The DEAD-Box RNA Helicase Dbp5 Functions in Translation Termination

In eukaryotes, termination of messenger RNA (mRNA) translation is mediated by the release factors eRF1 and eRF3. Using Saccharomyces cerevisiae as a model organism, we have identified a member of the DEAD-box protein (DBP) family, the DEAD-box RNA helicase and mRNA export factor Dbp5, as a player in translation termination. Dbp5 interacts genetically with both release factors and the polyadenlyate-binding protein Pab1. A physical interaction was specifically detected with eRF1. Moreover, we show that the helicase activity of Dbp5 is required for efficient stop-codon recognition, and intact Dbp5 is essential for recruitment of eRF3 into termination complexes. Therefore, Dbp5 controls the eRF3-eRF1 interaction and thus eRF3-mediated downstream events.