Involvement of the alternative oxidase in respiration of Yarrowia lipolytica mitochondria is controlled by the activity of the cytochrome pathway.
The degree of involvement of cyanide-resistant alternative oxidase in the respiration of Yarrowia lipolytica mitochondria was evaluated by comparing the rate of oxygen consumption in the presence of cyanide, which shows the activity of the cyanide-resistant alternative oxidase, and the oxidation rate of cytochrome c by ferricyanide, which shows the activity of the main cytochrome pathway. The oxidation of succinate by mitochondria in the presence of ferricyanide and cyanide was associated with oxygen consumption due to the functioning of the alternative oxidase. The subsequent addition of ADP or FCCP (an uncoupler of oxidative phosphorylation) completely inhibited oxygen consumption by the mitochondria. Under these conditions, the inhibition of the alternative oxidase by benzohydroxamic acid (BHA) failed to affect the reduction of ferricyanide at the level of cytochrome c. BHA did not influence the rate of ferricyanide reduction by the cytochrome pathway occurring in controlled state 4, nor could it change the phosphorylation quotient ATP/O upon the oxidation of various substrates. These data indicate that the alternative system is unable to compete with the cytochrome respiratory chain for electrons. The alternative oxidase only transfers the electrons that are superfluous for the cytochrome respiratory chain.
Medentsev
Aleksandr G
AG
Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, Pushchino, Moscow region 142290, Russia.
Arinbasarova
Anna Yu
AY
Golovchenko
Nikolai P
NP
Akimenko
Vassily K
VK
D003580:Cytochromes / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D024101:Mitochondrial Proteins; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010088:Oxidoreductases / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010940:Plant Proteins; D011190:Potassium Cyanide / Q000494:pharmacology; D025062:Yarrowia / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D000099188:Alternative Oxidase
D003580:Cytochromes; D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D011190:Potassium Cyanide; D000099188:Alternative Oxidase