Constitutive activity of Sauromatum guttatum alternative oxidase in Schizosaccharomyces pombe implicates residues in addition to conserved cysteines in alpha-keto acid activation

FEBS Lett. 2005 Jan 17;579(2):331-6. doi: 10.1016/j.febslet.2004.10.107.

Abstract

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.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Araceae / enzymology*
  • Araceae / genetics
  • Computational Biology
  • Conserved Sequence
  • Cysteine / chemistry
  • Enzyme Activation
  • Intracellular Membranes / enzymology
  • Mitochondria / enzymology
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism
  • Molecular Sequence Data
  • Oxidation-Reduction
  • Oxidoreductases / chemistry*
  • Oxidoreductases / metabolism*
  • Plant Proteins
  • Protein Conformation
  • Pyruvic Acid / pharmacology*
  • Schizosaccharomyces / enzymology*
  • Schizosaccharomyces / genetics
  • Ubiquitin / metabolism

Substances

  • Mitochondrial Proteins
  • Plant Proteins
  • Ubiquitin
  • Pyruvic Acid
  • Oxidoreductases
  • alternative oxidase
  • Cysteine