Acanthamoeba castellanii; alternative oxidase; cytochrome pathway; mitochondria; osidative phosphorylation
Abstract :
[en] The steady-state activity of the two quinol-oxidizing pathways of Acanthamoeba castellanii mitochondria, the phosphorylating cytochrome pathway (i.e. the benzohydroxamate(BHAM)-resistant respiration in state 3) and the alternative oxidase (i.e. the KCN-resistant respiration), is shown to be fixed by ubiquinone (Q) pool redox state independently of the reducing substrate (succinate or exogenous reduced nicotinamide adenine dinucleotide (NADH)), indicating that the active Q pool is homogenous. For both pathways, activity increases with the Q reduction level (up to 80%). However, the cytochrome pathway respiration partially inhibited (about 50%) by myxothiazol decreases when the Q reduction level increases above 80%. The decrease can be explained by the Q cycle mechanism of complex III. It is also shown that BHAM has an influence on the relationship between the rate of ADP phosphorylation and the Q reduction level when alternative oxidase is active, and that KCN has an influence on the relationship between the alternative oxidase activity and the Q reduction level. These unexpected effects of BHAM and KCN observed at a given Q reduction level are likely due to functional connections between the two pathways activities or to protein-protein interaction.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Jarmuszkiewicz, Wieslawa ; Université de Liège - ULiège
Sluse, Francis ; Université de Liège - ULiège > Département des sciences de la vie > Bioénergétique et physiologie cellulaire
Hryniewiecka, L.
Sluse-Goffart, Claudine; Université de Liège - ULiège
Language :
English
Title :
Interactions between the cytochrome pathway and the alternative oxidase in isolated Acanthamoeba castellanii mitochondria.
Publication date :
2002
Journal title :
Journal of Bioenergetics and Biomembranes
ISSN :
0145-479X
eISSN :
1573-6881
Publisher :
Kluwer Academic/Plenum Publishers, New York, United States - New York