Mtt1 is a Upf1-like helicase that interacts with the translation termination factors and whose overexpression can modulate termination efficiency

Abstract

Translation termination is the final step that completes the synthesis of a polypeptide. Premature translation termination by introduction of a nonsense mutation leads to the synthesis of a truncated protein. We report the identification and characterization of the product of the MTT1 gene, a helicase belonging to the Upf1-like family of helicases that is involved in modulating translation termination. MTT1 is homologous to UPF1, a factor previously shown to function in both mRNA turnover and translation termination. Overexpression of MTT1 induced a nonsense suppression phenotype in a wild-type yeast strain. Nonsense suppression is apparently not due to induction of [PSI + ], even though cooverexpression of HSP104 alleviated the nonsense suppression phenotype observed in cells overexpressing MTT1, suggesting a more direct role of Hsp104p in the translation termination process. The MTT1 gene product was shown to interact with translation termination factors and is localized to polysomes. Taken together, these results indicate that at least two members of a family of RNA helicases modulate translation termination efficiency in cells.

Poly(A)-Binding Protein Acts in Translation Termination via Eukaryotic Release Factor 3 Interaction and Does Not Influence [PSI+] Propagation

“…Although genetic data suggest a functional relationship between eRF3 and Hsp104 (14), a physical interaction between these proteins could not be demonstrated (84). Upf1-like helicase Mtt1 also interacts with eRF3, but the domain of interaction within eRF3 was not precisely localized; two interaction domains were described previously (20).…”

“…Upf2p and Upf3p have been shown previously to interact only with the release factor eRF3 (99). Recently another protein, the product of the MTT1 gene, modulating the efficiency of translation termination and interacting with eRF3, was described (20). Also it has been shown previously that the Sla1 protein, involved in the assembly of cortical actin cytoskeleton, interacts with the prion-forming domain of eRF3 in yeast (4).…”

Omnipotent decoding potential resides in eukaryotic translation termination factor eRF1 of variant-code organisms and is modulated by the interactions of amino acid sequences within domain 1

“…In contrast, in an in vivo system, uncountable numbers of other essential components are present. First of all, the class-II termination factor, eRF3, Upf proteins known to interact with termination factors in vivo and in vitro (33), natural mRNA (it is well known that termination in vivo strongly depends on the context of stop codons; ref. 34), numerous tRNAs that compete with eRF1 for the A site binding.…”

Eukaryotic release factors (eRFs) history

“…Among these are the Upf1-like helicase Mtt1 (Czaplinski et al, 2000) and Itt1 protein (Urakov et al, 2001). Both proteins interact with eRF1 and eRF3.…”