Involvement of human ELAC2 gene product in 3' end processing of mitochondrial tRNAs

RNA Biol. Jul-Aug 2011;8(4):616-26. doi: 10.4161/rna.8.4.15393. Epub 2011 Jul 1.

Abstract

Accurate tRNA processing is crucial for human mitochondrial genome expression, but the mechanisms of mt-tRNA cleavage and the key enzymes involved in this process are poorly characterized. At least two activities are required for proper mt-tRNA maturation: RNase P cleaving precursor molecules at the 5' end and tRNase Z at the 3' end. In human mitochondria only RNase P has been identified so far. Using RT-PCR and northern blot analyses we found that silencing of the human ELAC2 gene results in impaired 3' end of mt-tRNAs. We demonstrate this for several mitochondrial tRNAs, encoded on both mtDNA strands, including tRNA (Val) , tRNA (Lys) , tRNA (Arg) , tRNA (Gly) , tRNA (Leu(UUR)) and tRNA (Glu) . The silencing of the MRPP1 gene that encodes a subunit of mtRNase P resulted in inhibition of both 5' and 3' processing. We also demonstrate the double mitochondrial/nuclear localization of the ELAC2 protein using immunofluorescence. Our results indicate that ELAC2 functions as a tRNase Z in human mitochondria and suggest that mt-tRNase Z preferentially cleaves molecules already processed by the proteinaceous mtRNase P.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cell Nucleus / enzymology
  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism
  • Endoribonucleases / metabolism
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Mitochondria / enzymology
  • Mitochondria / genetics*
  • Mitochondria / metabolism
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism*
  • RNA / genetics
  • RNA / metabolism*
  • RNA 3' End Processing / genetics*
  • RNA Interference
  • RNA, Mitochondrial
  • RNA, Small Interfering
  • RNA, Transfer / genetics*
  • RNA, Transfer / metabolism
  • Ribonuclease P / metabolism

Substances

  • ELAC2 protein, human
  • Neoplasm Proteins
  • RNA, Mitochondrial
  • RNA, Small Interfering
  • RNA
  • RNA, Transfer
  • Endoribonucleases
  • tRNase Z, human
  • Ribonuclease P