The MRPP1/MRPP2 complex is a tRNA-maturation platform in human mitochondria

Nucleic Acids Res. 2017 Dec 1;45(21):12469-12480. doi: 10.1093/nar/gkx902.


Mitochondrial polycistronic transcripts are extensively processed to give rise to functional mRNAs, rRNAs and tRNAs; starting with the release of tRNA elements through 5'-processing by RNase P (MRPP1/2/3-complex) and 3'-processing by RNase Z (ELAC2). Here, we show using in vitro experiments that MRPP1/2 is not only a component of the mitochondrial RNase P but that it retains the tRNA product from the 5'-processing step and significantly enhances the efficiency of ELAC2-catalyzed 3'-processing for 17 of the 22 tRNAs encoded in the human mitochondrial genome. Furthermore, MRPP1/2 retains the tRNA product after ELAC2 processing and presents the nascent tRNA to the mitochondrial CCA-adding enzyme. Thus, in addition to being an essential component of the RNase P reaction, MRPP1/2 serves as a processing platform for several down-stream tRNA maturation steps in human mitochondria. These findings are of fundamental importance for our molecular understanding of disease-related mutations in MRPP1/2, ELAC2 and mitochondrial tRNA genes.

MeSH terms

  • 3-Hydroxyacyl CoA Dehydrogenases / metabolism*
  • Humans
  • Methyltransferases / metabolism*
  • Mitochondria / enzymology
  • Mitochondria / genetics*
  • Neoplasm Proteins / metabolism
  • RNA Processing, Post-Transcriptional*
  • RNA, Transfer / metabolism*
  • Ribonuclease P / metabolism*


  • ELAC2 protein, human
  • Neoplasm Proteins
  • RNA, Transfer
  • 3-Hydroxyacyl CoA Dehydrogenases
  • HSD17B10 protein, human
  • Methyltransferases
  • TRMT10c protein, human
  • Ribonuclease P