Mechanism of transcription initiation by the yeast mitochondrial RNA polymerase

► Mitochondrial (mt) RNA polymerases (RNAP) serve as an intriguing link between single and multi-subunit RNAPs. ► Although structurally similar to T7 RNAP, the mt RNAPs depend on accessory transcription factors. ► Both components bind the promoter and work cooperatively to catalyze promoter-specific initiation. ► Induced-fit mechanism involving DNA bending is employed to differentiate between promoter and non-promoters.