Genetic screens in Saccharomyces cerevisiae identify a role for 40S ribosome recycling factors Tma20/22 in nonsense mediated decay.

The decay of messenger RNA with a premature termination codon (PTC) by nonsense mediated decay (NMD) is an important regulatory pathway for eukaryotes and an essential pathway in mammals. NMD is typically triggered by the ribosome terminating at a stop codon that is aberrantly distant from the poly-A tail. Here, we use a fluorescence screen to identify factors involved in NMD in S. cerevisiae. In addition to the known NMD factors, including the entire UPF family (UPF1, UPF2 and UPF3), as well as NMD4 and EBS1, we identify factors known to function in post-termination recycling and characterize their contribution to NMD. These observations in Saccharomyces cerevisiae expand on data in mammals indicating that the 60S recycling factor ABCE1 is important for NMD (Zhu et al. 2020; Annibaldis et al. 2020) by showing that perturbations in factors implicated in 40S recycling also correlate with a loss of NMD.