tRNA processing

Stable Identifier
R-HSA-72306
Type
Pathway
Species
Homo sapiens
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General
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Genes encoding transfer RNAs (tRNAs) are transcribed by RNA polymerase III in the nucleus and by mitochondrial RNA polymerase in the mitochondrion.
In the nucleus transcription reactions produce precursor tRNAs (pre-tRNAs) that have extra 5' leaders, 3' trailers, and, in some cases, introns which are removed by enzymes and enzyme complexes: RNase P cleaves the 5' leader, RNase Z cleaves the 3' trailer, TRNT1 polymerizes CCA onto the resulting 3' end, the TSEN complex cleaves at each end of the intron, and the tRNA ligase complex ligates the resulting exons (reviewed in Rossmanith et al. 1995, Phizicky and Hopper 2010, Suzuki et al. 2011, Abbott et al. 2014, Li and Mason 2014). The nucleotides within tRNAs undergo further chemical modifications such as methylation and deamination by a diverse set of enzymes (reviewed in Helm and Alfonzo 2014, Boschi-Muller and Motorin 2013). The order of events for each tRNA is not fully known and the understanding of the overall process is complicated by the retrograde (cytosol to nucleus) transport of tRNAs.
In the mitochondrial matrix transcription produces long precursor RNAs, H strand transcripts and an L strand transcript, that are cleaved by mitochondrial RNase P (an entirely proteinaceous complex), ELAC2, and other nucleases to yield 12S rRNA, 16S rRNA, mRNAs, and pre-tRNAs lacking 3' CCA sequences (reviewed in Van Haute et al. 2015). TRNT1 polymerizes an untemplated CCA sequence onto the 3' ends of the pre-tRNAs and chemical modifications are made to several nucleotides in the tRNAs.

Literature References
PubMed ID Title Journal Year
26016801 Mitochondrial transcript maturation and its disorders

Van Haute, L, Pearce, SF, Powell, CA, D'Souza, AR, Nicholls, TJ, Minczuk, M

J. Inherit. Metab. Dis. 2015
24490730 Chemistry enters nucleic acids biology: enzymatic mechanisms of RNA modification

Boschi-Muller, S, Motorin, Y

Biochemistry Mosc. 2013
21910628 Human mitochondrial tRNAs: biogenesis, function, structural aspects, and diseases

Suzuki, T, Nagao, A, Suzuki, T

Annu. Rev. Genet. 2011
24898039 The pivotal regulatory landscape of RNA modifications

Li, S, Mason, CE

Annu Rev Genomics Hum Genet 2014
7759547 Human mitochondrial tRNA processing

Rossmanith, W, Tullo, A, Potuschak, T, Karwan, R, Sbisà, E

J. Biol. Chem. 1995
20810645 tRNA biology charges to the front

Phizicky, EM, Hopper, AK

Genes Dev. 2010
24917879 Transfer RNA and human disease

Abbott, JA, Francklyn, CS, Robey-Bond, SM

Front Genet 2014
24315934 Posttranscriptional RNA Modifications: playing metabolic games in a cell's chemical Legoland

Helm, M, Alfonzo, JD

Chem. Biol. 2014
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