Transcriptional activation by mitochondrial transcription factor A involves preferential distortion of promoter DNA.

Mitochondrial transcription factor A (mtTFA/TFAM) is a nucleus-encoded, high-mobility-group-box (HMG-box) protein that regulates transcription of the mitochondrial genome by specifically recognizing light-strand and heavy-strand promoters (LSP, HSP1). TFAM also binds mitochondrial DNA in a non-sequence specific (NSS) fashion and facilitates its packaging into nucleoid structures. However, the requirement and contribution of DNA-bending for these two different binding modes has not been addressed in detail, which prompted this comparison of binding and bending properties of TFAM on promoter and non-promoter DNA.