Isolation of Mitochondrial DNA-Binding Proteins Specific to the Maize cox1 Promoter

Abstract

Proteins interacting with the promoter region of the cox1 gene have been isolated from maize mitochondria. Neither the poly[dIdC-dIdC] duplex nor KCl at concentrations up to 500 mM affect the binding, which indicates that the complex is highly specific. Moreover, no binding is observed with promoter regions of other mitochondrial genes (cox3 and rrn26). Mobility shift competition data confirm the assumption that the protein under study is specific to the cox1 promoter. The results of electrophoretic mobility shift assay (EMSA) combined with protein elution from polyacrylamide gel indicate that the DNA-protein complex contains three polypeptides with molecular weights of 60, 44, and 22 kDa. It has been shown that the core motif AAGTA is essential for DNA binding. It is proposed that the proteins under consideration play an important role in the transcription of the plant mitochondrial cox1 gene.