Ded1

Ded1 is a DEAD-box RNA helicase in the budding yeast Saccharomyces cerevisiae, encoded by the DED1 gene. It belongs to the DEAD-box family of enzymes, named for the conserved Asp-Glu-Ala-Asp motif in its catalytic core. Ded1 uses ATP hydrolysis to unwind RNA duplexes and remodel RNA–protein complexes, enabling various RNA metabolic processes.

In translation initiation, Ded1 plays a central role by promoting the scanning of the 5' untranslated region and aiding efficient ribosome recruitment to mRNAs. It acts in concert with the eIF4F complex, including eIF4E and eIF4G, and the helicase eIF4A, to resolve structured 5' UTRs and facilitate start codon recognition. Beyond initiation, Ded1 participates in broader RNA metabolism, influencing mRNA stability and turnover as part of interconnected RNA processing networks.

Cellular localization and regulation are context-dependent. Ded1 is predominantly cytoplasmic but can shuttle between compartments. Under stress conditions such as heat shock or nutrient limitation, Ded1 relocalizes to stress granules, where it co-localizes with poly(A) binding protein Pab1 and other granule components. This relocalization is associated with translational repression and selective mRNA storage during stress. Ded1’s helicase activity is modulated by interactions with initiation factors and by post-translational modifications, enabling rapid responses to cellular conditions.

Evolutionary context and significance. Yeast Ded1 has functional and structural parallels with the human DDX3 family of RNA helicases, sharing conserved catalytic motifs and core architecture. As a conserved regulator of translation and RNA metabolism, Ded1 exemplifies the central role of DEAD-box helicases in controlling gene expression at the level of mRNA structure and initiation.