title: Increased tolerance to thermal inactivation of oxygen evolution in spinach Photosystem II membranes by substitution of the extrinsic 33-kDa protein by its homologue from a thermophilic cyanobacterium.
abstract: Photosynthetic oxygen evolution is an extremely heat-sensitive process and incubation of spinach Photosystem II (PSII) membranes at 40 degrees C for only several minutes leads to its complete inactivation. Substitution experiments of the spinach 33-kDa manganese stabilizing protein by a homologue protein, isolated either from the thermophilic cyanobacterium Phormidium laminosum, or from Escherichia coli as a recombinant thermophilic cyanobacterial protein, showed a significant increase in tolerance to heat inactivation of the oxygen-evolving activity. The results allow us to suggest that thermal inactivation of oxygen evolution in higher plant PSII membranes is due to dissociation of the 33-kDa protein as a consequence of temperature-induced conformational changes, and stabilization can be provided by substitution by a thermostable homologue whose secondary structure and binding to PSII remain unaltered at moderately high temperatures.
authors.affiliation: Estación Experimental de Aula Dei (CSIC), Apdo. 202, E-50080 Zaragoza, Spain. pueyo@ccma.csic.es
authors.forename: José J
authors.initials: JJ
authors.lastname: Pueyo
authors.forename: Miguel
authors.initials: M
authors.lastname: Alfonso
authors.forename: Carmen
authors.initials: C
authors.lastname: Andrés
authors.forename: Rafael
authors.initials: R
authors.lastname: Picorel
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology; D000458:Cyanobacteria; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D010100:Oxygen / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism; D018724:Spinacia oleracea; D013329:Structure-Activity Relationship
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011506:Proteins; C054266:photosystem II manganese-stabilizing protein; D012697:Serine Endopeptidases; C036813:lysyl endopeptidase; D002122:Calcium Chloride; D010100:Oxygen