Redox Modification and Phosphorylation Modulate the Activity of the Mitochondrial DNA-Binding Protein Complex Specific for the Maize coxl Promoter

摘要

Phosphorylation and modification of redox-sensi-tive Cys residues are the most common mechanisms regulating the activity of proteins.Many events of the genetic regulation of cell processes are controlled by physiological redox homeostasis and,especially,the thiol-disulfide balance [1,2].Since oxidation and reduction continuously proceed in mitochondria and are accompanied by changes in redox potential,it is reasonable to assume that the redox balance regulates the mitochondrial gene expression.A dependence of mitochondrial RNA synthesis on the redox balance and,in particular,the glutathione redox system,has already been reported for higher plants [3,4].However,the molecular mechanism of redox regulation of mitochondrial gene expression in vivo is unclear.Protein phosphorylation is also involved in regulating the genetic functions in mitochondria,which is evident from changes in RNA synthesis in isolated mitochondria in the presence of protein kinase and protein phosphatase inhibitors [3,4].The protein targets that undergo these two modifications and play a role in regulating gene expression in mitochondria have not been identified as of yet.We have previously isolated a maize mitochondrial DNA-binding protein complex (mtDBPC),which interacts with the coxl promoter but lacks affinity for the promoters of other mitochondrial genes (cox3 and rrn26) [5].We have assumed that mtDBPC plays an important role in regulating mitochondrial transcription.The objective of this work was to check whether phosphorylation and redox modification regulate the mtDBPC activity.