeter, Devon EX4 4QD, UK
- Living Systems Institute, University of Exeter, Exeter, Devon EX4 4QD, UK
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13
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Scheidt T, Łapińska U, Kumita JR, Whiten DR, Klenerman D, Wilson MR, Cohen SIA, Linse S, Vendruscolo M, Dobson CM, Knowles TPJ, Arosio P. Secondary nucleation and elongation occur at different sites on Alzheimer's amyloid-β aggregates. Sci Adv 2019; 5:eaau3112. [PMID: 31001578 PMCID: PMC6469941 DOI: 10.1126/sciadv.aau3112] [Citation(s) in RCA: 105] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 02/27/2019] [Indexed: 05/22/2023]
Abstract
The aggregates of the Aβ peptide associated with Alzheimer's disease are able to both grow in size as well as generate, through secondary nucleation, new small oligomeric species, that are major cytotoxins associated with neuronal death. Despite the importance of these amyloid fibril-dependent processes, their structural and molecular underpinnings have remained challenging to elucidate. Here, we consider two molecular chaperones: the Brichos domain, which suppresses specifically secondary nucleation processes, and clusterin which our results show is capable of inhibiting, specifically, the elongation of Aβ fibrils at remarkably low substoichiometric ratios. Microfluidic diffusional sizing measurements demonstrate that this inhibition originates from interactions of clusterin with fibril ends with high affinity. Kinetic experiments in the presence of both molecular chaperones reveal that their inhibitory effects are additive and noncooperative, thereby indicating that the reactive sites associated with the formation of new aggregates and the growth of existing aggregates are distinct.
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Affiliation(s)
- Tom Scheidt
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Urszula Łapińska
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Janet R. Kumita
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Daniel R. Whiten
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - David Klenerman
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Mark R. Wilson
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
| | - Samuel I. A. Cohen
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, Box 124, SE221 00 Lund, Sweden
| | - Michele Vendruscolo
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Christopher M. Dobson
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Tuomas P. J. Knowles
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
- Corresponding author. (T.P.J.K.); (P.A.)
| | - Paolo Arosio
- Centre for Misfolding Diseases, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg, 8093 Zurich, Switzerland
- Corresponding author. (T.P.J.K.); (P.A.)
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14
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Vetri V, Piccirilli F, Krausser J, Buscarino G, Łapińska U, Vestergaard B, Zaccone A, Foderà V. Ethanol Controls the Self-Assembly and Mesoscopic Properties of Human Insulin Amyloid Spherulites. J Phys Chem B 2018; 122:3101-3112. [DOI: 10.1021/acs.jpcb.8b01779] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Valeria Vetri
- Dipartimento di Fisica e Chimica and Advanced Technologies Network Center (ATEN), Università degli Studi di Palermo, Viale delle Scienze ed.18, Palermo 90128, Italy
| | - Federica Piccirilli
- Dipartimento di Fisica e Chimica and Advanced Technologies Network Center (ATEN), Università degli Studi di Palermo, Viale delle Scienze ed.18, Palermo 90128, Italy
| | - Johannes Krausser
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, U.K
| | - Gianpiero Buscarino
- Dipartimento di Fisica e Chimica and Advanced Technologies Network Center (ATEN), Università degli Studi di Palermo, Viale delle Scienze ed.18, Palermo 90128, Italy
| | - Urszula Łapińska
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | | | - Alessio Zaccone
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, U.K
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15
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Łapińska U, Saar KL, Yates EV, Herling TW, Müller T, Challa PK, Dobson CM, Knowles TPJ. Gradient-free determination of isoelectric points of proteins on chip. Phys Chem Chem Phys 2018; 19:23060-23067. [PMID: 28817152 DOI: 10.1039/c7cp01503h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isoelectric point (pI) of a protein is a key characteristic that influences its overall electrostatic behaviour. The majority of conventional methods for the determination of the isoelectric point of a molecule rely on the use of spatial gradients in pH, although significant practical challenges are associated with such techniques, notably the difficulty in generating a stable and well controlled pH gradient. Here, we introduce a gradient-free approach, exploiting a microfluidic platform which allows us to perform rapid pH change on chip and probe the electrophoretic mobility of species in a controlled field. In particular, in this approach, the pH of the electrolyte solution is modulated in time rather than in space, as in the case for conventional determinations of the isoelectric point. To demonstrate the general approachability of this platform, we have measured the isoelectric points of representative set of seven proteins, bovine serum albumin, β-lactoglobulin, ribonuclease A, ovalbumin, human transferrin, ubiquitin and myoglobin in microlitre sample volumes. The ability to conduct measurements in free solution thus provides the basis for the rapid determination of isoelectric points of proteins under a wide variety of solution conditions and in small volumes.
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Affiliation(s)
- Urszula Łapińska
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Kadi L Saar
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Emma V Yates
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Therese W Herling
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Thomas Müller
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. and Fluidic Analytics, Unit 5 Chesterton Mill, French's Road, Cambridge CB4 3NP, UK
| | - Pavan K Challa
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Christopher M Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
| | - Tuomas P J Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. and Department of Physics, Cavendish Laboratory, 19 J J Thomson Avenue, Cambridge CB3 0HE, UK
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Leandro SR, Mourato AC, Łapińska U, Monteiro OC, Fernandes CI, Vaz PD, Nunes CD. Exploring bulk and colloidal Mg/Al hydrotalcite–Au nanoparticles hybrid materials in aerobic olefin epoxidation. J Catal 2018. [DOI: 10.1016/j.jcat.2017.12.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Saar KL, Zhang Y, Müller T, Kumar CP, Devenish S, Lynn A, Łapińska U, Yang X, Linse S, Knowles TPJ. On-chip label-free protein analysis with downstream electrodes for direct removal of electrolysis products. Lab Chip 2017; 18:162-170. [PMID: 29192926 DOI: 10.1039/c7lc00797c] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The ability to apply highly controlled electric fields within microfluidic devices is valuable as a basis for preparative and analytical processes. A challenge encountered in the context of such approaches in conductive media, including aqueous buffers, is the generation of electrolysis products at the electrode/liquid interface which can lead to contamination, perturb fluid flows and generally interfere with the measurement process. Here, we address this challenge by designing a single layer microfluidic device architecture where the electric potential is applied outside and downstream of the microfluidic device while the field is propagated back to the chip via the use of a co-flowing highly conductive electrolyte solution that forms a stable interface at the separation region of the device. The co-flowing electrolyte ensures that all the generated electrolysis products, including Joule heat and gaseous products, are flowed away from the chip without coming into contact with the analytes while the single layer fabrication process where all the structures are defined lithographically allows producing the devices in a simple yet highly reproducible manner. We demonstrate that by allowing stable and effective application of electric fields in excess of 100 V cm-1, the described platform provides the basis for rapid separation of heterogeneous mixtures of proteins and protein complexes directly in their native buffers as well as for the simultaneous quantification of their charge states. We illustrate this by probing the interactions in a mixture of an amyloid forming protein, amyloid-β, and a molecular chaperone, Brichos, known to inhibit the process of amyloid formation. The availability of a platform for applying stable electric fields and its compatibility with single-layer soft-lithography processes opens up the possibility of separating and analysing a wide range of molecules on chip, including those with similar electrophoretic mobilities.
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Affiliation(s)
- Kadi L Saar
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
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