Direct assignment of EPR spectra to structurally defined iron-sulfur clusters in complex I by double electron-electron resonance

Roessler, Maxie M., King, Martin S., Robinson, Alan J., Armstrong, Fraser A., Harmer, Jeffrey and Hirst, Judy (2010) Direct assignment of EPR spectra to structurally defined iron-sulfur clusters in complex I by double electron-electron resonance. Proceedings of the National Academy of Sciences of the United States of America, 107 5: 1930-1935. doi:10.1073/pnas.0908050107


Author Roessler, Maxie M.
King, Martin S.
Robinson, Alan J.
Armstrong, Fraser A.
Harmer, Jeffrey
Hirst, Judy
Title Direct assignment of EPR spectra to structurally defined iron-sulfur clusters in complex I by double electron-electron resonance
Journal name Proceedings of the National Academy of Sciences of the United States of America   Check publisher's open access policy
ISSN 0027-8424
1091-6490
Publication date 2010-02-02
Sub-type Article (original research)
DOI 10.1073/pnas.0908050107
Volume 107
Issue 5
Start page 1930
End page 1935
Total pages 6
Place of publication Washington, United States
Publisher National Academy of Sciences
Language eng
Formatted abstract
In oxidative phosphorylation, complex I (NADH:quinone oxidoreductase) couples electron transfer to proton translocation across an energy-transducing membrane. Complex I contains a flavin mononucleotide to oxidize NADH, and an unusually long series of iron-sulfur (FeS) clusters, in several subunits, to transfer the electrons to quinone. Understanding coupled electron transfer in complex I requires a detailed knowledge of the properties of individual clusters and of the cluster ensemble, and so it requires the correlation of spectroscopic and structural data: This has proved a challenging task. EPR studies on complex I from Bos taurus have established that EPR signals N1b, N2 and N3 arise, respectively, from the 2Fe cluster in the 75 kDa subunit, and from 4Fe clusters in the PSST and 51 kDa subunits (positions 2, 7, and 1 along the seven-cluster chain extending from the flavin). The other clusters have either evaded detection or definitive signal assignments have not been established. Here, we combine double electron-electron resonance (DEER) spectroscopy on B. taurus complex I with the structure of the hydrophilic domain of Thermus thermophilus complex I. By considering the magnetic moments of the clusters and the orientation selectivity of the DEER experiment explicitly, signal N4 is assigned to the first 4Fe cluster in the TYKY subunit (position 5), and N5 to the all-cysteine ligated 4Fe cluster in the 75 kDa subunit (position 3). The implications of our assignment for the mechanisms of electron transfer and energy transduction by complex I are discussed.
Keyword Deer
Distance measurement
Mitochondria
NADH:quinone oxidoreductase
Pulsed EPR
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Advanced Imaging Publications
 
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