Structural dynamics of the manganese-stabilizing protein-effect of pH, calcium, and manganese
2005 (English)In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 44, no 46, 15182-15192 p.Article in journal (Refereed) Published
The photosystem-II-associated 33-kDa extrinsic manganese-stabilizing protein is found in all oxygen-evolving organisms. In this paper, we show that this protein undergoes pH-induced conformational changes in the physiological pH range. At a neutral pH of 7.2, the hydrophobic amino acid residues that are most likely located inside the barrel are "closed" and the protein binds neither Mn2+ nor Ca2+ ions. When the protein is transferred to a solution with a slightly acidic pH of 5.7, hydrophobic amino acid residues become exposed to the surrounding medium, enabling them to bind the fluorescent probe 8,1-ANS. At this pH-induced open state, Mn2+ and Ca2+ bind to the manganese-stabilizing protein. The pH values used in this study, 7.2 and 5.7, are typical of the pH found in the thylakoid lumen in the dark and light, respectively. A model is presented in which the manganese-stabilizing protein undergoes a pH-dependent conformational change that in turn influences its capacity to bind calcium and manganese. In this model, the proton-dependent conformational changes of the tertiary structure of the manganese-stabilizing protein are of functional relevance for the regulation of substrate (water) delivery to and product (proton) release from the water-oxidizing complex by forming a proton-sensing proton-transport pathway.
Place, publisher, year, edition, pages
Easton: American Chemical Society , 2005. Vol. 44, no 46, 15182-15192 p.
Anilino Naphthalenesulfonates/chemistry, Calcium/*pharmacology, DNA; Circular, Darkness, Hydrogen-Ion Concentration, Light, Manganese/*pharmacology, Models; Chemical, Photosystem II Protein Complex/*chemistry/drug effects/radiation effects, Protein Conformation/*drug effects, Protein Folding, Spectrometry; Fluorescence
IdentifiersURN: urn:nbn:se:umu:diva-12831DOI: doi:10.1021/bi0512750PubMedID: 16285721OAI: oai:DiVA.org:umu-12831DiVA: diva2:152502