Binds promoter DNA and regulates initiation of transcription (PubMed:22784680, PubMed:24068965). Regulates mitochondrial replication and transcription (PubMed:22784680, PubMed:24068965). Required for normal topology and maintenance of mitochondrial DNA (mtDNA) levels (PubMed:22784680, PubMed:24068965). Regulates mtDNA replication by re-activating replication after replication pausing (PubMed:24068965). Likely to regulate replication pausing by coordinating with the mitochondrial termination factor mTTF which promotes replication pausing (PubMed:24068965). Their function in replication pausing prevents unregulated replication that may occur for example by collisions between the machineries of DNA replication and transcription during mtDNA synthesis (PubMed:24068965). This ensures the incorporation of RNA transcripts into replication intermediates at the replication fork and allows for proper fork progression (PubMed:24068965). Possibly functions downstream of Dref which activates genes involved in mtDNA replication and maintenance (PubMed:24068965). Probably binds to the mTTF-DNA complex. RNAi-mediated knockdown is lethal. Most mutants fail to develop past the L3 larval stage, and the few pupal escapers do not develop past the late pupal stages. Belongs to the mTERF family.