The human mitochondrial translation release factor HMRF1L is methylated in the GGQ motif by the methyltransferase HMPrmC.
We have recently identified the human mitochondrial release factor, HMRF1L, which is responsible for decoding of UAA/UAG termination codons. Here, we identified human mitochondrial methyltransferase, HMPrmC, which methylates the glutamine residue in the GGQ tripeptide motif of HMRF1L. We demonstrate that HMPrmC is targeted to mitochondria and the glutamine residue in the GGQ motif of HMRF1L is methylated in vivo. HMPrmC depletion in HeLa cells leads to decreased mitochondrial translation activity in the presence of the translation fidelity antibiotic streptomycin in galactose containing medium. These results suggest that the methylation of HMRF1L by HMPrmC in human mitochondria is involved in the control of the translation termination process, probably by preventing the undesired suppression of termination codons and/or abortive termination events at sense codons under such conditions, as observed in prokaryotes and eukaryotes systems.
Ishizawa
Toshihiro
T
Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Building FSB-401, 5-1-5, Kashiwanoha, Kashiwa, Chiba Prefecture 277-8562, Japan.
Nozaki
Yusuke
Y
Ueda
Takuya
T
Takeuchi
Nono
N
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D018388:Codon, Terminator / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational; D010454:Peptide Termination Factors / Q000378:metabolism*; D034622:RNA Interference
D018388:Codon, Terminator; C523958:MTRF1L protein, human; D024101:Mitochondrial Proteins; D010454:Peptide Termination Factors; D005973:Glutamine; C530390:HMPrmC protein, human; D008780:Methyltransferases