Purification of mitochondrial RNA polymerase from Saccharomyces cerevisiae

Abstract

The RNA polymerase from the mitochondria of Saccharomyces cerevisiae has been extensively purified by Sepharose 4B, heparin Sepharose 4B phosphocellulose, and DEAE-Sephadex A-50 chromatography. The activity co-sediments with a 45,000-dalton polypeptide at 6.3 S in glycerol gradients. The activity is inhibited by antibodies to the 45,000-dalton polypeptide. The activity is not inhibited by rifampicin or alpha-amanitin. It requires Mg2+ and is inhibited by elevated ionic strength and Mn2+. The most efficient template for the RNA polymerase is poly[d(AT)], with mtDNA being the preferred natural template. The RNA polymerase transcribes mtDNA from the petite strain F11 in a nonrandom manner.