Mitochondrial RNA polymerase; single subunit enzyme similar to those of T3 and T7 bacteriophages; requires a specificity subunit encoded by MTF1 for promoter recognition; Mtf1p interacts with and stabilizes the Rpo41p-promoter complex, enhancing DNA bending and melting to facilitate pre-initiation open complex formation; synthesizes RNA primers for mitochondrial DNA replication; capable of DNA-primed RNA extension, resulting in 5' input DNA with extended RNA on the 3' end