Table of Contents
Advances in Biology
Volume 2016, Article ID 1840782, 6 pages
http://dx.doi.org/10.1155/2016/1840782
Research Article

Amino Acid Starvation Enhances Programmed Ribosomal Frameshift in Metavirus Ty3 of Saccharomyces cerevisiae

Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey

Received 16 April 2016; Accepted 14 June 2016

Academic Editor: Yoshito Abe

Copyright © 2016 Sezai Türkel. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ty3 is a retroviral-like element and propagates with a retroviral-like mechanism within the yeast cells. Ty3 mRNA contains two coding regions, which are GAG3 and POL3. The coding region POL3 is translated as a GAG3-POL3 fusion protein by a +1 programmed frameshift. In this study, it was shown that the Ty3 frameshift frequency is significantly increased by amino acid starvation in a Gcn2p complex dependent manner. When the yeast cells were subjected to amino acid starvation, the frameshift frequency of Ty3 increased more than 2-fold in the wild-type yeast cells, mostly independent of Gcn4p. However, Ty3 frameshift frequency remained at basal level in the gcn1, gcn20, or gcn2 mutant yeast cells in amino acid starved yeasts. Gcn1p forms a complex with Gcn2p and Gcn20p and is involved in the sensing of uncharged tRNAs on the ribosomal A-site during translation. Increases in uncharged tRNA levels due to amino acid depletion lead to ribosomal pauses. These ribosomal pauses are significant actors in the regulation of Ty3 frameshift frequency. Results of this research revealed that frameshift frequency in Ty3 is regulated by the Gcn2p complex in response to amino acid starvation in yeast.