Mtt1 is a Upf1-like helicase that interacts with the translation termination factors and whose overexpression can modulate termination efficiency
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.(Received November 11 1999)
(Revised December 27 1999)
(Accepted March 9 2000)
Key Words: helicase; nonsense-mediated mRNA decay; release factor; RNA; translation termination.
c1 Reprint requests to: Stuart W. Peltz, Department of Molecular Genetics and Microbiology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA; e-mail: Peltz@rwja.umdnj.edu.
p1 Present address: European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117, Heidelberg, Germany.