RNase PH hexamer, Pseudomonas aeruginosa
|PDB structures||RCSB PDB PDBe PDBsum|
|Gene Ontology||AmiGO / QuickGO|
- tRNAn+1 + phosphate tRNAn + a nucleoside diphosphate
where tRNA-N is a product of transcription, and tRNA Nucleotidyltransferase catalyzes this cytidine-cytidine-adenosine (CCA) addition to form the tRNA-NCCA product.
Protein synthesis takes place in cytosolic ribosomes, mitochondria (mitoribosomes), and in plants, the plastids (chloroplast ribosomes). Each of these compartments requires a complete set of functional tRNAs to carry out protein synthesis. The production of mature tRNAs requires processing and modification steps such as the addition of a 3’-terminal cytidine-cytidine-adenosine (CCA). Since no plant tRNA genes encode this particular sequence, a tRNA nucleotidyltransferase must add this sequence post-transcriptionally and therefore is present in all three compartments.
In eukaryotes, multiple forms of tRNA nucleotidyltransferases are synthesized from a single gene and are distributed to different subcellular compartments in the cell. There are multiple in-frame start codons which allow for the production of variant forms of the enzyme containing different targeting information predominantly found in the N-terminal sequence of the protein (reference). In vivo experiments show that the N-terminal sequences are used as transit peptides for import into the mitochondria and plastids. Comparison studies using available tRNA nucleotidyltransferase sequences have identified a single gene coding for this enzyme in plants. Complementation studies in yeast using cDNA derived from Arabidopsis thaliana or Lupinus albus genes demonstrate the biological activity of these enzymes. The enzyme has also been shown to repair damaged or incomplete CCA sequences in yeast.
- Hopper AK, Phizicky EM (January 2003). "tRNA transfers to the limelight". Genes Dev. 17 (2): 162–80. doi:10.1101/gad.1049103. PMID 12533506.
- Gu J (2000). Identification of proteins interacting with lupin and Arabidopsis tRNA nucleotidyltransferase (MSc). Concordia University, Canada. pp. 51–55.
- Shanmugam K, Hanic-Joyce PJ, Joyce PB (January 1996). "Purification and characterization of a tRNA nucleotidyltransferase from Lupinus albus and functional complementation of a yeast mutation by corresponding cDNA". Plant Mol. Biol. 30 (2): 281–95. doi:10.1007/bf00020114. PMID 8616252.
- Rosset R, Monier R (November 1965). "[Instability of the terminal 3'-hydroxy sequence of transfer RNA in microorganisms. I. Turnover of terminal AMP in Saccharomyces cerevisiae]". Biochim. Biophys. Acta (in French). 108 (3): 376–84. doi:10.1016/0005-2787(65)90030-4. PMID 4286478.
- Cudny H, Deutscher MP (1988). "3' processing of tRNA precursors in ribonuclease-deficient Escherichia coli. Development and characterization of an in vitro processing system and evidence for a phosphate requirement". J. Biol. Chem. 263 (3): 1518–23. PMID 3275667.
- Deutscher MP, Marshall GT, Cudny H (1988). "RNase PH: an Escherichia coli phosphate-dependent nuclease distinct from polynucleotide phosphorylase". Proc. Natl. Acad. Sci. U.S.A. 85 (13): 4710–14. doi:10.1073/pnas.85.13.4710. PMC 280505. PMID 2455297.
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