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PMID:15828860

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Citation

Vanácová, S, Wolf, J, Martin, G, Blank, D, Dettwiler, S, Friedlein, A, Langen, H, Keith, G and Keller, W (2005) A new yeast poly(A) polymerase complex involved in RNA quality control. PLoS Biol. 3:e189

Abstract

Eukaryotic cells contain several unconventional poly(A) polymerases in addition to the canonical enzymes responsible for the synthesis of poly(A) tails of nuclear messenger RNA precursors. The yeast protein Trf4p has been implicated in a quality control pathway that leads to the polyadenylation and subsequent exosome-mediated degradation of hypomethylated initiator tRNAMet (tRNAiMet). Here we show that Trf4p is the catalytic subunit of a new poly(A) polymerase complex that contains Air1p or Air2p as potential RNA-binding subunits, as well as the putative RNA helicase Mtr4p. Comparison of native tRNAiMet with its in vitro transcribed unmodified counterpart revealed that the unmodified RNA was preferentially polyadenylated by affinity-purified Trf4 complex from yeast, as well as by complexes reconstituted from recombinant components. These results and additional experiments with other tRNA substrates suggested that the Trf4 complex can discriminate between native tRNAs and molecules that are incorrectly folded. Moreover, the polyadenylation activity of the Trf4 complex stimulated the degradation of unmodified tRNAiMet by nuclear exosome fractions in vitro. Degradation was most efficient when coupled to the polyadenylation activity of the Trf4 complex, indicating that the poly(A) tails serve as signals for the recruitment of the exosome. This polyadenylation-mediated RNA surveillance resembles the role of polyadenylation in bacterial RNA turnover.

Links

PubMed PMC1079787 Online version:10.1371/journal.pbio.0030189

Keywords

DNA, Fungal/genetics; DNA-Directed DNA Polymerase/genetics; Molecular Sequence Data; Open Reading Frames; Plasmids; Polymerase Chain Reaction; Polynucleotide Adenylyltransferase/genetics; Polynucleotide Adenylyltransferase/metabolism; RNA, Fungal/genetics; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/growth & development; Saccharomyces cerevisiae Proteins/genetics; Saccharomyces cerevisiae Proteins/metabolism

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


See also

References

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