RNase MRP is a ribonucleoprotein particle (RNP) with endoribonucleolytic activity which is involved in the processing of pre-rRNA at site A<SUB>3</SUB>. A genetic screen for mutants which are synthetic lethal (sl) with a temperature sensitive (ts) mutation in the RNA component of RNase MRP (<I>rrp2-1</I>) has been performed in order to identify new gene products which physically and/or functionally interact with RNase MRP. Analysis of the obtained sl mutant strains led to the identification of a new and essential gene, <I>POP3</I>. Depletion of Pop3p <I>in vivo</I> results in a phenotype characteristic of the loss of RNase MRP activity; A<SUB>3</SUB> cleavage is inhibited, leading to under-accumulation of the short form of the 5.8S rRNA (5.8S<SUB>S</SUB>) and formation of an aberrant 5.8S rRNA precursor which is 5' extended to site A<SUB>2</SUB>. Pop3p depletion also inhibits pre-tRNA processing. Primary tRNA transcripts accumulate, as well as spliced but 5' and 3' unprocessed pre-tRNAs. The Pop3p depletion phenotypes resemble those previously described for mutations in components of RNase MRP and RNase P (<I>rrp2-1, rpr1-1 </I>and <I>pop1-1</I>). Immunoprecipitation of epitope tagged Pop3p efficiently co-precipitates the RNA components of both RNase MRP and RNase P. Thus, Pop3p is a common component of both RNPs and is required for the function of both enzymes <I>in vivo</I>. Strain SL158 carried a mutation in <I>HAL2</I> which is sl in combination with <I>rrp2-1. </I>Hal2p is an enzyme that converts pAp (adenosine 3', 5' bisphosphate), a product of sulfate assimilation, into 5' AMP and P<SUB>i</SUB>.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649515 |
| Date | January 1998 |
| Creators | Dichtl, Bernhard |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13645 |
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