tRNAs marked with CCACCA are targeted for degradation.

Koch Institute for Integrative Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Science (Impact Factor: 31.48). 11/2011; 334(6057):817-21. DOI: 10.1126/science.1213671
Source: PubMed

ABSTRACT The CCA-adding enzyme [ATP(CTP):tRNA nucleotidyltransferase] adds CCA to the 3' ends of transfer RNAs (tRNAs), a critical step in tRNA biogenesis that generates the amino acid attachment site. We found that the CCA-adding enzyme plays a key role in tRNA quality control by selectively marking structurally unstable tRNAs and tRNA-like small RNAs for degradation. Instead of adding CCA to the 3' ends of these transcripts, CCA-adding enzymes from all three kingdoms of life add CCACCA. In addition, hypomodified mature tRNAs are subjected to CCACCA addition as part of a rapid tRNA decay pathway in vivo. We conjecture that CCACCA addition is a universal mechanism for controlling tRNA levels and preventing errors in translation.

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