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Enzymatic activity of the alternative complex III as a menaquinol:auracyanin oxidoreductase in the electron transfer chain of Chloroflexus aurantiacus
Author(s) -
Gao Xinliu,
Xin Yueyong,
Blankenship Robert E.
Publication year - 2009
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.2009.09.022
Subject(s) - cytochrome , anoxygenic photosynthesis , oxidoreductase , chemistry , electron transfer , electron acceptor , electron transport chain , coenzyme q – cytochrome c reductase , enzyme , biochemistry , cytochrome c , stereochemistry , phototroph , photochemistry , mitochondrion , photosynthesis
The surprising lack of the cytochrome bc 1 complex in the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus suggests that a functional replacement exists to link the cyclic electron transfer chain. Earlier work identified the alternative complex III (ACIII) as a substitute of cytochrome bc 1 complex. Herein, the enzymatic activity of ACIII is studied. The results strongly support the view that the ACIII functions as menaquinol:auracyanin oxidoreductase in the C. aurantiacus electron transfer chain. Among all the substrates tested, auracyanin is the most efficient electron acceptor of ACIII, suggesting that ACIII directly transfers the electron to auracyanin instead of cytochrome c ‐554. The lack of sensitivity to common inhibitors of the cytochrome bc 1 complex indicates a different catalytic mechanism for the ACIII complex.