A Gene Required for RNase P Activity in Candida (Torulopsis) glabrata Mitochondria Codes for a 227-Nucleotide RNA with Homology to Bacterial RNase P RNA

Abstract

We have mapped a gene in the mitochondrial DNA of Candida (Torulopsis) glabrata and shown that it is required for 5′ end maturation of mitochondrial tRNAs. It is located between the tRNA^Met_i and tRNA^Pro genes, the same tRNA genes that flank the mitochondrial RNase P RNA gene in the yeast Saccharomyces cerevisiae. The gene is extremely AT rich and codes for AU-rich RNAs that display some sequence homology with the mitochondrial RNase P RNA from S. cerevisiae, including two regions of striking sequence homology between the mitochondrial RNAs and the bacterial RNase P RNAs. RNase P activity that is sensitive to micrococcal nuclease has been detected in mitochondrial extracts of C. glabrata. An RNA of 227 nucleotides that is one of the RNAs encoded by the gene that we mapped cofractionated with this mitochondrial RNase P activity on glycerol gradients. The nuclease sensitivity of the activity, the cofractionation of the RNA with activity, and the homology of the RNA with known RNase P RNAs lead us to propose that the 227-nucleotide RNA is the RNA subunit of the C. glabrata mitochondrial RNase P enzyme.