Adenine nucleotide-dependent and redox-independent control of mitochondrial malate dehydrogenase activity in Arabidopsis thaliana.

摘要: Mitochondrial metabolism is important for sustaining cellular growth and maintenance; however, the regulatory mechanisms underlying individual processes in plant mitochondria remain largely uncharacterized. Previous redox-proteomics studies have suggested that mitochondrial malate dehydrogenase (mMDH), a key enzyme tricarboxylic acid (TCA) cycle redox shuttling, under thiol-based regulation as target candidate of thioredoxin (Trx). In addition, adenine nucleotide status may be another factor controlling metabolism, respiratory ATP production believed to influenced by several environmental stimuli. Using biochemical reverse-genetic approaches, we addressed redox- nucleotide-dependent mMDH Arabidopsis thaliana. Recombinant protein formed intramolecular disulfide bonds oxidative conditions, but these did not considerable effect on activity. Mitochondria-localized o-type Trx (Trx-o) facilitate re-reduction oxidized mMDH. Determination vivo state revealed was stably present reduced form even Trx-o-deficient plants. Accordingly, concluded class redox-regulated enzymes. By contrast, activity lowered nucleotides (AMP, ADP, ATP). Each suppressed with different potencies exerted largest inhibitory significantly lower K(I). Correspondingly, inhibited increase ATP/ADP ratio within physiological range. These results suggest finely controlled response variations balance.