title: Nitric oxide-induced formation of the S-2 state in the oxygen-evolving complex of photosystem II from Synechococcus elongatus.
abstract: In spinach photosystem II (PSII) membranes, the tetranuclear manganese cluster of the oxygen-evolving complex (OEC) can be reduced by incubation with nitric oxide at -30 degrees C to a state which is characterized by an Mn(2)(II, III) EPR multiline signal [Sarrou, J., Ioannidis, N., Deligiannakis, Y., and Petrouleas, V. (1998) Biochemistry 37, 3581-3587]. This state was recently assigned to the S(-)(2) state of the OEC [Schansker, G., Goussias, C., Petrouleas, V., and Rutherford, A. W. (2002) Biochemistry 41, 3057-3064]. On the basis of EPR spectroscopy and flash-induced oxygen evolution patterns, we show that a similar reduction process takes place in PSII samples of the thermophilic cyanobacterium Synechococcus elongatus at both -30 and 0 degrees C. An EPR multiline signal, very similar but not identical to that of the S(-)(2) state in spinach, was obtained with monomeric and dimeric PSII core complexes from S. elongatus only after incubation at -30 degrees C. The assignment of this EPR multiline signal to the S(-)(2) state is corroborated by measurements of flash-induced oxygen evolution patterns and detailed fits using extended Kok models. The small reproducible shifts of several low-field peak positions of the S(-)(2) EPR multiline signal in S. elongatus compared to spinach suggest that slight differences in the coordination geometry and/or the ligands of the manganese cluster exist between thermophilic cyanobacteria and higher plants.
authors.affiliation: Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany. isarrou@ucdavis.edu
authors.forename: Josephine
authors.initials: J
authors.lastname: Sarrou
authors.forename: Sabina
authors.initials: S
authors.lastname: Isgandarova
authors.forename: Jan
authors.initials: J
authors.lastname: Kern
authors.forename: Athina
authors.initials: A
authors.lastname: Zouni
authors.forename: Gernot
authors.initials: G
authors.lastname: Renger
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lubitz
authors.forename: Johannes
authors.initials: J
authors.lastname: Messinger
mesh_terms: D002412:Cations / Q000737:chemistry; D000458:Cyanobacteria / Q000737:chemistry* / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D008345:Manganese / Q000737:chemistry; D008956:Models, Chemical; D009569:Nitric Oxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D010782:Photolysis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D013059:Spectrum Analysis, Raman; D018724:Spinacia oleracea; D020524:Thylakoids / Q000737:chemistry / Q000378:metabolism
chemical_list: D002412:Cations; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D009569:Nitric Oxide; D008345:Manganese; D010100:Oxygen