1
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Gault J, Liko I, Landreh M, Shutin D, Bolla JR, Jefferies D, Agasid M, Yen HY, Ladds MJGW, Lane DP, Khalid S, Mullen C, Remes PM, Huguet R, McAlister G, Goodwin M, Viner R, Syka JEP, Robinson CV. Combining native and 'omics' mass spectrometry to identify endogenous ligands bound to membrane proteins. Nat Methods 2020; 17:505-508. [PMID: 32371966 PMCID: PMC7332344 DOI: 10.1038/s41592-020-0821-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 03/25/2020] [Indexed: 02/08/2023]
Abstract
Ligands bound to protein assemblies provide critical information for function, yet are often difficult to capture and define. Here we develop a top-down method, 'nativeomics', unifying 'omics' (lipidomics, proteomics, metabolomics) analysis with native mass spectrometry to identify ligands bound to membrane protein assemblies. By maintaining the link between proteins and ligands, we define the lipidome/metabolome in contact with membrane porins and a mitochondrial translocator to discover potential regulators of protein function.
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Affiliation(s)
- Joseph Gault
- Department of Chemistry, University of Oxford, Oxford, UK.
| | - Idlir Liko
- Department of Chemistry, University of Oxford, Oxford, UK
- OMass Therapeutics, Oxford, UK
| | - Michael Landreh
- Department of Microbiology, Tumor and Cell Biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Denis Shutin
- Department of Chemistry, University of Oxford, Oxford, UK
| | | | | | - Mark Agasid
- Department of Chemistry, University of Oxford, Oxford, UK
| | | | - Marcus J G W Ladds
- Department of Microbiology, Tumor and Cell Biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - David P Lane
- Department of Microbiology, Tumor and Cell Biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, UK
| | | | | | | | | | | | - Rosa Viner
- Thermo Fisher Scientific, San Jose, CA, USA
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2
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Jefferies D, Khalid S. Atomistic and coarse-grained simulations of membrane proteins: A practical guide. Methods 2020; 185:15-27. [PMID: 32084518 DOI: 10.1016/j.ymeth.2020.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022] Open
Abstract
Membrane proteins are amphipathic macromolecules whose exposed hydrophobic surfaces promote interactions with lipid membranes. Membrane proteins are remarkably diverse in terms of chemical composition and correspondingly, their biological functions and general biophysical behavior. Conventional experimental techniques provide an approach to study specific properties of membrane proteins e.g. their surface features, the nature and abundance of stabilizing intramolecular forces, preferred bilayer orientation, and the characteristics of their annular lipid shells. Molecular modeling software-and in particular, the suite of molecular dynamics algorithms-enables a more comprehensive exploration of dynamic membrane protein behavior. Molecular dynamics methods enable users to produce stepwise trajectories of proteins on arbitrary spatiotemporal scales that enable the easy identification of dynamic interactions that are beyond the scope of conventional analytical techniques. This article explains the molecular dynamics theoretical framework and popular step-by-step approaches for simulating membrane proteins in planar, and to a lesser extent, nonplanar lipid geometries. We detail popular procedures and computational tools that produce well-packed configurations of lipids and proteins and additionally, the efficient molecular dynamics simulation algorithms that reproduce their dynamic interactions.
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Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
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3
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Jefferies D, Khalid S. To infect or not to infect: molecular determinants of bacterial outer membrane vesicle internalization by host membranes. J Mol Biol 2020; 432:1251-1264. [DOI: 10.1016/j.jmb.2020.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 12/13/2019] [Accepted: 01/06/2020] [Indexed: 02/08/2023]
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4
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Jefferies D, Shearer J, Khalid S. Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations. J Phys Chem B 2019; 123:3567-3575. [DOI: 10.1021/acs.jpcb.8b12168] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Jonathan Shearer
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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5
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Shearer J, Jefferies D, Khalid S. Outer Membrane Proteins OmpA, FhuA, OmpF, EstA, BtuB, and OmpX Have Unique Lipopolysaccharide Fingerprints. J Chem Theory Comput 2019; 15:2608-2619. [PMID: 30848905 DOI: 10.1021/acs.jctc.8b01059] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [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
The outer membrane of Gram-negative bacteria has a highly complex asymmetrical architecture, containing a mixture of phospholipids in the inner leaflet and almost exclusively lipopolysaccharide (LPS) molecules in the outer leaflet. In E. coli, the outer membrane contains a wide range of proteins with a β barrel architecture, that vary in size from the smallest having eight strands to larger barrels composed of 22 strands. Here we report coarse-grained molecular dynamics simulations of six proteins from the E. coli outer membrane OmpA, OmpX, BtuB, FhuA, OmpF, and EstA in a range of membrane environments, which are representative of the in vivo conditions for different strains of E. coli. We show that each protein has a unique pattern of interaction with the surrounding membrane, which is influenced by the composition of the protein, the level of LPS in the outer leaflet, and the differing mobilities of the lipids in the two leaflets of the membrane. Overall we present analyses from over 200 μs of simulation for each protein.
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Affiliation(s)
- Jonathan Shearer
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
| | - Damien Jefferies
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
| | - Syma Khalid
- School of Chemistry , University of Southampton, Highfield , Southampton , SO17 1BJ United Kingdom
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6
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Gupta A, Marzinek JK, Jefferies D, Bond PJ, Harryson P, Wohland T. The disordered plant dehydrin Lti30 protects the membrane during water-related stress by cross-linking lipids. J Biol Chem 2019; 294:6468-6482. [PMID: 30819802 DOI: 10.1074/jbc.ra118.007163] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [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: 12/14/2018] [Revised: 02/14/2019] [Indexed: 12/13/2022] Open
Abstract
Dehydrins are intrinsically disordered proteins, generally expressed in plants as a response to embryogenesis and water-related stress. Their suggested functions are in membrane stabilization and cell protection. All dehydrins contain at least one copy of the highly conserved K-segment, proposed to be a membrane-binding motif. The dehydrin Lti30 (Arabidopsis thaliana) is up-regulated during cold and drought stress conditions and comprises six K-segments, each with two adjacent histidines. Lti30 interacts with the membrane electrostatically via pH-dependent protonation of the histidines. In this work, we seek a molecular understanding of the membrane interaction mechanism of Lti30 by determining the diffusion and molecular organization of Lti30 on model membrane systems by imaging total internal reflection- fluorescence correlation spectroscopy (ITIR-FCS) and molecular dynamics (MD) simulations. The dependence of the diffusion coefficient explored by ITIR-FCS together with MD simulations yields insights into Lti30 binding, domain partitioning, and aggregation. The effect of Lti30 on membrane lipid diffusion was studied on fluorescently labeled supported lipid bilayers of different lipid compositions at mechanistically important pH conditions. In parallel, we compared the mode of diffusion for short individual K-segment peptides. The results indicate that Lti30 binds the lipid bilayer via electrostatics, which restricts the mobility of lipids and bound protein molecules. At low pH, Lti30 binding induced lipid microdomain formation as well as protein aggregation, which could be correlated with one another. Moreover, at physiological pH, Lti30 forms nanoscale aggregates when proximal to the membrane suggesting that Lti30 may protect the cell by "cross-linking" the membrane lipids.
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Affiliation(s)
- Anjali Gupta
- From the Center for BioImaging Sciences and.,the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore
| | - Jan K Marzinek
- the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore
| | - Damien Jefferies
- the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore.,the School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Peter J Bond
- the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore.,the Bioinformatics Institute (A*STAR), 30 Biopolis St., 07-01 Matrix, Singapore 138671, Singapore
| | - Pia Harryson
- the Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden, and
| | - Thorsten Wohland
- From the Center for BioImaging Sciences and .,the Department of Biological Sciences, National University of Singapore, 14 Science Dr. 4, Singapore 117543, Singapore.,Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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7
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Hsu PC, Bruininks BMH, Jefferies D, Cesar Telles de Souza P, Lee J, Patel DS, Marrink SJ, Qi Y, Khalid S, Im W. CHARMM-GUI Martini Maker for modeling and simulation of complex bacterial membranes with lipopolysaccharides. J Comput Chem 2017; 38:2354-2363. [PMID: 28776689 DOI: 10.1002/jcc.24895] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [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: 06/04/2017] [Revised: 07/03/2017] [Accepted: 07/09/2017] [Indexed: 12/18/2022]
Abstract
A complex cell envelope, composed of a mixture of lipid types including lipopolysaccharides, protects bacteria from the external environment. Clearly, the proteins embedded within the various components of the cell envelope have an intricate relationship with their local environment. Therefore, to obtain meaningful results, molecular simulations need to mimic as far as possible this chemically heterogeneous system. However, setting up such systems for computational studies is far from trivial, and consequently the vast majority of simulations of outer membrane proteins still rely on oversimplified phospholipid membrane models. This work presents an update of CHARMM-GUI Martini Maker for coarse-grained modeling and simulation of complex bacterial membranes with lipopolysaccharides. The qualities of the outer membrane systems generated by Martini Maker are validated by simulating them in bilayer, vesicle, nanodisc, and micelle environments (with and without outer membrane proteins) using the Martini force field. We expect this new feature in Martini Maker to be a useful tool for modeling large, complicated bacterial outer membrane systems in a user-friendly manner. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Pin-Chia Hsu
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Bart M H Bruininks
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, Groningen, AG, 9747, The Netherlands
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Paulo Cesar Telles de Souza
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, Groningen, AG, 9747, The Netherlands
| | - Jumin Lee
- Departments of Biological Sciences and Bioengineering, Lehigh University, Pennsylvania
| | - Dhilon S Patel
- Departments of Biological Sciences and Bioengineering, Lehigh University, Pennsylvania
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, Groningen, AG, 9747, The Netherlands
| | - Yifei Qi
- College of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, China
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Wonpil Im
- Departments of Biological Sciences and Bioengineering, Lehigh University, Pennsylvania
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8
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Jefferies D, Hsu PC, Khalid S. Through the Lipopolysaccharide Glass: A Potent Antimicrobial Peptide Induces Phase Changes in Membranes. Biochemistry 2017; 56:1672-1679. [DOI: 10.1021/acs.biochem.6b01063] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, U.K
| | - Pin-Chia Hsu
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, U.K
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, U.K
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9
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Hsu PC, Jefferies D, Khalid S. How do Peptides and Nanoparticles Interact with the Membranes of E. Coli? Insights from Molecular Dynamics. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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10
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Hsu PC, Jefferies D, Khalid S. Molecular Dynamics Simulations Predict the Pathways via Which Pristine Fullerenes Penetrate Bacterial Membranes. J Phys Chem B 2016; 120:11170-11179. [DOI: 10.1021/acs.jpcb.6b06615] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pin-Chia Hsu
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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11
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van den Berg B, Chembath A, Jefferies D, Basle A, Khalid S, Rutherford JC. Structural basis for Mep2 ammonium transceptor activation by phosphorylation. Nat Commun 2016; 7:11337. [PMID: 27088325 PMCID: PMC4852598 DOI: 10.1038/ncomms11337] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [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: 07/28/2015] [Accepted: 03/14/2016] [Indexed: 11/18/2022] Open
Abstract
Mep2 proteins are fungal transceptors that play an important role as ammonium sensors in fungal development. Mep2 activity is tightly regulated by phosphorylation, but how this is achieved at the molecular level is not clear. Here we report X-ray crystal structures of the Mep2 orthologues from Saccharomyces cerevisiae and Candida albicans and show that under nitrogen-sufficient conditions the transporters are not phosphorylated and present in closed, inactive conformations. Relative to the open bacterial ammonium transporters, non-phosphorylated Mep2 exhibits shifts in cytoplasmic loops and the C-terminal region (CTR) to occlude the cytoplasmic exit of the channel and to interact with His2 of the twin-His motif. The phosphorylation site in the CTR is solvent accessible and located in a negatively charged pocket ∼30 Å away from the channel exit. The crystal structure of phosphorylation-mimicking Mep2 variants from C. albicans show large conformational changes in a conserved and functionally important region of the CTR. The results allow us to propose a model for regulation of eukaryotic ammonium transport by phosphorylation.
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Affiliation(s)
- Bert van den Berg
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Anupama Chembath
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Damien Jefferies
- School of Chemistry, University of Southampton,
Highfield Campus, Southampton
SO17 1BJ, UK
| | - Arnaud Basle
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton,
Highfield Campus, Southampton
SO17 1BJ, UK
| | - Julian C. Rutherford
- Institute for Cell and Molecular Biosciences, The Medical
School, Newcastle University, Newcastle upon Tyne
NE2 4HH, UK
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12
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Clifton LA, Holt SA, Paracini N, Hughes AV, Khalid S, Jefferies D, Lakey JH. The Complex, Asymmetric, Escherichia Coli Envelope Studied by Neutron Scattering. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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13
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Hsu PC, Jefferies D, Hall BA, Khalid S. Carbon Nanoparticles and Their Differential Association with the Membranes of E. coli: A Coarse-Grained Molecular Dynamics Simulation Study. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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14
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Thakrar A, Jefferies D, Hunter L. Do trainees attending trauma calls have ATLS experience? Int J Surg 2015. [DOI: 10.1016/j.ijsu.2015.07.518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Clifton LA, Holt SA, Hughes AV, Daulton EL, Arunmanee W, Heinrich F, Khalid S, Jefferies D, Charlton TR, Webster JRP, Kinane CJ, Lakey JH. An Accurate In Vitro Model of the E. coli Envelope. ACTA ACUST UNITED AC 2015; 127:12120-12123. [PMID: 27346898 PMCID: PMC4871320 DOI: 10.1002/ange.201504287] [Citation(s) in RCA: 6] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/07/2015] [Indexed: 11/12/2022]
Abstract
Gram‐negative bacteria are an increasingly serious source of antibiotic‐resistant infections, partly owing to their characteristic protective envelope. This complex, 20 nm thick barrier includes a highly impermeable, asymmetric bilayer outer membrane (OM), which plays a pivotal role in resisting antibacterial chemotherapy. Nevertheless, the OM molecular structure and its dynamics are poorly understood because the structure is difficult to recreate or study in vitro. The successful formation and characterization of a fully asymmetric model envelope using Langmuir–Blodgett and Langmuir–Schaefer methods is now reported. Neutron reflectivity and isotopic labeling confirmed the expected structure and asymmetry and showed that experiments with antibacterial proteins reproduced published in vivo behavior. By closely recreating natural OM behavior, this model provides a much needed robust system for antibiotic development.
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Affiliation(s)
- Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Stephen A Holt
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)
| | - Arwel V Hughes
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Emma L Daulton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Wanatchaporn Arunmanee
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH (UK)
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, 5000 Forbes Ave. Pittsburgh, PA 15213 (USA); National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899 (USA)
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ (UK)
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ (UK)
| | - Timothy R Charlton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - John R P Webster
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Christian J Kinane
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH (UK)
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16
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Clifton LA, Holt SA, Hughes AV, Daulton EL, Arunmanee W, Heinrich F, Khalid S, Jefferies D, Charlton TR, Webster JRP, Kinane CJ, Lakey JH. An accurate in vitro model of the E. coli envelope. Angew Chem Int Ed Engl 2015; 54:11952-5. [PMID: 26331292 PMCID: PMC4600229 DOI: 10.1002/anie.201504287] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [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: 05/11/2015] [Revised: 08/07/2015] [Indexed: 11/05/2022]
Abstract
Gram-negative bacteria are an increasingly serious source of antibiotic-resistant infections, partly owing to their characteristic protective envelope. This complex, 20 nm thick barrier includes a highly impermeable, asymmetric bilayer outer membrane (OM), which plays a pivotal role in resisting antibacterial chemotherapy. Nevertheless, the OM molecular structure and its dynamics are poorly understood because the structure is difficult to recreate or study in vitro. The successful formation and characterization of a fully asymmetric model envelope using Langmuir-Blodgett and Langmuir-Schaefer methods is now reported. Neutron reflectivity and isotopic labeling confirmed the expected structure and asymmetry and showed that experiments with antibacterial proteins reproduced published in vivo behavior. By closely recreating natural OM behavior, this model provides a much needed robust system for antibiotic development.
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Affiliation(s)
- Luke A Clifton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Stephen A Holt
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)
| | - Arwel V Hughes
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Emma L Daulton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Wanatchaporn Arunmanee
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH (UK)
| | - Frank Heinrich
- Department of Physics, Carnegie Mellon University, 5000 Forbes Ave. Pittsburgh, PA 15213 (USA).,National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899 (USA)
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ (UK)
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ (UK)
| | - Timothy R Charlton
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - John R P Webster
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Christian J Kinane
- ISIS Pulsed Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford Campus, Didcot, Oxfordshire, OX11 OQX (UK)
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH (UK).
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17
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Berglund NA, Piggot TJ, Jefferies D, Sessions RB, Bond PJ, Khalid S. Interaction of the antimicrobial peptide polymyxin B1 with both membranes of E. coli: a molecular dynamics study. PLoS Comput Biol 2015; 11:e1004180. [PMID: 25885324 PMCID: PMC4401565 DOI: 10.1371/journal.pcbi.1004180] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/06/2015] [Indexed: 11/17/2022] Open
Abstract
Antimicrobial peptides are small, cationic proteins that can induce lysis of bacterial cells through interaction with their membranes. Different mechanisms for cell lysis have been proposed, but these models tend to neglect the role of the chemical composition of the membrane, which differs between bacterial species and can be heterogeneous even within a single cell. Moreover, the cell envelope of Gram-negative bacteria such as E. coli contains two membranes with differing compositions. To this end, we report the first molecular dynamics simulation study of the interaction of the antimicrobial peptide, polymyxin B1 with complex models of both the inner and outer membranes of E. coli. The results of >16 microseconds of simulation predict that polymyxin B1 is likely to interact with the membranes via distinct mechanisms. The lipopeptides aggregate in the lipopolysaccharide headgroup region of the outer membrane with limited tendency for insertion within the lipid A tails. In contrast, the lipopeptides readily insert into the inner membrane core, and the concomitant increased hydration may be responsible for bilayer destabilization and antimicrobial function. Given the urgent need to develop novel, potent antibiotics, the results presented here reveal key mechanistic details that may be exploited for future rational drug development.
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Affiliation(s)
- Nils A Berglund
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom; Bioinformatics Institute (A*STAR), Singapore
| | - Thomas J Piggot
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | | | - Peter J Bond
- Bioinformatics Institute (A*STAR), Singapore; Department of Biological Sciences, National University of Singapore, Singapore
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
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18
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Jefferies D, Johnson M, Nicholls D, Langdon R, Lad S. Evaluating an intensive ward-based writing coach programme to improve nursing documentation: lessons learned. Int Nurs Rev 2012; 59:394-401. [DOI: 10.1111/j.1466-7657.2012.00994.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- D Jefferies
- School of Nursing and Midwifery, Centre for Applied Nursing Research (Joint Facility of SSWAHS & the University of Western Sydney), College of Health & Science, University of Western Sydney, Sydney, NSW, Australia.
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19
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Thorp BH, Dick L, Jefferies D, Houston B, Wilson J. An assessment of the efficacy of the Lixiscope for the detection of tibial dyschondroplasia. Avian Pathol 2007; 26:97-104. [DOI: 10.1080/03079459708419197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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20
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White JML, White IR, Glendinning A, Fleming J, Jefferies D, Basketter DA, McFadden JP, Buckley DA. Frequency of allergic contact dermatitis to isoeugenol is increasing: a review of 3636 patients tested from 2001 to 2005. Br J Dermatol 2007; 157:580-2. [PMID: 17573874 DOI: 10.1111/j.1365-2133.2007.08017.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [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: 11/28/2022]
Abstract
BACKGROUND Isoeugenol is an important fragrance allergen. The cosmetic industry was recommended voluntarily to reduce concentrations of isoeugenol in finished cosmetic products from 0.2% to 0.02% in 1998. It was suspected that this would reduce the incidence of patch test positivity in individuals undergoing routine patch testing after approximately 2-3 years (the Dillarstone effect). OBJECTIVES To review our patch test data since the change in practice by industry, to see if there has been an observable decrease in isoeugenol contact sensitivity. METHODS We retrospectively analysed all subjects patch tested to isoeugenol 1% pet. in the St John's Department of Cutaneous Allergy over a period of 5 years, commencing 3 years after the changes. RESULTS We identified 3636 subjects, 97 of whom were positive for isoeugenol. Year-on-year incidence shows an increasing trend, with an overall incidence of 2.67%. Using the exact Cochran-Armitage test, this ascending trend is statistically significant (P = 0.0182). Seventy-two of 97 isoeugenol-positive subjects were also positive to fragrance mix I. Other fragrances positive in these 97 patients included Myroxylon pereirae (30%), Evernia prunastri (22%) and eugenol (15%). CONCLUSIONS We suspect that the increasing trend may be due to allergen substitution with compounds chemically related to isoeugenol, or which hydrolyse to isoeugenol itself.
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Affiliation(s)
- J M L White
- Department of Cutaneous Allergy, St John's Institute of Dermatology, St Thomas' Hospital, London SE1 7EH, UK.
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21
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22
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Ho SGY, Basketter DA, Jefferies D, Rycroft RJG, White IR, McFadden JP. Analysis of para-phenylenediamine allergic patients in relation to strength of patch test reaction. Br J Dermatol 2005; 153:364-7. [PMID: 16086750 DOI: 10.1111/j.1365-2133.2005.06742.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [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: 11/28/2022]
Abstract
BACKGROUND Despite having a positive patch test reaction to para-phenylenediamine (PPD), some patients continue to dye their hair, while others are forced to give up or abandon this practice. This difference in patient behaviour could be due to the degree of sensitization. OBJECTIVES To establish whether the ability to continue dyeing hair in PPD allergic patients is related to the strength of patch test reaction. To note differences in other clinical features in relation to the strength of patch test reaction. METHODS We analysed retrospectively the patch test records of 400 sequential PPD-positive patients for the strength of patch test reaction (+, ++, +++) and different clinical features. Data were analysed using Cochran-Mantel-Haenszel chi2 tests. RESULTS There was a strong linear relationship between the strength of patch test reaction and continuation with hair dyeing. Patients were more likely to report a history of hair dye reaction with increasing strength of patch test reaction. There was no difference in strength of patch test reaction in relation to age, site of rash, occupation (hairdressing) or history of atopic eczema. Overall concomitant reactivity with related aromatic amine allergens (benzocaine, N-isopropyl-N-phenyl-para-phenylenediamine, para-aminobenzoic acid) was infrequent. CONCLUSIONS Patients with stronger patch test reactions (++, +++) are more likely to have a clear history of reacting to hair dye and are less likely to still be dyeing their hair.
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Affiliation(s)
- S G Y Ho
- Contact Dermatitis Clinic, St John's Institute of Dermatology, St Thomas' Hospital, Lambeth Palace Rd, London SE1 7EH, UK
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23
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Wright C, Davenport EJ, Kan-King-Yu D, Jefferies D, Cubberley R, Lalljie SPD. Inter-laboratory comparison of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in bleaching earth used in the refinement of edible oils. Food Addit Contam 2005; 22:716-25. [PMID: 16147427 DOI: 10.1080/02652030500157643] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Bleaching earth (dried, powdered, bentonite-montmorillonite clay) is commonly used as a processing aid in edible oil refinement. Used bleaching earth may be incorporated into animal feed indirectly, for example because it is included into seed meal, or directly (e.g., as a binding agent). Control must be demonstrated to ensure that the levels of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in feed ingredients do not infringe European Community regulations. The low legislative action level assigned is analytically challenging and may be at or below the limits of quantification achievable by many laboratories. A statistical comparison (following the IUPAC/ISO/AOAC protocol) was made of analyses of PCDDs and PCDFs in selected bleaching earth samples by laboratories from Europe and the USA to assess the comparability of data. Of 19 sets of results submitted by laboratories for replicate samples, 11 demonstrated acceptable agreement.
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Affiliation(s)
- C Wright
- Safety and Environmental Assurance Centre, Unilever Colworth, Sharnbrook, UK.
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24
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Webster SV, Farquharson C, Jefferies D, Kwan APL. Expression of type X collagen, Indian hedgehog and parathyroid hormone related-protein in normal and tibial dyschondroplastic chick growth plates. Avian Pathol 2003; 32:69-80. [PMID: 12745383 DOI: 10.1080/030794502/000070741] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [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: 10/26/2022]
Abstract
Tibial dyschondroplasia (TD) is a form of aberrant endochondral ossification in chickens, in that a plug of avascular cartilage (TD lesion) is formed within the growth plate. Histologically, the lesion is filled with apparently transitional chondrocytes that have been unable to differentiate to hypertrophic chondrocytes. We have examined the spatial expression of mRNAs for type X collagen, Indian hedgehog (Ihh) and Parathyroid Hormone-related protein (PTHrP) in the TD growth plate by in situ hybridization in order to ascertain at which stage chondrocyte differentiation is arrested in TD. In the normal growth plate, type X collagen mRNA was expressed by both prehypertrophic and hypertrophic chondrocytes. Indian Hedgehog mRNA was detected in a band of prehypertrophic chondrocytes and PTHrP expression was localized to a narrow band of prehypertrophic chondrocytes and in osteoblasts within the diaphysis. In TD sections, collagen X expression was seen within differentiating cells, within a small number of lesion cells, and within hypertrophic chondrocytes on the diaphyseal side of the lesion. Ihh expression was also seen within the differentiating cells and throughout the lesion. These data indicate that chondrocyte differentiation is arrested at the transitional stage just prior to hypertrophy. Contrary to the previously reported PTHrP expression patterns in TD chicks by immunohistochemistry, PTHrP mRNA was not detected in the TD lesion. This observation probably reflects the cessation of PTHrP gene expression by chondrocytes in the more severe TD lesions. The results from the present study also imply that the arrest of cell differentiation in TD is independent of PTHrP and that endochondral ossification in the post-hatch avian growth plate may involve additional regulatory pathways.
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Affiliation(s)
- S V Webster
- Cardiff School of Biosciences, Cardiff University, P.O. Box 911, Cardiff CF1 3US, UK
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25
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Jefferies D, Farquharson C. Effects of choice of reverse-transcriptase enzyme and use of T4 gene 32 protein on banding patterns in agarose gel differential display. Anal Biochem 2002; 308:192-4. [PMID: 12234483 DOI: 10.1016/s0003-2697(02)00204-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- D Jefferies
- Bone Biology Group, Division of Integrative Biology, Roslin Institute, Midlothian, EH25 9PS, Scotland, UK.
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26
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Farquharson C, Jefferies D, Seawright E, Houston B. Regulation of chondrocyte terminal differentiation in the postembryonic growth plate: the role of the PTHrP-Indian hedgehog axis. Endocrinology 2001; 142:4131-40. [PMID: 11517192 DOI: 10.1210/endo.142.9.8396] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chondrocyte differentiation during embryonic bone growth is controlled by interactions between PTHrP and Indian hedgehog. We have now determined that the major components of this signaling pathway are present in the postembryonic growth plate. PTHrP was immunolocalized throughout the growth plate, and semiquantitative RT-PCR analysis of maturationally distinct chondrocyte fractions indicated that PTHrP, Indian hedgehog, and the PTH/PTHrP receptor were expressed at similar levels throughout the growth plate. However, patched, the hedgehog receptor, was more highly expressed in proliferating chondrocytes. Although all fractionated cells responded to PTHrP in culture by increasing thymidine incorporation and cAMP production and decreasing alkaline phosphatase activity, the magnitude of response was greatest in the proliferative chondrocytes. Bone morphogenetic proteins are considered likely intermediates in PTHrP signaling. Expression of bone morphogenetic protein-2 and 4--7 was detected within the growth plate, and PTHrP inhibited the expression of bone morphogenetic protein-4 and 6. Although organ culture studies indicated a possible paracrine role for epiphyseal chondrocyte-derived PTHrP in regulating growth plate chondrocyte differentiation, the presence within the postembryonic growth plate of functional components of the PTHrP-Indian hedgehog pathway suggests that local mechanisms intrinsic to the growth plate exist to control the rate of endochondral ossification.
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Affiliation(s)
- C Farquharson
- Bone Biology Group, Division of Integrative Biology, Roslin Institute, Roslin, Scotland, United Kingdom EH25 9PS.
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27
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Abstract
Growth plate cartilage is central to the process of bone elongation. Chondrocytes originating within the resting zone of the growth plate proceed through a series of intermediate phenotypes: proliferating, prehypertrophic and hypertrophic, before reaching a terminally differentiated state. Disruption of this chondrocyte maturational sequence causes many skeletal abnormalities in poultry such as tibial dyschondroplasia (TD), which is a common cause of deformity and lameness in the broiler chicken. Cell and matrix components of the growth plate have been studied in order to determine the cause(s) of the premature arrest of chondrocyte differentiation and retention of prehypertrophic chondrocytes observed in TD. Chondrocyte proliferation proceeds normally in TD, but markers of the differentiated phenotype, local growth factors, and the vitamin D receptor are abnormally expressed within the prehypertrophic chondrocytes above, and within, the lesion. Tibial dyschondroplasia is also associated with a reduced incidence of apoptosis, suggesting that the lesion contains an accumulation of immature cells that have outlived their normal life span. Immunolocalization studies of matrix components suggest an abnormal distribution within the TD growth plate that is consistent with a failure of the chondrocytes to fully hypertrophy. In addition, the collagen matrix of the TD lesion is highly crosslinked, which may make the formed lesion more impervious to vascular invasion and osteoclastic resorption. Recent studies have applied the techniques of differential display and semiquantitative reverse transcriptase-polymerase chain reaction to RNA obtained from discrete populations of growth plate chondrocytes of different maturational phenotypes. This strategy has allowed us to compare phenotypically identical cell fractions from normal and TD growth plates in an attempt to identify possible candidate genes for TD.
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Affiliation(s)
- C Farquharson
- Division of Integrative Biology, Roslin Institute, Scotland.
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28
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Jefferies D, Houston B, Lester D, Whitehead CC, Thorp BH, Botman M, Farquharson C. Expression patterns of chondrocyte genes cloned by differential display in tibial dyschondroplasia. Biochim Biophys Acta 2000; 1501:180-8. [PMID: 10838191 DOI: 10.1016/s0925-4439(00)00020-x] [Citation(s) in RCA: 19] [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: 11/30/2022]
Abstract
Tibial dyschondroplasia (TD) appears to involve a failure of the growth plate chondrocytes within growing long bones to differentiate fully to the hypertrophic stage, resulting in a mass of prehypertrophic chondrocytes which form the avascular TD lesion. Many biochemical and molecular markers of chondrocyte hypertrophy are absent from the lesion, or show reduced expression, but the cause of the disorder remains to be identified. As differentiation to the hypertrophic state is impaired in TD, we hypothesised that chondrocyte genes that are differentially expressed in the growth plate should show altered expression in TD. Using differential display, four genes, B-cadherin, EF2, HT7 and Ex-FABP were cloned from chondrocytes stimulated to differentiate to the hypertrophic stage in vitro, and their differential expression confirmed in vivo. Using semi-quantitative RT-PCR, the expression patterns of these genes were compared in chondrocytes from normal and TD growth plates. Surprisingly, none of these genes showed the pattern of expression that might be expected in TD lesion chondrocytes, and two of them, B-cadherin and Ex-FABP, were upregulated in the lesion. This indicates that the TD phenotype does not merely reflect the absence of hypertrophic marker genes, but may be influenced by more complex developmental mechanisms/defects than previously thought.
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Affiliation(s)
- D Jefferies
- Bone Biology Group, Division of Integrative Biology, Roslin Institute (Edinburgh), Roslin, EH25 9PS, Midlothian, UK.
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29
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Abstract
Terminal differentiation of growth-plate chondrocytes is accompanied by the acquisition of a spherical morphology and a large increase in cell volume. These changes are likely to be associated with rearrangement of the cytoskeleton, but little information on this aspect of chondrocyte hypertrophy is available. We report a role for microtubules in the control of chondrocyte maturation and hypertrophy. Chick growth-plate chondrocytes were fractionated into five maturationally distinct populations by Percoll density gradient centrifugation, and agarose gel differential display analysis was performed. We identified a 1200 bp cDNA fragment derived from a transcript that was most highly expressed in the hypertrophic chondrocytes. After cloning and sequencing, FASTA and BLAST analysis revealed 100% identity to chick beta7-tubulin. Differential expression was confirmed in a reverse transcription-polymerase chain reaction (RT-PCR) assay using specific primers for a 343 bp fragment from the 3' untranslated region of beta7-tubulin. Beta7-tubulin was upregulated three-fold in fully hypertrophic chondrocytes compared with the other four fractions, which all had similar levels of expression. Immunocytochemical localization of beta-tubulin in chick growth-plate sections demonstrated little staining in the chondrocytes of the proliferating zone, but intense cytoplasmic staining was present in the large hypertrophic chondrocytes. In cell culture studies, the addition of colchicine (10(-6) mol/L) resulted in a higher rate of [3H]-thymidine uptake (36.0%; p < 0.001), but lower amounts of alkaline phosphatase activity (69.1%; p < 0.001), collagen (49.1%; p < 0.01), and glycosaminoglycan (43.3%; p < 0.01) accumulation within the cell-matrix layer. Further evidence for the involvement of microtubules in chondrocyte differentiation and hypertrophy was obtained by morphological assessment of colchicine-treated growth-plate explant cultures. A partial failure of chondrocyte hypertrophy was observed, although collagen type X immunoreactivity was noted within the interstitial matrix. Further studies are required to identify the exact role of microtubules in chondrocyte hypertrophy, but the results presented here suggest that upregulation of beta-tubulin may be required for increased microtubule synthesis during changes in cell size during the hypertrophic process. In addition, as cell-matrix interactions are required for chondrocyte maturation, microtubules may promote the differentiated phenotype as a result of their role in Golgi-mediated secretion of matrix proteins.
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Affiliation(s)
- C Farquharson
- Bone Biology Group, Roslin Institute, Midlothian, Scotland, UK.
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30
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Lester DH, Farquharson C, Paton IR, Seawright E, Jefferies D, Whitehead CC, Burt DW, Houston B. A novel integral membrane protein is differentially expressed in the chick growth plate and maps to chromosome 1. Anim Genet 1999; 30:300-3. [PMID: 10467705 DOI: 10.1046/j.1365-2052.1999.00473.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [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
The growth plate is a specialised region of cartilage located at the growing ends of long bones in higher vertebrates. It is responsible for longitudinal bone growth and is under the control of many local and systemic factors. The growth plate consists of an orderly arrangement of small proliferative and larger mature hypertrophic chondrocytes. This paper describes the isolation by differential display of a 988-bp cDNA fragment derived from a transcript that is more highly expressed in proliferating rather than hypertrophic chondrocytes of the chick growth plate. Using 3' RACE, a further 939 bp of cDNA sequence was obtained. The 1.9 kb sequence contains a 924-bp open reading frame encoding an unknown 308 amino acid protein. This protein has a putative transmembrane domain near its N-terminus and three dileucine motifs at its carboxy tail. This gene was expressed in all other tissues examined. A polymorphism was identified by SSCP analysis and the gene was mapped to the centromeric region of the short arm of chicken chromosome 1, close to the locus for autosomal dwarfism.
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Affiliation(s)
- D H Lester
- Division of Integrative Biology, Roslin Institute, Edinburgh, Midlothian, Scotland
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31
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Rogers JL, Jefferies D. Putting the muscle into X-rays. RDH 1999; 19:34-6, 38, 40. [PMID: 10825896] [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] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- J L Rogers
- Department of Health Care Professions, College of Applied Sciences and Arts, Southern Illinois University, Carbondale, USA
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32
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Houston B, Seawright E, Jefferies D, Hoogland E, Lester D, Whitehead C, Farquharson C. Identification and cloning of a novel phosphatase expressed at high levels in differentiating growth plate chondrocytes. Biochim Biophys Acta 1999; 1448:500-6. [PMID: 9990301 DOI: 10.1016/s0167-4889(98)00153-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Growth plate chondrocytes progress through a proliferative phase before acquiring a terminally-differentiated phenotype. In this study we used Percoll density gradients to separate chick growth plate chondrocytes into populations of different maturational phenotype. By applying agarose gel differential display to these populations we cloned a cDNA encoding a novel 268 amino acid protein (3X11A). 3X11A contains two peptide motifs that are conserved in a recently identified superfamily of phosphotransferases. It is likely that 3X11A is a phosphatase, but its substrate specificity remains uncertain. 3X11A expression is upregulated 5-fold during chondrocyte terminal differentiation and its expression is approximately 100-fold higher in hypertrophic chondrocytes than in non-chondrogenic tissues. This suggests that 3X11A participates in a biochemical pathway that is particularly active in differentiating chondrocytes.
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Affiliation(s)
- B Houston
- Bone Biology Group, Roslin Institute, Midlothian, UK.
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Jefferies D, Botman M, Houston B, Whitehead CC, Thorp BH, Farquharson C. Expression patterns of candidate genes for tibial dyschondroplasia in chicken growth plate chondrocytes separated on percoll density gradients. Br Poult Sci 1998; 39 Suppl:S22-3. [PMID: 10188026 DOI: 10.1080/00071669888151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Affiliation(s)
- D Jefferies
- Roslin Institute, Edinburgh, Midlothian, Scotland
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Abstract
Phage display involves the production and screening of large numbers of random peptide sequences of a specific length expressed on the surface of phage particles. This approach provides a powerful tool to probe the molecular basis of many biological processes, including host-parasite interactions. Phage display libraries have been used to study the binding specificity of numerous peptides and protein domains. Practical applications include the identification of peptide sequences that bind with high affinity to antibodies, enzymes or receptors, and that may serve as diagnostics and vaccine or drug candidates. Here, David Jefferies outlines the concept of phage display and summarizes recent developments in the field, with emphasis on those that may be of interest to parasitologists.
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Jefferies D, Botman M, Farquharson C, Lester D, Whitehead CC, Thorp BH, Houston B. Cloning differentially regulated genes from chondrocytes using agarose gel differential display. Biochim Biophys Acta 1998; 1396:237-41. [PMID: 9545570 DOI: 10.1016/s0167-4781(97)00234-0] [Citation(s) in RCA: 12] [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: 02/07/2023]
Abstract
The technique of RNA differential display has been used extensively to clone differentially expressed genes from a wide variety of cells and tissues. Recently, a simplified method of cloning differential display products, separated on agarose gels, was described. Here we report an adaption of this method, using total RNA, to clone differentially expressed genes. The approach is simple and rapid, and requires only small quantities of total RNA. Utilising this approach, we have cloned three differentially regulated genes from chondrocytes stimulated to hypertrophy in vitro, and confirmed their pattern of expression by Northern blotting. These gene fragments were sequenced and found to correspond to known genes, although only one has previously been isolated from chondrocytes.
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Affiliation(s)
- D Jefferies
- Roslin Institute, Edinburgh, Midlothian, UK.
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36
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Graham SV, Jefferies D, Barry JD. A promotor directing alpha-amanitin-sensitive transcription of GARP, the major surface antigen of insect stage Trypanosoma congolense. Nucleic Acids Res 1996; 24:272-81. [PMID: 8628650 PMCID: PMC145629 DOI: 10.1093/nar/24.2.272] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [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: 02/01/2023] Open
Abstract
The major surface antigen of procyclic and epimastigote forms of Trypanosoma congolense in the tsetse fly is GARP (glutamic acid/alanine-rich protein), which is thought to be the analogue of procyclin/PARP in Trypanosoma brucei. We have studied two T.congolense GARP loci (the 4.3 and 4.4 loci) whose transcription is alpha-amanitin sensitive. Whilst a transcriptional gap 5' of the first GARP gene in the cloned region of the 4.4 locus could not be detected, such a gap was present in the 5' flank of the first GARP gene in the 4.3 locus. We have located a GARP transcription start site and, using reporter gene constructs containing a putative GARP promoter region in transient transfection studies, we have demonstrated promoter activity for the test region in T.congolense. There are species-specific differences in sequences regulating expression of the two major surface antigens, GARP and procyclin/PARP: the GARP promoter is inactive in T.brucei while the procyclin/PARP promoter is inactive in T.congolense. We have defined the splice acceptor site for the 4.3 GARP gene by sequencing and by 5' RT-PCR and demonstrated microheterogeneity in GARP polyadenylation by 3' RT-PCR. It appears that some GARP and procyclin/PARP RNA processing signals, although similar, are also species-specific.
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Affiliation(s)
- S V Graham
- Wellcome Unit of Molecular Parasitology, The Anderson College, University of Glasgow, UK
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37
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Berberof M, Vanhamme L, Tebabi P, Pays A, Jefferies D, Welburn S, Pays E. The 3′-terminal region of the mRNAs for VSG and procyclin can confer stage specificity to gene expression in Trypanosoma brucei. EMBO J 1995; 14:2925-34. [PMID: 7796818 PMCID: PMC398412 DOI: 10.1002/j.1460-2075.1995.tb07292.x] [Citation(s) in RCA: 82] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The variant surface glycoprotein (VSG) and procyclin are the respective major surface antigens of the bloodstream and the procyclic forms of Trypanosoma brucei. These proteins and their mRNAs are both the most abundant and absolutely characteristic of their respective life cycle stages. We show that the 3'-terminal region of these mRNAs regulates expression of a reporter gene in an inverse manner, depending on the developmental form of the parasite. In the case of VSG mRNA, the 97 nt sequence upstream from the polyadenylation site is responsible for these effects. The regulation occurs through a variation of mRNA abundance which is not due to a change in primary transcription. In the bloodstream form this effect is manifested by an increase in RNA stability, whereas in the procyclic form it seems to be related to a reduction in the efficiency of mRNA maturation. The 3'-end of VSG mRNA can obviate the 5- to 10-fold stimulation of transcription driven by the procyclin promoter during differentiation from the bloodstream to the procyclic form. The predominance of posttranscriptional over transcriptional controls is probably linked to the organization of the trypanosome genome in polycistronic transcription units.
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MESH Headings
- Animals
- Base Sequence
- Gene Expression Regulation, Developmental/genetics
- Genes, Reporter/genetics
- Membrane Glycoproteins/genetics
- Molecular Sequence Data
- Promoter Regions, Genetic/genetics
- Protozoan Proteins
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- Regulatory Sequences, Nucleic Acid/genetics
- Transcription, Genetic
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/growth & development
- Variant Surface Glycoproteins, Trypanosoma/genetics
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Affiliation(s)
- M Berberof
- Department of Molecular Biology, Free University of Brussels, Rhode St Genèse, Belgium
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Jefferies D, Tebabi P, Le Ray D, Pays E. The ble resistance gene as a new selectable marker for Trypanosoma brucei: fly transmission of stable procyclic transformants to produce antibiotic resistant bloodstream forms. Nucleic Acids Res 1993; 21:191-5. [PMID: 8441627 PMCID: PMC309091 DOI: 10.1093/nar/21.2.191] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [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: 01/30/2023] Open
Abstract
We describe here the stable transformation of Trypanosoma brucei using a new selectable marker for kinetoplastid protozoa, the Sh ble, or phleomycin, resistance gene. A plasmid containing this gene targeted to the tubulin gene locus by homologous sequences was introduced into procyclic trypanosomes by electroporation and cells selected for antibiotic resistance. Southern analysis of stable transformants showed that the plasmid had been integrated into the tubulin locus by homologous recombination. Analysis of bloodstream stage transformants, produced by transmission through the vector Glossina, showed that the resistance gene was conserved and expressed in these forms in the absence of selective drug pressure. In both procyclic and bloodstream forms, transcription of the ble gene appears to originate from the upstream tubulin promoter, despite the presence of a VSG promoter in the integrated construct. The generation of stable bloodstream transformants for the first time will facilitate the study of gene function and expression during the trypanosome life cycle, and aid in the investigation of genetic exchange in these organisms.
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Affiliation(s)
- D Jefferies
- Department of Molecular Biology, University of Brussels, Rhode-St-Genese, Belgium
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Abstract
The actin genes of Trypanosoma brucei are transcribed constitutively during the parasite life-cycle, by a polymerase sensitive to alpha-amanitin. The start region of the actin gene transcription unit was mapped by virtue of the accumulation of promoter-proximal transcripts which occurs following moderate UV irradiation. This region, located about 4 kilobases upstream from the genes, was able to direct transient expression of the bacterial Chloramphenicol Acetyl Transferase (CAT) gene in both bloodstream and procyclic forms of the parasite. The essential region of the promoter was defined by deletion, and appeared to be within 600 bp upstream from the putative transcription start site. It does not share significant homology with the other trypanosome promoters described so far (VSG, procyclin, rDNA), which all direct alpha-amanitin resistant transcription.
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Affiliation(s)
- M F Ben Amar
- Department of Molecular Biology, University of Brussels, Belgium
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Jefferies D, Morris JW, White VP. KVP meter errors induced by plastic wrap. J Dent Hyg 1991; 65:91-3. [PMID: 1856747] [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] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The purpose of this study was to determine whether erroneous kVp meter readings, induced by plastic wrap, affected the actual kVp (output) of a dental X-ray machine. To evaluate the effect of plastic wrap on dental X-ray machine kVp meters, a radiation output device was used to measure output in mR/ma.s. An intraoral dental X-ray unit (S.S. White Model #90W) was used to make the exposures. First, the kVp meter was not covered with plastic wrap and output readings were recorded at various kVp settings with the milliamperage and time held constant. Secondly, the same kVp settings were selected before the plastic wrap was placed. Milliamperage and time were again held to the same constant. The X-ray console was then covered with plastic wrap prior to measuring the output for each kVp. The wrap possessed a static charge. This charge induced erroneous kVp meter readings. Out-put readings at the various induced kVp settings were then recorded. A kVp of 50 with no wrap present resulted in the same output as a kVp of 50 induced to read 40 or 60 kVp by the presence of wrap. Similar results were obtained at other kVp settings. This indicates that the plastic wrap influences only the kVp meter needle and not the actual kilovoltage of the X-ray machine. Dental X-ray machine operators should select kVp meter readings prior to placing plastic wrap and should not adjust initial settings if the meter is deflected later by the presence of wrap. The use of such a procedure will result in proper exposures, fewer retakes, and less patient radiation. If plastic wrap leads to consistent exposure errors, clinicians may wish to use a 0.5% sodium hypochlorite disinfectant as an alternative to the barrier technique.
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Affiliation(s)
- D Jefferies
- College of Technical Careers, Southern Illinois University, Carbondale
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Pays E, Coquelet H, Tebabi P, Pays A, Jefferies D, Steinert M, Koenig E, Williams RO, Roditi I. Trypanosoma brucei: constitutive activity of the VSG and procyclin gene promoters. EMBO J 1990; 9:3145-51. [PMID: 1698609 PMCID: PMC552043 DOI: 10.1002/j.1460-2075.1990.tb07512.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.4] [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: 11/10/2022] Open
Abstract
The variant surface glycoprotein (VSG) and procyclin are the major surface proteins of the bloodstream and procyclic stages, respectively, of Trypanosoma brucei. The promoter regions of the VSG and procyclin gene transcription units could be mapped thanks to the specific enrichment of initial transcripts that occurs following UV irradiation. Whereas the VSG gene is 45 kb distant from its promoter, procyclin genes are located immediately downstream. We show, by run-on assays on isolated nuclei and by cDNA analysis, that transcription occurs from both promoters in bloodstream as well as in procyclic forms. It is inferred that the control of the stage-specific expression of VSG and procyclin genes is not effected at the level of transcription initiation, but most probably by interfering with the elongation and stability of the specific transcripts.
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Affiliation(s)
- E Pays
- Department of Molecular Biology, University of Brussels, Belgium
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Abstract
Thirty two patients with beta thalassaemia and sickle cell disease who were having regular blood transfusions were selected to test the efficacy and immunogenicity of low dose (2 micrograms or 0.1 ml) intradermal hepatitis B vaccine compared with the standard (20 micrograms or 1 ml) intramuscular dose. There was no significant difference in the rates of seroconversion, seroconversion had occurred in all patients by seven months. There were no significant differences in antibody titres between the intramuscular and intradermal groups at 1, 2, and 6 months. Although the titres were significantly higher in the intramuscular group at seven months and at 12-18 months, the antibody titre in the intradermal group did not fall below 10 IU/l. The results of this study suggest that low dose intradermal hepatitis B vaccination is an effective and economical way of stimulating an immune response in patients with beta thalassaemia and sickle cell disease.
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Affiliation(s)
- Q Mok
- Whittington Hospital, London
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Jefferies D, Jenni L. The effect of the trypanocidal drugs berenil and samorin on infections of Glossina morsitans centralis by Trypanosoma congolense. Acta Trop 1987; 44:369-70. [PMID: 2892374] [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: 01/03/2023]
Affiliation(s)
- D Jefferies
- Swiss Tropical Institute, Basel, Switzerland
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Jefferies D, Jenni L. The effect of trypanocidal drugs on the transmission of Trypanosoma brucei brucei by Glossina morsitans centralis. Acta Trop 1987; 44:23-8. [PMID: 2884836] [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: 01/03/2023]
Abstract
The effects of trypanocidal drugs on Trypanosoma b. brucei infections in Glossina m. centralis have been investigated. Pentamidine and suramin exhibited no significant effects but both berenil and samorin reduced the number of salivary gland infections in comparison with controls. Berenil at concentrations of 10, 1.0 and 0.1 microgram/ml significantly reduced the number of mature infections when fed to flies throughout the whole period of trypanosome development. A similar result was obtained with samorin at 0.1 microgram/ml. Subsequent experiments showed that administration of both drugs at an early stage was more effective in preventing the maturation of infection than a later but more prolonged administration. Reported drug levels in the blood of different experimental host animals are of the same magnitude as those used here. It is suggested that repeated feeding of T. b. brucei infected Glossina on drug-treated hosts may reduce transmission, although alternative bloodmeal sources would reduce this effect. These influences are worthy of investigation in the field.
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Abstract
Five types of sensilla were identified at the entrance to or within the food canal in female Simulium damnosum s.l., four on the labrum and one in the cibarium. The external morphology of these sense organs was investigated using scanning electron microscopy. Other cuticular projections present do not appear to be sensory in nature. No differences were found in the number, position, or fine structure of the mouthpart sensilla in two different cytospecies of S. damnosum, S. sanctipauli Vajime &Dunbar and S. sirbanum Vajime &Dunbar.
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Abstract
Five types of sensilla have been identified on the distal tip of the fascicle and within the food canal in the female of Lutzomyia longipalpis Lutz &Neiva, four on the labrum and one in the cibarium. The external morphology of these sensilla is described for the first time, using scanning electron microscopy, allowing a more direct comparison with the mouthpart sense organs present in other groups of haematophagous Diptera. No evidence for the presence of cibarial chemoreceptors was found although such sensilla have been reported in all other groups of Diptera examined.
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Abstract
In a percentage of laboratory bred Glossina infected with Trypanosoma congolense or T. vivax, trypanosomes colonized the cibarium as well as the midgut and/or the proboscis. Field-caught tsetse flies also had T. congolense and T. vivax cibarial infections. T. congolense cibarial infections occurred in all species of Glossina examined: G. tachinoides, G. palpalis palpalis, G. morsitans morsitans and G. m. submorsitans. T. vivax was only found in the cibarium of G. tachinoides. Trypanosomes were firmly attached in the cibarium, as shown by scanning electron microscopy. Two field-caught G. tachinoides were also discovered to have only cibarial infections, presumably of T. vivax. More information is required on the occurrence of cibarial infections in Glossina, especially in the field. It is suggested that examination of the cibarium should be carried out as part of the routine dissection of tsetse flies in the field.
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Abstract
Evidence from many sources indicates that, in several parasite–vector systems, flight ability, fecundity or gonotrophic concordance of vectors, are affected by parasites (including bacteria, rickettsia and viruses) and in some cases parasites cause well-documented pathogenic effects (see reviews, for example, by Lavoipierre (1958a) and Hawking & Worms (1961) on filaria; Molyneux (1977, 1983) for trypanosomatids; Killick-Kendrick (1979) for Leishmania).
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Jefferies D, Livesey JL, Molyneux DH. Fluid mechanics of bloodmeal uptake by Leishmania-infected sandflies. Acta Trop 1986; 43:43-53. [PMID: 2872786] [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: 01/03/2023]
Abstract
The fluid mechanics of blood flow in the pharynx and cibarium of Phlebotomus papatasi are described using a simple static model. The flow is characterized as viscous laminar. The Hagen-Poiseuille equation is used to assess the effects of attached parasites in the foregut of Leishmania-infected sandflies on blood flow. The reductions in flow rate imposed by parasite colonization of the pharynx and cibarium will reduce the ability of an infected fly to take a bloodmeal, thus encouraging further probing, enhancing transmission. Regurgitation of the contents of the foregut is also possible. This will aid the deposition of infective forms from the foregut. Transmission by means of regurgitation of parasites from the midgut is considered unlikely.
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