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Li M, Jørgensen SK, McMillan DGG, Krzemiński Ł, Daskalakis NN, Partanen RH, Tutkus M, Tuma R, Stamou D, Hatzakis NS, Jeuken LJC. Single Enzyme Experiments Reveal a Long-Lifetime Proton Leak State in a Heme-Copper Oxidase. J Am Chem Soc 2015; 137:16055-63. [PMID: 26618221 PMCID: PMC4697922 DOI: 10.1021/jacs.5b08798] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Heme-copper oxidases (HCOs) are key
enzymes in prokaryotes and
eukaryotes for energy production during aerobic respiration. They
catalyze the reduction of the terminal electron acceptor, oxygen,
and utilize the Gibbs free energy to transport protons across a membrane
to generate a proton (ΔpH) and electrochemical gradient termed
proton motive force (PMF), which provides the driving force for the
adenosine triphosphate (ATP) synthesis. Excessive PMF is known to
limit the turnover of HCOs, but the molecular mechanism of this regulatory
feedback remains relatively unexplored. Here we present a single-enzyme
study that reveals that cytochrome bo3 from Escherichia coli, an HCO closely homologous
to Complex IV in human mitochondria, can enter a rare, long-lifetime
leak state during which proton flow is reversed. The probability of
entering the leak state is increased at higher ΔpH. By rapidly
dissipating the PMF, we propose that this leak state may enable cytochrome bo3, and possibly other HCOs, to maintain a suitable
ΔpH under extreme redox conditions.
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Affiliation(s)
- Mengqiu Li
- School of Biomedical Sciences, University of Leeds , LS2 9JT Leeds, U.K
| | - Sune K Jørgensen
- Department of Chemistry, Nano-Science Center and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen , 2100 Copenhagen, Denmark
| | | | - Łukasz Krzemiński
- School of Biomedical Sciences, University of Leeds , LS2 9JT Leeds, U.K
| | | | - Riitta H Partanen
- School of Biomedical Sciences, University of Leeds , LS2 9JT Leeds, U.K
| | - Marijonas Tutkus
- Department of Chemistry, Nano-Science Center and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Roman Tuma
- School of Molecular and Cellular Biology, University of Leeds , LS2 9JT Leeds, U.K
| | - Dimitrios Stamou
- Department of Chemistry, Nano-Science Center and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Nikos S Hatzakis
- Department of Chemistry, Nano-Science Center and Lundbeck Foundation Center for Biomembranes in Nanomedicine, University of Copenhagen , 2100 Copenhagen, Denmark
| | - Lars J C Jeuken
- School of Biomedical Sciences, University of Leeds , LS2 9JT Leeds, U.K
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Site-specific presentation of single recombinant proteins in defined nanoarrays. Biointerphases 2010; 2:44-8. [PMID: 20408635 DOI: 10.1116/1.2713991] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The authors describe the deposition of single biomolecules on substrates at defined spacing by pure self-assembly. The substrate is equipped with an array of 8 nm large gold particles which form the template for biomolecule binding. The authors verified the successful binding of single biomolecules via specific antibody labeling and imaging by fluorescence microscopy. Scanning force microscopy provided evidence that every gold nanoparticle of the pattern is occupied by at least one biomolecule. Furthermore, gold conjugated secondary antibodies in combination with scanning electron microscopy proved that at least 75% of the nanoparticles carried only one active biomolecule. The precision given by such surface densities is molecularly defined and such considerably higher than in any other case reported so far.
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Addressable adsorption of lipid vesicles and subsequent protein interaction studies. Biointerphases 2008; 3:29. [DOI: 10.1116/1.2921867] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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