The DEAD-Box Protein Dhh1 Promotes Decapping by Slowing Ribosome Movement

Abstract

Author SummaryTranslation of mRNA into protein and turnover of mRNA are two points at which cells can exert regulatory control of gene expression, thereby ensuring that the protein products are present in cells and tissues at the appropriate time and place. The DDX6 family of DEAD box helicases, exemplified by the yeast protein Dhh1, is a group of well-conserved eukaryotic proteins that regulate translation and mRNA decay. As DDX6 proteins are known to be important for diverse processes such as cellular stress responses, early embryonic development, and replication of some viruses, understanding their mechanism of action could be of broad significance to many fields. Previous studies suggest that Dhh1 and other DDX6-family proteins mainly regulate translation at the initiation stage, triggering sequestration and/or decapping of the mRNA. Our work expands the potential functions of Dhh1, showing that Dhh1 is also capable of inhibiting translation at later stages when ribosomes are already loaded onto mRNAs. This extended function for Dhh1 allows a more robust translational control, as inhibition at a late stage of translation can provide immediate stoppage of protein production, as well as affording the potential for storing mRNA already primed and loaded with ribosomes for subsequent rapid re-utilization.