REVIEW COMMUNICATIONS GENETICS GENETICS From past to future: suppressor mutations in yeast genes encoding translation termination factors Nina Trubitsina 1 , Olga Zemlyanko 1,2 , Svetlana Moskalenko 1,3 , and Galina Zhouravleva 1,4 1 Department of Genetics and Biotechnology, Faculty of Biology, Saint Petersburg State University, Universitetskaya nab., 7–9, Saint Petersburg, 199034, Russian Federation 2 St. Petersburg Scientifc Center, Russian Academy of Sciences, Universitetskaya nab., 5, Saint Petersburg, 199034, Russian Federation 3 Vavilov Institute of General Genetics Russian Academy of Sciences, Saint Petersburg Branch, Universitetskaya nab., 7–9, Saint Petersburg, 199034, Russian Federation 4 Laboratory of Amyloid Biology, Saint Petersburg State University, Botanicheskaya Str., 17a, Peterhof, 198504, Russian Federation Address correspondence and requests for materials to Galina Zhouravleva, g.zhuravleva@spbu.ru Abstract The study of the SUP45 and SUP35 genes of yeast Saccharomyces cerevisiae in the laboratory of Physiological Genetics of St. Petersburg State University be- gan in 1964 when the frst omnipotent nonsense suppressor mutations were obtained. During the following 55 years, a lot of information about these genes has been gained through the research eforts of various laboratories. Now we know that SUP45 and SUP35 encode translation termination factors eRF1 and eRF3, respectively. Both genes are essential, and sup45 and sup35 mutations lead not only to impaired translation but also to multiple pleiotropic efects. The aim of this review is to summarize known data about suppressor mutations in SUP45 or SUP35 genes. Keywords: translation termination, suppression, SUP45, SUP35, eRF1, eRF3, nonsense mutations, missense mutations, [PSI + ] prion, S. cerevisiae. Introduction In eukaryotes, translation termination requires two eukaryotic release factors: eRF1 and eRF3. Te eRF1 protein belongs to class 1 translation termination fac- tors, responsible for the recognition of the stop codon and peptidyl-tRNA hydro- lysis, and eRF3 — to class 2 termination factors, functioning to stimulate the work of class 1 factors due to its GTPase activity. Most eukaryotic organisms have a single class 1 translation termination factor called eRF1 (Frolova et al., 1994) that recognizes all three stop codons. In eukaryotic cells, class 2 translation termina- tion factors are represented by eRF3 proteins (Stansfeld et al., 1995a; Zhourav- leva et al., 1995). Although all living organisms have a similar general transla- tion termination mechanism, there are signifcant diferences primarily between prokaryotes and eukaryotes (see review by Kisselev et al., 2003). During the last years several additional proteins participating in eukaryotic translation termina- tion have been identifed, including ABCE1 (Rli1 in S. cerevisiae), Dbp5, PABP, Hrp1, Pub1 and Upf proteins (see reviews by Tieg and Krebber, 2013; Schuller and Green, 2018). It should be noted that the role of translation termination factors in the cell seems not to be limited to participation in translation termination, and these pro- teins are also likely to be involved in other stages of translation and diferent cel- lular processes. Citation: Trubitsina, N., Zemlyanko, J., Moskalenko, S., and Zhouravleva, G. 2019. From past to future: suppressor mutations in yeast genes encoding translation termination factors. Bio. Comm. 64(2): 89–109. https://doi.org/10.21638/ spbu03.2019.202 Author’s information: Nina Trubitsina, PhD student, orcid.org/0000-0002-8892- 8043; Olga Zemlyanko, Junior Researcher, orcid.org/0000-0003-3463-6675; Svetlana Moskalenko, PhD, Senior Researcher, orcid.org/0000-0003-0419-0000; Galina Zhouravleva, Dr. of Sci. in Biology, Professor, Head of Department, orcid.org/0000-0002- 3013-4662 Manuscript Editor: Alla Krasikova, Department of Cytology and Histology, Faculty of Biology, Saint Petersburg State University, Saint Petersburg, Russia Received: May 6, 2019; Revised: June 17, 2019; Accepted: June 20, 2019; Copyright: © 2019 Trubitsina et al. This is an open-access article distributed under the terms of the License Agreement with Saint Petersburg State University, which permits to the authors unrestricted distribution, and self-archiving free of charge. Funding: This work was supported by grants from the Russian Science Foundation (Grant 18-14-00050) (parts 1-5) and the Russian Foundation for Basic Research (Grant 19-04-00173) (part 6: “Suppression due to prion [PSI+]”); modelling of the 3D structure of eRF1-eRF3C-GDPNP protein complex with suppressor missense mutations was done in the frame of the State Research Program (0112-2016-0015). Competing interests: The authors have declared that no competing interests exist.