Poster abstracts
Poster number 133 submitted by Lucas Serdar
ATP hydrolysis by UPF1 promotes translation termination at premature stop codons
Lucas D. Serdar (Center for RNA Molecular Biology, Case Western Reserve University), DaJuan L. Whiteside (Center for RNA Molecular Biology, Case Western Reserve University), Kristian E. Baker (Center for RNA Molecular Biology, Case Western Reserve University)
Abstract:
Premature termination of translation at nonsense codons present within mRNA protein coding regions yields C-terminally truncated polypeptides with potentially deleterious functions to the cell. Nonsense-mediated mRNA decay (NMD) represents a quality control pathway that limits production of these aberrant protein products by recognizing the nonsense-containing mRNA and targeting it to accelerated degradation. How the NMD machinery is able to monitor the relative position of the terminating ribosome to determine it is premature, and communicate this information to the mRNA decay machinery remains unclear. The ATPase activity of the RNA helicase UPF1 is essential for NMD, however, the precise role and site of action of ATP hydrolysis by UPF1 during NMD remain unresolved. We show here that in yeast, expression of ATPase-deficient UPF1 results in the accumulation of 3’ mRNA decay fragments harboring ribosomes stalled in the vicinity of the premature termination codon. Moreover, we demonstrate that the ability of UPF1 to impinge upon premature termination requires its RNA binding activity, as well as its ability to associate with NMD co-factors UPF2 and UPF3. Our results reveal a functional interaction between UPF1 and the terminating ribosome that is dependent upon UPF1 ATPase activity and necessary for efficient targeting of NMD substrates to rapid degradation. These data give rise to a refined model of NMD substrate recognition and add to growing evidence that mRNA stability is tightly controlled by events directly impacting mRNA translation.
Keywords: NMD, mRNA Decay, Translation