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Respiratory cytochrome c oxidase can be efficiently reduced by the photosynthetic redox proteins cytochrome c 6 and plastocyanin in cyanobacteria
Author(s) -
Navarro José A.,
Durán Raúl V.,
De la Rosa Miguel A.,
Hervás Manuel
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.05.034
Subject(s) - plastocyanin , cytochrome b6f complex , cytochrome c1 , cytochrome c oxidase , cytochrome , electron transport chain , photosystem i , cytochrome c , chemistry , cytochrome f , cytochrome b , respiratory chain , photosynthesis , electron transfer , coenzyme q – cytochrome c reductase , photochemistry , biochemistry , photosystem ii , enzyme , mitochondrion , mitochondrial dna , gene
Plastocyanin and cytochrome c 6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. Although their role as electron shuttle between the cytochrome b 6 f and photosystem I complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. Here, we present the first time‐resolved analysis showing that both cytochrome c 6 and plastocyanin can be efficiently oxidized by the aa 3 type cytochrome c oxidase in Nostoc sp. PCC 7119. The apparent electron transfer rate constants are ca. 250 and 300 s −1 for cytochrome c 6 and plastocyanin, respectively. These constants are 10 times higher than those obtained for the oxidation of horse cytochrome c by the oxidase, in spite of being a reaction thermodynamically more favourable.