Induction of Arabidopsis gdh2 gene expression during changes in redox state of the mitochondrial respiratory chain.

Expression of the gdh2 gene encoding the alpha-subunit of mitochondrial glutamate dehydrogenase depends on redox state of the mitochondrial electron transport chain. Treatment of Arabidopsis thaliana cell suspension with antimycin A, a respiratory chain complex III inhibitor, resulted in an increase in gdh2 transcripts within 2 h. Inhibition of complex I by rotenone did not influence the transcript level, but treatment with potassium cyanide, a complex IV inhibitor, also increased the transcript content. Thus, gdh2 gene expression obviously responds to changes in the respiratory chain segment localized between complexes I and III. Lack of activation of gene expression after treatment of a cell suspension with hydrogen peroxide and the prooxidant paraquat and results of experiments with antioxidants suggest that gdh2 gene expression is not associated with increased content of reactive oxygen species generated during inhibition of the electron transport chain. Protein phosphorylation by serine/threonine protein kinases is the essential step required for signal transduction into nucleus resulting in the induction of gdh2 expression.