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

• Published in: RNA biology Vol. 8; no. 4; pp. 616 - 626
• Main Authors: Brzezniak, Lien K., Bijata, Monika, Szczesny, Roman J., Stepien, Piotr P.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01-07-2011
• Subjects: Binding; Biology; Bioscience; Calcium; Cancer; Cell; Cell Line, Tumor; Cell Nucleus - enzymology; Cell Nucleus - genetics; Cell Nucleus - metabolism; Cycle; Endoribonucleases - metabolism; HEK293 Cells; HeLa Cells; Humans; Landes; Mitochondria - enzymology; Mitochondria - genetics; Mitochondria - metabolism; Neoplasm Proteins - genetics; Neoplasm Proteins - metabolism; Organogenesis; Proteins; Ribonuclease P - metabolism; RNA - genetics; RNA - metabolism; RNA 3' End Processing - genetics; RNA Interference; RNA, Small Interfering; RNA, Transfer - genetics; RNA, Transfer - metabolism
• ISSN: 1547-6286; 1555-8584
• DOI: 10.4161/rna.8.4.15393

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.