Branched mitochondrial electron transport in the Animalia: presence of alternative oxidase in several animal phyla.
The mitochondrion of most eukaryotes has multiple electron transport components that increase the points of entry and/or exit of electrons, thus giving a branched nature to the respiratory chain. In plants and many other organisms, a prominent example is alternative oxidase, a non-energy conserving branch in the respiratory chain and an additional terminal oxidase for the exit of electrons. Our genome database searches have now revealed the presence of alternative oxidase in four animal species from three different phyla (Mollusca, Nematoda and Chordata), consistent with frequent reports of cyanide-resistant respiration in the Animalia. In Ciona intestinalis and Crassostrea gigas, alternative oxidase is expressed in several different tissues. Phylogenetic analysis is consistent with the animal proteins having originated by vertical inheritance. We hypothesize that alternative oxidase is likely widespread in the Animalia and discuss some of the potential role(s) for such a branched respiratory chain.
McDonald
Allison
A
Department of Life Sciences, University of Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario, Canada M1C 1A4.
Vanlerberghe
Greg
G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002938:Ciona intestinalis / Q000201:enzymology / Q000235:genetics; D004579:Electron Transport; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D024101:Mitochondrial Proteins; D010088:Oxidoreductases / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins; D016415:Sequence Alignment; D014431:Tylenchoidea / Q000201:enzymology / Q000235:genetics; D000099188:Alternative Oxidase
D024101:Mitochondrial Proteins; D010088:Oxidoreductases; D010940:Plant Proteins; D000099188:Alternative Oxidase