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キーワード:
Animals
Cardiomyopathies/metabolism/pathology
DNA, Mitochondrial/genetics
Electron Transport
Embryonic Development
Gene Expression Regulation, Developmental
Mammals/*metabolism
Methylation
Mice
Mice, Knockout
Mitochondria/genetics/*metabolism/ultrastructure
Myocardium/pathology/ultrastructure
Organ Specificity
Protein Biosynthesis
RNA, Messenger/genetics/metabolism
RNA, Ribosomal/*metabolism
Ribosome Subunits, Small, Eukaryotic/*metabolism
Transcription Factors/deficiency/genetics/metabolism
Transcription, Genetic
要旨:
The 3' end of the rRNA of the small ribosomal subunit contains two extremely highly conserved dimethylated adenines. This modification and the responsible methyltransferases are present in all three domains of life, but its function has remained elusive. We have disrupted the mouse Tfb1m gene encoding a mitochondrial protein homologous to bacterial dimethyltransferases and demonstrate here that loss of TFB1M is embryonic lethal. Disruption of Tfb1m in heart leads to complete loss of adenine dimethylation of the rRNA of the small mitochondrial ribosomal subunit, impaired assembly of the mitochondrial ribosome, and abolished mitochondrial translation. In addition, we present biochemical evidence that TFB1M does not activate or repress transcription in the presence of TFB2M. Our results thus show that TFB1M is a nonredundant dimethyltransferase in mammalian mitochondria. In addition, we provide a possible explanation for the universal conservation of adenine dimethylation of rRNA by showing a critical role in ribosome maintenance.
