caa a22 4500 445889993 CHVBK 20180317145613.0 cr unu---uuuuu 170323e20111201xx s 000 0 eng 10.1007/s11120-011-9703-8 doi (NATIONALLICENCE)springer-10.1007/s11120-011-9703-8 Probing the topography of the photosystem II oxygen evolving complex: PsbO is required for efficient calcium protection of the manganese cluster against dark-inhibition by an artificial reductant [Elektronische Daten] [Hana Popelkova, Nicholas Boswell, Charles Yocum] The photosystem II (PSII) manganese-stabilizing protein (PsbO) is known to be the essential PSII extrinsic subunit for stabilization and retention of the Mn and Cl− cofactors in the oxygen evolving complex (OEC) of PSII, but its function relative to Ca2+ is less clear. To obtain a better insight into the relationship, if any, between PsbO and Ca2+ binding in the OEC, samples with altered PsbO-PSII binding properties were probed for their potential to promote the ability of Ca2+ to protect the Mn cluster against dark-inhibition by an exogenous artificial reductant, N,N-dimethylhydroxylamine. In the absence of the PsbP and PsbQ extrinsic subunits, Ca2+ and its surrogates (Sr2+, Cd2+) shield Mn atoms from inhibitory reduction (Kuntzleman et al., Phys Chem Chem Phys 6:4897, 2004). The results presented here show that PsbO exhibits a positive effect on Ca2+ binding in the OEC by facilitating the ability of the metal to prevent inhibition of activity by the reductant. The data presented here suggest that PsbO may have a role in the formation of the OEC-associated Ca2+ binding site by promoting the equilibrium between bound and free Ca2+ that favors the bound metal. Springer Science+Business Media B.V., 2011 Calcium nationallicence Manganese reduction nationallicence Manganese-stabilizing protein nationallicence Mutation nationallicence Photosystem II nationallicence BSA : Bovine serum albumin nationallicence DCBQ : 2,6-Dichloro-1,4-benzoquinone nationallicence DMHA : N,N-Dimethylhydroxylamine nationallicence EDTA : (Ethylenedinitrilo)tetraacetic acid disodium salt nationallicence EXFAS : Extended X-ray absorption fine structure nationallicence MES : 2-(N-Morpholino)ethanesulfonic acid nationallicence PsbO : Manganese-stabilizing protein nationallicence OEC : Oxygen-evolving complex nationallicence PS : Photosystem II nationallicence SW-PSII : NaCl-washed photosystem II membranes depleted of 23 and 17kDa extrinsic proteins nationallicence UW-PSII : Urea NaCl-washed photosystem II membranes depleted of PsbO, PsbP, and PsbQ (33, 23, and 17kDa) extrinsic proteins nationallicence WT : Wild-type PsbO nationallicence Popelkova Hana Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut Boswell Nicholas Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut Yocum Charles Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut Photosynthesis Research Springer Netherlands 110/2(2011-12-01), 111-121 0166-8595 110:2<111 2011 110 11120 https://doi.org/10.1007/s11120-011-9703-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11120-011-9703-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Popelkova Hana Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut NATIONALLICENCE 700 1- Boswell Nicholas Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut NATIONALLICENCE 700 1- Yocum Charles Department of Molecular, Cellular, and Developmental Biology, The University of Michigan, 48109-1048, Ann Arbor, MI, USA aut NATIONALLICENCE 773 0- Photosynthesis Research Springer Netherlands 110/2(2011-12-01), 111-121 0166-8595 110:2<111 2011 110 11120 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer