RPP2, AN ESSENTIAL PROTEIN SUBUNIT OF NUCLEAR RNASE-P, IS REQUIRED FOR PROCESSING OF PRECURSOR TRANSFER-RNAS AND 35S PRECURSOR RIBOSOMAL-RNA IN SACCHAROMYCES-CEREVISIAE

RPP2, an essential gene that encodes a 15.8-kDa protein subunit of nuc lear RNase P, has been identified in the genome of Saccharomyces cerev isiae. Rpp2 was detected by sequence similarity with a human protein, Rpp20, which copurifies with human RNase P. Epitope-tagged Rpp2 can be found in association with both RNase P and RNase mitochondrial RNA pr ocessing in immunoprecipitates from crude extracts of cells. Depletion of Rpp2 protein in vivo causes accumulation of precursor tRNAs with u nprocessed introns and 5' and 3' termini, and leads to defects in the processing of the 35S precursor rRNA. Rpp2-depleted cells are defectiv e in processing of the 5.8S rRNA. Rpp2 immunoprecipitates cleave both yeast precursor tRNAs and precursor rRNAs accurately at the expected s ites and contain the Rpp1 protein orthologue of the human scleroderma autoimmune antigen, Rpp30. These results demonstrate that Rpp2 is a pr otein subunit of nuclear RNase P that is functionally conserved in euk aryotes from yeast to humans.