Talk on Friday 02:30-02:45pm submitted by Zhaofeng Gao
Direct interaction and functional coupling of the DEAD-box RNA helicases, eIF4A and Ded1p, from Saccharomyces cerevisiae
Zhaofeng Gao (Center for RNA Molecular Biology and Department of Biochemistry, Case Western Reserve University, Cleveland, OH ), Andrea Putnam, Heath Bowers, Ulf-Peter Guenther, Xuan Ye (Center for RNA Molecular Biology and Department of Biochemistry, Case Western Reserve University, Cleveland, OH ), Angela Hilliker (Department of Biology, The University of Richmond, Richmond, Virginia), Eckhard Jankowsky (Center for RNA Molecular Biology and Department of Biochemistry, Case Western Reserve University, Cleveland, OH )
The eukaryotic translation initiation factor 4F (eIF4F) consists of the large scaffolding and RNA binding protein eIF4G, the cap-binding protein eIF4E, and the DEAD-box RNA helicase eIF4A. In Saccharomyces cerevisiae, another DEAD-box RNA helicase, Ded1p also interacts with eIF4G. Here, we show that the two DEAD-box helicases are physically and functionally coupled.
We find that eIF4A suppresses the cold-sensitive ded1 mutant alleles in vivo, and that eIF4A directly binds to Ded1p. Unwinding stimulations are observed between Ded1p and eIF4A, without or with the presence of eIF4G.
We further show that despite the presence of two RNA helicases in the Ded1p-eIF4G/4A complex, Ded1p is the unwinding module. eIF4A and eIF4G exert regulatory functions that depend on the concentrations of Ded1p, eIF4A, eIF4G and ATP. A basic thermodynamic model of the various complexes that form among Ded1p, eIF4G, eIF4A, RNA and ATP indicates that complexes containing eIF4A, eIF4G and Ded1p have the highest thermodynamic stabilities.
Collectively, our findings reveal intricate functional coupling between Ded1p, eIF4A and eIF4G, and demonstrate that eIF4A and Ded1p work simultaneously on eIF4G, and suggests that Ded1p is an integral part of the eIF4F complex.
Keywords: eIF4A, Ded1p, eIF4G