title: Does histidine 332 of the D1 polypeptide ligate the manganese cluster in photosystem II? An electron spin echo envelope modulation study.
abstract: The tetranuclear manganese cluster in photosystem II is ligated by one or more histidine residues, as shown by an electron spin echo envelope modulation (ESEEM) study conducted with [(15)N]histidine-labeled photosystem II particles isolated from the cyanobacterium Synechocystis sp. strain PCC 6803 [Tang, X.-S., Diner, B. A., Larsen, B. S., Gilchrist, M. L., Jr., Lorigan, G. A., and Britt, R. D. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 704-708]. One of these residues may be His332 of the D1 polypeptide. Photosystem II particles isolated from the Synechocystis mutant D1-H332E exhibit an altered S(2) state multiline EPR signal that has more hyperfine lines and narrower splittings than the corresponding signal in wild-type PSII particles [Debus, R. J., Campbell, K. A., Peloquin, J. M., Pham, D. P., and Britt, R. D. (2000) Biochemistry 39, 470-478]. These D1-H332E PSII particles are also unable to advance beyond an altered S(2)Y(Z)(*) state, and the quantum yield for forming the S(2) state is very low, corresponding to an 8000-fold slowing of the rate of Mn oxidation by Y(Z)(*). These observations are consistent with His332 being close to the Mn cluster and modulating the redox properties of both the Mn cluster and tyrosine Y(Z). To determine if D1-His332 ligates the Mn cluster, we have conducted an ESEEM study of D1-H332E PSII particles. The histidyl nitrogen modulation observed near 5 MHz in ESEEM spectra of the S(2) state multiline EPR signal of wild-type PSII particles is substantially diminished in D1-H332E PSII particles. This result is consistent with ligation of the Mn cluster by D1-His332. However, alternate explanations are possible. These are presented and discussed.
authors: Department of Biochemistry, University of California, Riverside, California 92521-0129, USA. debusrj@citrus.ucr.edu
authors: R J
authors: RJ
authors: Debus
authors: K A
authors: KA
authors: Campbell
authors: W
authors: W
authors: Gregor
authors: Z L
authors: ZL
authors: Li
authors: R L
authors: RL
authors: Burnap
authors: R D
authors: RD
authors: Britt
mesh_terms: D000458:Cyanobacteria / Q000235:genetics / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005609:Free Radicals / Q000378:metabolism; D006639:Histidine / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008345:Manganese / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D018724:Spinacia oleracea; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D005609:Free Radicals; D008024:Ligands; D010455:Peptides; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit; C114979:tyrosyl radical YZ; D014443:Tyrosine; D008345:Manganese; D006639:Histidine