Abstract
Ribonuclease mitochondrial RNA processing (RNase MRP) is a multifunctional ribonucleoprotein (RNP) complex that is involved in the maturation of various types of RNA including ribosomal RNA. RNase MRP consists of a potential catalytic RNA and several protein components, all of which are required for cell viability. We show here that the temperature-sensitive mutant of rmp1, the gene for a unique protein component of RNase MRP, accumulates the dimeric tRNA precursor, pre-tRNASer-Met. To examine whether RNase MRP mediates tRNA maturation, we purified the RNase MRP holoenzyme from the fission yeast Schizosaccharomyces pombe and found that the enzyme directly and selectively cleaves pre-tRNASer-Met, suggesting that RNase MRP participates in the maturation of specific tRNA in vivo. In addition, mass spectrometry–based ribonucleoproteomic analysis demonstrated that this RNase MRP consists of one RNA molecule and 11 protein components, including a previously unknown component Rpl701. Notably, limited nucleolysis of RNase MRP generated an active catalytic core consisting of partial mrp1 RNA fragments, which constitute “Domain 1” in the secondary structure of RNase MRP, and 8 proteins. Thus, the present study provides new insight into the structure and function of RNase MRP.
Highlights
Ribonuclease mitochondrial RNA processing (RNase MRP) is an essential eukaryotic ribonucleoprotein complex, generally consisting of one noncoding RNA and several protein subunits [1,2,3]
We tried to isolate a fission yeast (S. pombe) ts mutant caused by mutation in Rmp1, a protein subunit specific to RNase MRP
KA18 exhibited a 6-fold increase in the level of the long form of the 5.8S (5.8SL) ribosomal RNAs (rRNAs) compared with the wild-type strain. This is consistent with previous reports that 5.8SL rRNA accumulates in the ts strain that has a mutation in mrp1 RNA or Rmp1/Snm1 protein owing to the reduced cellular activity of RNase MRP to cleave site A3 [19,53,54,55,56], indicating that KA18 has a defect in RNase MRP activity
Summary
Ribonuclease mitochondrial RNA processing (RNase MRP) is an essential eukaryotic ribonucleoprotein complex, generally consisting of one noncoding RNA (ncRNA) and several protein subunits [1,2,3]. The multisubunit composition of RNase MRP is remarkably similar to that of RNase P [1,2,15,16]. In Saccharomyces cerevisiae, RNase MRP contains a 340 nt–long RNA component and ten essential proteins (listed in Table S1), eight of which are shared with RNase P [17]. Human RNase MRP and P have similar subunit compositions (Table S1) [20,21,22]
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