Mitochondrial transcription factor A (mtTFA; also designated Tfam) is necessary for both transcription and maintenance of mitochondrial DNA. mtTFA preferentially recognizes cisplatin-damaged DNA, as well as oxidized DNA. Increased apoptosis has been observed in mtTFA knockout animals, suggesting that mtTFA is involved in apoptosis. A fraction of p53 protein localizes to mitochondria at the onset of p53-dependent apoptosis, but not during p53-independent apoptosis. Using immunochemical coprecipitation, we observed binding of mtTFA and p53. Interaction between mtTFA and p53 required the high mobility group-box1 or high mobility group-box2 of mtTFA and amino acids 363-376 of p53. Binding of mtTFA to cisplatin-modified DNA was significantly enhanced by p53, whereas binding to oxidized DNA was inhibited. Our findings suggest that the interaction of p53 with mtTFA may play an important role in apoptosis.