Dom34:hbs1 plays a general role in quality-control systems by dissociation of a stalled ribosome at the 3' end of aberrant mRNA.

ABSTRACT

Translation arrest leads to an endonucleolytic cleavage of mRNA that is termed no-go decay (NGD). It has been reported that the Dom34Hbs1 complex stimulates this endonucleolytic cleavage of mRNA induced by translation arrest in vivo and dissociates subunits of a stalled ribosome in vitro. Here we report that Dom34Hbs1 dissociates the subunits of a ribosome that is stalled at the 3' end of mRNA in vivo, and has a crucial role in both NGD and nonstop decay. Dom34Hbs1-mediated dissociation of a ribosome that is stalled at the 3' end of mRNA is required for degradation of a 5'-NGD intermediate. Dom34Hbs1 facilitates the decay of nonstop mRNAs from the 3' end by exosomes and is required for the complete degradation of nonstop mRNA decay intermediates. We propose that Dom34Hbs1 stimulates degradation of the 5'-NGD intermediate and of nonstop mRNA by dissociating the ribosome that is stalled at the 3' end of the mRNA.