Division of Labor in an Oligomer of the DEAD-Box RNA Helicase Ded1p

• DOI: 10.1016/j.molcel.2015.06.030
• Publication Date: 2015-07-23T15:45:52Z
• Authors: Andrea A. Putnam; Zhaofeng Gao; Fei Liu; Huijue Jia; Quansheng Yang; Eckhard Jankowsky
• Keywords: 0303 health sciences; Saccharomyces cerevisiae Proteins; Hydrolysis; Cell Biology; Saccharomyces cerevisiae; DEAD-box RNA Helicases; Protein Subunits; 03 medical and health sciences; Adenosine Triphosphate; Biocatalysis; Protein Multimerization; Protein Structure, Quaternary; Molecular Biology; Protein Binding; RNA, Double-Stranded

Most aspects of RNA metabolism involve DEAD-box RNA helicases, enzymes that bind and remodel RNA and RNA-protein complexes in an ATP-dependent manner. Here we show that the DEAD-box helicase Ded1p oligomerizes in the cell and in vitro, and unwinds RNA as a trimer. Two protomers bind the single-stranded region of RNA substrates and load a third protomer to the duplex, which then separates the strands. ATP utilization differs between the strand-separating protomer and those bound to the single-stranded region. Binding of the eukaryotic initiation factor 4G to Ded1p interferes with oligomerization and thereby modulates unwinding activity and RNA affinity of the helicase. Our data reveal a strict division of labor between the Ded1p protomers in the oligomer. This mode of oligomerization fundamentally differs from other helicases. Oligomerization represents a previously unappreciated level of regulation for DEAD-box helicase activities.