Mitochondrial methyltransferase which uses S-adenosyl methionine to dimethylate two highly conserved adjacent adenosine residues (A1583 and A1584) within the loop of helix 45 at the 3-prime end of 12S rRNA, thereby regulating the assembly or stability of the small subunit of the mitochondrial ribosome (PubMed:12496758, PubMed:25305075, PubMed:31251801). Also required for basal transcription of mitochondrial DNA, probably via its interaction with POLRMT and TFAM. Stimulates transcription independently of the methyltransferase activity (PubMed:11809803, PubMed:12068295, PubMed:12897151).
