THE RNA OF RNASE MRP IS REQUIRED FOR NORMAL PROCESSING OF RIBOSOMAL-RNA

We have isolated clones which complement the temperature sensitivity a nd abnormal rRNA processing pattern of the rrp2-2 mutant of Saccharomy ces cerevisiae we previously described. DNA sequencing and restriction analysis demonstrated that all clones contain the NME1 gene encoding the RNA of the ribonucleoprotein particle RNase MRP. Deletion analysis showed that the NME1 gene is responsible for the complementation of t he rrp2-2 phenotype. A single base change was identified in the nme1 g ene in the rrp2 mutant, confirming that the RRP2 and NME1 genes are id entical. Our experiments therefore indicate that RNase MRP, in additio n to its previously reported role in formation of RNA primers for mito chondrial DNA replication [Clayton, D. A. (1991) Trends Biochem. Sci. 16, 107-111], is involved in rRNA processing.