Imperial College London
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DrMaxieRoessler

Faculty of Natural Sciences, Department of Chemistry

Reader in EPR Spectroscopy
 
 
 
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Contact

 

+44 (0)20 7594 9861m.roessler Website

 
 
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Location

 

301AMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Citation

BibTex format

@article{Le:2017:10.1021/jacs.7b09261,
author = {Le, Breton N and Wright, JJ and Jones, AJY and Salvadori, E and Bridges, HR and Hirst, J and Roessler, MM},
doi = {10.1021/jacs.7b09261},
journal = {Journal of the American Chemical Society},
pages = {16319--16326},
title = {Using hyperfine electron paramagnetic resonance spectroscopy to define the proton-coupled electron transfer reaction at Fe-S cluster N2 in respiratory complex I},
url = {http://dx.doi.org/10.1021/jacs.7b09261},
volume = {139},
year = {2017}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Energy-transducing respiratory complex I (NADH:ubiquinone oxidoreductase) is one of the largest and most complicated enzymes in mammalian cells. Here, we used hyperfine electron paramagnetic resonance (EPR) spectroscopic methods, combined with site-directed mutagenesis, to determine the mechanism of a single proton-coupled electron transfer reaction at one of eight iron-sulfur clusters in complex I, [4Fe-4S] cluster N2. N2 is the terminal cluster of the enzyme's intramolecular electron-transfer chain and the electron donor to ubiquinone. Because of its position and pH-dependent reduction potential, N2 has long been considered a candidate for the elusive "energy-coupling" site in complex I at which energy generated by the redox reaction is used to initiate proton translocation. Here, we used hyperfine sublevel correlation (HYSCORE) spectroscopy, including relaxation-filtered hyperfine and single-matched resonance transfer (SMART) HYSCORE, to detect two weakly coupled exchangeable protons near N2. We assign the larger coupling with A(1H) = [-3.0, -3.0, 8.7] MHz to the exchangeable proton of a conserved histidine and conclude that the histidine is hydrogen-bonded to N2, tuning its reduction potential. The histidine protonation state responds to the cluster oxidation state, but the two are not coupled sufficiently strongly to catalyze a stoichiometric and efficient energy transduction reaction. We thus exclude cluster N2, despite its proton-coupled electron transfer chemistry, as the energy-coupling site in complex I. Our work demonstrates the capability of pulse EPR methods for providing detailed information on the properties of individual protons in even the most challenging of energy-converting enzymes.
AU  - Le,Breton N
AU  - Wright,JJ
AU  - Jones,AJY
AU  - Salvadori,E
AU  - Bridges,HR
AU  - Hirst,J
AU  - Roessler,MM
DO  - 10.1021/jacs.7b09261
EP  - 16326
PY  - 2017///
SN  - 1520-5126
SP  - 16319
TI  - Using hyperfine electron paramagnetic resonance spectroscopy to define the proton-coupled electron transfer reaction at Fe-S cluster N2 in respiratory complex I
T2  - Journal of the American Chemical Society
UR  - http://dx.doi.org/10.1021/jacs.7b09261
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000415785900047&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://pubs.acs.org/doi/10.1021/jacs.7b09261
UR  - http://hdl.handle.net/10044/1/69427
VL  - 139
ER  -
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