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A high redox potential form of cytochrome c550 in photosystem II from Thermosynechococcus elongatus

Opened Access A high redox potential form of cytochrome c550 in photosystem II from Thermosynechococcus elongatus

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Autor: Guerrero, Fernando Javier
Sedoud, Arezki
Kirilovsky, Diana L.
Rutherford, Alfred William
Ortega Rodríguez, José María
Roncel Gil, Mercedes
Departamento: Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular
Fecha: 2011
Publicado en: Journal of Biological Chemistry, 286 (8), 5985-5994
Tipo de documento: Artículo
Resumen: Cytochrome c550 (cyt c550) is a component of photosystem II (PSII) from cyanobacteria, red algae, and some other eukaryotic algae. Its physiological role remains unclear. In the present work, measurements of the midpoint redox potential (Em) were performed using intact PSII core complexes preparations from a histidine-tagged PSII mutant strain of the thermophilic cyanobacterium Thermosynechococcus (T.) elongatus. When redox titrations were done in the absence of redox mediators, an Em value of +200 mV was obtained for cyt c550. This value is ∼300 mV more positive than that previously measured in the presence of mediators (E m=-80 mV). The shift from the high potential form (Em=-200 mV) to the low potential form (Em=-80 mV) of cyt c550 is attributed to conformational changes, triggered by the reduction of a component of PSII that is sequestered and out of equilibrium with the medium, most likely the Mn4Ca cluster. This reduction can occur when reduced low potential redox mediators are ...
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Tamaño: 782.0Kb
Formato: PDF

URI: http://hdl.handle.net/11441/40381

DOI: http://dx.doi.org/10.1074/jbc.M110.170126

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