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Jarman OD, Hirst J. Membrane-domain mutations in respiratory complex I impede catalysis but do not uncouple proton pumping from ubiquinone reduction. PNAS NEXUS 2022; 1:pgac276. [PMID: 36712358 PMCID: PMC9802314 DOI: 10.1093/pnasnexus/pgac276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 12/01/2022] [Indexed: 12/05/2022]
Abstract
Respiratory complex I [NADH:ubiquinone (UQ) oxidoreductase] captures the free energy released from NADH oxidation and UQ reduction to pump four protons across an energy-transducing membrane and power ATP synthesis. Mechanisms for long-range energy coupling in complex I have been proposed from structural data but not yet evaluated by robust biophysical and biochemical analyses. Here, we use the powerful bacterial model system Paracoccus denitrificans to investigate 14 mutations of key residues in the membrane-domain Nqo13/ND4 subunit, defining the rates and reversibility of catalysis and the number of protons pumped per NADH oxidized. We reveal new insights into the roles of highly conserved charged residues in lateral energy transduction, confirm the purely structural role of the Nqo12/ND5 transverse helix, and evaluate a proposed hydrated channel for proton uptake. Importantly, even when catalysis is compromised the enzyme remains strictly coupled (four protons are pumped per NADH oxidized), providing no evidence for escape cycles that circumvent blocked proton-pumping steps.
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Affiliation(s)
- Owen D Jarman
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
| | - Judy Hirst
- The Medical Research Council Mitochondrial Biology Unit, University of Cambridge, The Keith Peters Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, UK
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2
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Li C, Hu Q, Liang Y, Wei Y, Wang J. Physicochemical properties and application in film preparation of prolamin from distiller's grains. Int J Food Sci Technol 2022. [DOI: 10.1111/ijfs.15831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chen Li
- School of Life Science Shanxi University Taiyuan 030006 Shanxi China
- Xinghuacun College of Shanxi University Taiyuan 030006 Shanxi China
| | - Qiannan Hu
- School of Life Science Shanxi University Taiyuan 030006 Shanxi China
| | - Yaqi Liang
- School of Life Science Shanxi University Taiyuan 030006 Shanxi China
| | - Yuxiang Wei
- School of Life Science Shanxi University Taiyuan 030006 Shanxi China
| | - Jingxue Wang
- School of Life Science Shanxi University Taiyuan 030006 Shanxi China
- Xinghuacun College of Shanxi University Taiyuan 030006 Shanxi China
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3
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Barthels F, Hammerschmidt SJ, Fischer TR, Zimmer C, Kallert E, Helm M, Kersten C, Schirmeister T. A low-cost 3D-printable differential scanning fluorometer for protein and RNA melting experiments. HARDWAREX 2022; 11:e00256. [PMID: 35509940 PMCID: PMC9058602 DOI: 10.1016/j.ohx.2022.e00256] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/02/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
Differential scanning fluorimetry (DSF) is a widely used biophysical technique with applications to drug discovery and protein biochemistry. DSF experiments are commonly performed in commercial real-time polymerase chain reaction (qPCR) thermal cyclers or nanoDSF instruments. Here, we report the construction, validation, and example applications of an open-source DSF system for 176 €, which, in addition to protein-DSF experiments, also proved to be a versatile biophysical instrument for less conventional RNA-DSF experiments. Using 3D-printed parts made of polyoxymethylene, we were able to fabricate a thermostable machine chassis for protein-melting experiments. The combination of blue high-power LEDs as the light source and stage light foil as filter components was proven to be a reliable and affordable alternative to conventional optics equipment for the detection of SYPRO Orange or Sybr Gold fluorescence. The ESP32 microcontroller is the core piece of this openDSF instrument, while the in-built I2S interface was found to be a powerful analog-to-digital converter for fast acquisition of fluorescence and temperature data. Airflow heating and inline temperature control by thermistors enabled high-accuracy temperature management in PCR tubes (±0.1 °C) allowing us to perform high-resolution thermal shift assays (TSA) from exemplary biological applications.
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4
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Van den Bergh B, Schramke H, Michiels JE, Kimkes TEP, Radzikowski JL, Schimpf J, Vedelaar SR, Burschel S, Dewachter L, Lončar N, Schmidt A, Meijer T, Fauvart M, Friedrich T, Michiels J, Heinemann M. Mutations in respiratory complex I promote antibiotic persistence through alterations in intracellular acidity and protein synthesis. Nat Commun 2022; 13:546. [PMID: 35087069 PMCID: PMC8795404 DOI: 10.1038/s41467-022-28141-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 01/04/2022] [Indexed: 11/28/2022] Open
Abstract
Antibiotic persistence describes the presence of phenotypic variants within an isogenic bacterial population that are transiently tolerant to antibiotic treatment. Perturbations of metabolic homeostasis can promote antibiotic persistence, but the precise mechanisms are not well understood. Here, we use laboratory evolution, population-wide sequencing and biochemical characterizations to identify mutations in respiratory complex I and discover how they promote persistence in Escherichia coli. We show that persistence-inducing perturbations of metabolic homeostasis are associated with cytoplasmic acidification. Such cytoplasmic acidification is further strengthened by compromised proton pumping in the complex I mutants. While RpoS regulon activation induces persistence in the wild type, the aggravated cytoplasmic acidification in the complex I mutants leads to increased persistence via global shutdown of protein synthesis. Thus, we propose that cytoplasmic acidification, amplified by a compromised complex I, can act as a signaling hub for perturbed metabolic homeostasis in antibiotic persisters.
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Affiliation(s)
- Bram Van den Bergh
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
- Center for Microbiology, Flanders Institute for Biotechnology, VIB, Leuven, Belgium
- Department of Entomology, Cornell University, Ithaca, NY, USA
| | - Hannah Schramke
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Joran Elie Michiels
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
- Center for Microbiology, Flanders Institute for Biotechnology, VIB, Leuven, Belgium
| | - Tom E P Kimkes
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Jakub Leszek Radzikowski
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Johannes Schimpf
- Molecular Bioenergetics, Institute of Biochemistry, Albert-Ludwigs-University of Freiburg, Freiburg im Breisgau, Germany
| | - Silke R Vedelaar
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Sabrina Burschel
- Molecular Bioenergetics, Institute of Biochemistry, Albert-Ludwigs-University of Freiburg, Freiburg im Breisgau, Germany
| | - Liselot Dewachter
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
- Center for Microbiology, Flanders Institute for Biotechnology, VIB, Leuven, Belgium
| | - Nikola Lončar
- Molecular Enzymology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Alexander Schmidt
- Proteomics Core Facility, Biozentrum, University of Basel, Basel, Switzerland
| | - Tim Meijer
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands
| | - Maarten Fauvart
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium
- Center for Microbiology, Flanders Institute for Biotechnology, VIB, Leuven, Belgium
- imec, Leuven, Belgium
| | - Thorsten Friedrich
- Molecular Bioenergetics, Institute of Biochemistry, Albert-Ludwigs-University of Freiburg, Freiburg im Breisgau, Germany
| | - Jan Michiels
- Centre of Microbial and Plant Genetics, Department of Molecular and Microbial Systems, KU Leuven, Leuven, Belgium.
- Center for Microbiology, Flanders Institute for Biotechnology, VIB, Leuven, Belgium.
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen, The Netherlands.
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5
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Schulte M, Frick K, Gnandt E, Jurkovic S, Burschel S, Labatzke R, Aierstock K, Fiegen D, Wohlwend D, Gerhardt S, Einsle O, Friedrich T. A mechanism to prevent production of reactive oxygen species by Escherichia coli respiratory complex I. Nat Commun 2019; 10:2551. [PMID: 31186428 PMCID: PMC6560083 DOI: 10.1038/s41467-019-10429-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 05/08/2019] [Indexed: 11/21/2022] Open
Abstract
Respiratory complex I plays a central role in cellular energy metabolism coupling NADH oxidation to proton translocation. In humans its dysfunction is associated with degenerative diseases. Here we report the structure of the electron input part of Aquifex aeolicus complex I at up to 1.8 Å resolution with bound substrates in the reduced and oxidized states. The redox states differ by the flip of a peptide bond close to the NADH binding site. The orientation of this peptide bond is determined by the reduction state of the nearby [Fe-S] cluster N1a. Fixation of the peptide bond by site-directed mutagenesis led to an inactivation of electron transfer and a decreased reactive oxygen species (ROS) production. We suggest the redox-gated peptide flip to represent a previously unrecognized molecular switch synchronizing NADH oxidation in response to the redox state of the complex as part of an intramolecular feed-back mechanism to prevent ROS production. Respiratory complex I plays a central role in cellular energy metabolism coupling NADH oxidation to proton translocation. Here, the authors report the structure of the electron input part of Aquifex aeolicus complex I at up to 1.8 Å resolution with bound substrates in the reduced and oxidized states.
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Affiliation(s)
- Marius Schulte
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Klaudia Frick
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Emmanuel Gnandt
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Sascha Jurkovic
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Sabrina Burschel
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Ramona Labatzke
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Karoline Aierstock
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany.,Boehringer Ingelheim Pharma GmbH & Co. KG, Lead Identification and Optimization Sup, 88397, Biberach, Germany
| | - Dennis Fiegen
- Boehringer Ingelheim Pharma GmbH & Co. KG, Lead Identification and Optimization Sup, 88397, Biberach, Germany
| | - Daniel Wohlwend
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Stefan Gerhardt
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Oliver Einsle
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, Schänzlestrasse 1, 79104, Freiburg, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany.
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6
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Bai N, Roder H, Dickson A, Karanicolas J. Isothermal Analysis of ThermoFluor Data can readily provide Quantitative Binding Affinities. Sci Rep 2019; 9:2650. [PMID: 30804351 PMCID: PMC6389909 DOI: 10.1038/s41598-018-37072-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/30/2018] [Indexed: 01/20/2023] Open
Abstract
Differential scanning fluorimetry (DSF), also known as ThermoFluor or Thermal Shift Assay, has become a commonly-used approach for detecting protein-ligand interactions, particularly in the context of fragment screening. Upon binding to a folded protein, most ligands stabilize the protein; thus, observing an increase in the temperature at which the protein unfolds as a function of ligand concentration can serve as evidence of a direct interaction. While experimental protocols for this assay are well-developed, it is not straightforward to extract binding constants from the resulting data. Because of this, DSF is often used to probe for an interaction, but not to quantify the corresponding binding constant (Kd). Here, we propose a new approach for analyzing DSF data. Using unfolding curves at varying ligand concentrations, our "isothermal" approach collects from these the fraction of protein that is folded at a single temperature (chosen to be temperature near the unfolding transition). This greatly simplifies the subsequent analysis, because it circumvents the complicating temperature dependence of the binding constant; the resulting constant-temperature system can then be described as a pair of coupled equilibria (protein folding/unfolding and ligand binding/unbinding). The temperature at which the binding constants are determined can also be tuned, by adding chemical denaturants that shift the protein unfolding temperature. We demonstrate the application of this isothermal analysis using experimental data for maltose binding protein binding to maltose, and for two carbonic anhydrase isoforms binding to each of four inhibitors. To facilitate adoption of this new approach, we provide a free and easy-to-use Python program that analyzes thermal unfolding data and implements the isothermal approach described herein ( https://sourceforge.net/projects/dsf-fitting ).
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Affiliation(s)
- Nan Bai
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, 66045, USA
| | - Heinrich Roder
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Alex Dickson
- Department of Biochemistry & Molecular Biology and Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - John Karanicolas
- Program in Molecular Therapeutics, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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