CCA-adding enzymes synthesize and maintain the C-C-A sequence at the tRNA 3'-end, generating the attachment site for amino acids. While tRNAs are the most prominent substrates for this polymerase, CCA
additions on non-tRNA transcripts are described as well. To identify general features for substrate requirement, a pool of randomized transcripts was incubated with the human CCA-adding enzyme. Most
of the RNAs accepted for CCA addition carry an acceptor stem-like terminal structure, consistent with tRNA as the main substrate group for this enzyme. While these RNAs show no sequence conservation,
the position upstream of the CCA end was in most cases represented by an adenosine residue. In tRNA, this position is described as discriminator base, an important identity element for correct aminoacylation. Mutational analysis of the impact of the discriminator
identity on CCA addition revealed that purine bases (with a preference for adenosine) are strongly favoured over pyrimidines. Furthermore, depending on the tRNA context, a cytosine discriminator can
cause a dramatic number of misincorporations during CCA addition. The data correlate with a high frequency of adenosine residues at the discriminator position observed in vivo. Originally identified as a
prominent identity element for aminoacylation, this position represents a likewise important element for efficient and accurate CCA addition.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:15-qucosa-172120 |
| Date | 09 May 2015 |
| Creators | Wende, Sandra, Bonin, Sonja, Götze, Oskar, Betat, Heike, Mörl, Mario |
| Contributors | Universität Leipzig, Institut für Biochemie, Oxford Univ. Press, |
| Publisher | Universitätsbibliothek Leipzig |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:article |
| Format | application/pdf |
| Source | Nucleic acids research 2015, 43 (11) |
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