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Constitutive activity of Sauromatum guttatum alternative oxidase in Schizosaccharomyces pombe implicates residues in addition to conserved cysteines in α‐keto acid activation
Author(s) -
Crichton Paul G.,
Affourtit Charles,
Albury Mary S.,
Carré Jane E.,
Moore Anthony L.
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.2004.10.107
Subject(s) - schizosaccharomyces pombe , alternative oxidase , biochemistry , isozyme , cysteine , biology , arabidopsis thaliana , amino acid , mitochondrion , yeast , mutant , enzyme , saccharomyces cerevisiae , gene
Activity of the plant mitochondrial alternative oxidase (AOX) can be regulated by organic acids, notably pyruvate. To date, only two well‐conserved cysteine residues have been implicated in this process. We report the functional expression of two AOX isozymes ( Sauromatum guttatum Sg‐AOX and Arabidopsis thaliana At‐AOX1a) in Schizosaccharomyces pombe . Comparison of the response of these two isozymes to pyruvate in isolated yeast mitochondria and disrupted mitochondrial membranes reveals that in contrast to At‐AOX1a, Sg‐AOX activity is insensitive to pyruvate and appears to be in a constitutively active state. As both of these isozymes conserve the two cysteines, we propose that such contrasting behaviour must be a direct result of differences in their amino acid sequence and have subsequently identified novel candidate residues.