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1.
Biochim Biophys Acta ; 1837(9): 1447-53, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24388917

RESUMO

The PsbP protein is an extrinsic subunit of photosystem II (PSII) that is essential for photoautotrophic growth in higher plants. Several crystal structures of PsbP have been reported, but the binding topology of PsbP in PSII has not yet been clarified. In this study, we report that the basic pocket of PsbP, which consists of conserved Arg48, Lys143, and Lys160, is important for the electrostatic interaction with the PSII complex. Our release-reconstitution experiment showed that the binding affinities of PsbP-R48A, -K143A, and -K160A mutated proteins to PSII were lower than that of PsbP-WT, and triple mutations of these residues greatly diminished the binding affinity to PSII. Even when maximum possible binding had occurred, the R48A, K143A, and K160A proteins showed a reduced ability to restore the rate of oxygen evolution at low chloride concentrations. Fourier transform infrared resonance (FTIR) difference spectroscopy results were consistent with the above finding, and suggested that these mutated proteins were not able to induce the normal conformational change around the Mn cluster during S1 to S2 transition. Finally, chemical cross-linking experiments suggested that the interaction between the N-terminus of PsbP with PsbE was inhibited by these mutations. These data suggest that the basic pocket of PsbP is important for proper association and interaction with PSII. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy.


Assuntos
Complexo de Proteína do Fotossistema II/química , Eletricidade Estática , Cloretos/química , Modelos Moleculares , Mutação , Estrutura Terciária de Proteína , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Biochemistry ; 52(34): 5705-7, 2013 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-23937307

RESUMO

Effects of binding of extrinsic proteins (PsbO, PsbQ', PsbV, and PsbU) on the structure of the oxygen-evolving center (OEC) in photosystem II core complexes from a red alga, Cyanidium caldarium, were studied using Fourier transform infrared (FTIR) spectroscopy. S2-minus-S1 FTIR difference spectra showed that the protein conformations of the OEC, revealed by the changes in amide I and II bands, were significantly altered upon depletion of all the extrinsic proteins, but mostly recovered when PsbV was rebound with the support of other extrinsic proteins. The recovery of protein conformations correlated well with O2 evolution activity. This PsbV function of retaining a proper OEC conformation in red algae resembles that of PsbP in higher plants reported previously.


Assuntos
Proteínas de Algas/metabolismo , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/metabolismo , Conformação Proteica , Rodófitas , Espectroscopia de Infravermelho com Transformada de Fourier
3.
J Biol Chem ; 287(31): 26377-87, 2012 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-22707728

RESUMO

The PsbP protein regulates the binding properties of Ca(2+) and Cl(-), and stabilizes the Mn cluster of photosystem II (PSII); however, the binding site and topology in PSII have yet to be clarified. Here we report that the structure around His-144 and Asp-165 in PsbP, which is suggested to be a metal binding site, has a crucial role for the functional interaction between PsbP and PSII. The mutated PsbP-H144A protein exhibits reduced ability to retain Cl(-) anions in PSII, whereas the D165V mutation does not affect PsbP function. Interestingly, H144A/D165V double mutation suppresses the effect of H144A mutation, suggesting that these residues have a role other than metal binding. FTIR difference spectroscopy suggests that H144A/D165V restores proper interaction with PSII and induces the conformational change around the Mn cluster during the S(1)/S(2) transition. Cross-linking experiments show that the H144A mutation affects the direct interaction between PsbP and the Cyt b(559) α subunit of PSII (the PsbE protein). However, this interaction is restored in the H144A/D165V mutant. In the PsbP structure, His-144 and Asp-165 form a salt bridge. H144A mutation is likely to disrupt this bridge and liberate Asp-165, inhibiting the proper PsbP-PSII interaction. Finally, mass spectrometric analysis has identified the cross-linked sites of PsbP and PsbE as Ala-1 and Glu-57, respectively. Therefore His-144, in the C-terminal domain of PsbP, plays a crucial role in maintaining proper N terminus interaction. These data provide important information about the binding characteristics of PsbP in green plant PSII.


Assuntos
Histidina/química , Complexo de Proteína do Fotossistema II/química , Subunidades Proteicas/química , Spinacia oleracea , Motivos de Aminoácidos , Substituição de Aminoácidos , Cálcio/química , Carbodi-Imidas/química , Cloretos/química , Simulação por Computador , Sequência Conservada , Reagentes de Ligações Cruzadas/química , Histidina/genética , Cinética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Oxigênio/química , Fragmentos de Peptídeos/química , Complexo de Proteína do Fotossistema II/genética , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Subunidades Proteicas/genética , Espectroscopia de Infravermelho com Transformada de Fourier
4.
Biochim Biophys Acta ; 1817(8): 1346-51, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22306528

RESUMO

PsbP and PsbQ proteins are extrinsic subunits of photosystem II (PSII) and optimize the oxygen evolution reaction by regulating the binding properties of the essential cofactors Ca(2+) and Cl(-). PsbP induces conformational changes around the catalytic Mn cluster required for Ca(2+) and Cl(-) retention, and the N-terminal region of PsbP is essential for this reaction. It was reported that PsbQ partially restores the functional defect of N-terminal truncated PsbP [Ifuku and Sato (2002) Plant Cell Physiol. 43, 1244-1249]; however, the mechanism of this restoration is yet to be clarified. In this study, we demonstrate that PsbQ is able to restore the functional binding of mutated PsbPs. In the presence of PsbQ, ∆15-PsbP, a truncated PsbP lacking 15 N-terminal residues, was able to specifically bind to NaCl-washed spinach PSII membranes and significantly restore the oxygen evolving activity. Furthermore, PsbQ was also able to compensate for the impaired ion-retention of H144A-PsbP, in which a conserved histidine at position 144 in the C-terminal domain was substituted with an alanine. Fourier transform infrared (FTIR) difference spectroscopy showed that PsbQ restored the ability of ∆15- and H144A-PsbP to induce proper conformational changes during S(1) to S(2) transition. These data suggest that the major function of PsbQ is to stabilize PsbP binding, thereby contributing to the maintenance of the catalytic Mn cluster of the water oxidation machinery in higher plant PSII. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.


Assuntos
Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/fisiologia , Proteínas de Plantas/química , Proteínas de Plantas/fisiologia , Spinacia oleracea/metabolismo , Conformação Proteica , Subunidades Proteicas/química , Espectroscopia de Infravermelho com Transformada de Fourier
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