Electronic structure of the oxygen evolving complex in photosystem II, as revealed by 55Mn Davies ENDOR studies at 2.5 K

Jin, Lu, Smith, Paul, Noble, Christopher J., Stranger, Rob, Hanson, Graeme R. and Pace, Ron J. (2014) Electronic structure of the oxygen evolving complex in photosystem II, as revealed by 55Mn Davies ENDOR studies at 2.5 K. Physical Chemistry Chemical Physics, 16 17: 7799-7812. doi:10.1039/c3cp55189j


Author Jin, Lu
Smith, Paul
Noble, Christopher J.
Stranger, Rob
Hanson, Graeme R.
Pace, Ron J.
Title Electronic structure of the oxygen evolving complex in photosystem II, as revealed by 55Mn Davies ENDOR studies at 2.5 K
Journal name Physical Chemistry Chemical Physics   Check publisher's open access policy
ISSN 1463-9076
1463-9084
Publication date 2014-05-07
Year available 2014
Sub-type Article (original research)
DOI 10.1039/c3cp55189j
Open Access Status DOI
Volume 16
Issue 17
Start page 7799
End page 7812
Total pages 14
Place of publication Cambridge, United Kingdom
Publisher R S C Publications
Collection year 2015
Language eng
Subject 1606 Political Science
3100 Physics and Astronomy
Abstract We report the first 55Mn pulsed ENDOR studies on the S 2 state multiline spin centre of the oxygen evolving complex (OEC) in Photosystem II (PS II), at temperatures below 4.2 K. These were performed on highly active samples of spinach PS II core complexes, developed previously in our laboratories for photosystem spectroscopic use, at temperatures down to 2.5 K. Under these conditions, relaxation effects which have previously hindered observation of most of the manganese ENDOR resonances from the OEC coupled Mn cluster are suppressed. 55Mn ENDOR hyperfine couplings ranging from ∼50 to ∼680 MHz are now seen on the S2 state multiline EPR signal. These, together with complementary high resolution X-band CW EPR measurements and detailed simulations, reveal that at least two and probably three Mn hyperfine couplings with large anisotropy are seen, indicating that three MnIII ions are likely present in the functional S2 state of the enzyme. This suggests a low oxidation state paradigm for the OEC (mean Mn oxidation level 3.0 in the S1 state) and unexpected Mn exchange coupling in the S2 state, with two Mn ions nearly magnetically silent. Our results rationalize a number of previous ligand ESEEM/ENDOR studies and labelled water exchange experiments on the S2 state of the photosystem, in a common picture which is closely consistent with recent photo-assembly (Kolling et al., Biophys. J. 2012, 103, 313-322) and large scale computational studies on the OEC (Gatt et al., Angew. Chem., Int. Ed. 2012, 51, 12025-12028, Kurashige et al. Nat. Chem. 2013, 5, 660-666).
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
Centre for Advanced Imaging Publications
 
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