Investigation of the effects of nitrogen signaling on the gene expression in Ty viruses

Ty elements are present in 5 different types in Sacchoromyces cerevisiae genome. They transpose within the yeast genome through an RNA intermediate and also named as retrotransposons. Their copy number in the yeast genome is constant. Since the propagation mechanisms of Ty1 and Ty2 in the yeast genomes resemble to retroviruses, they are also called as pseudoviruses. Gene expression in Ty elements is controlled at transcription translation level. Ty elements do not encode any regulatory factors for their transcriptional and translational regulation from their genome. Hence their replication cycles completely depend on the yeast encoded factors. Therefore it is expected that any metabolic or physiological signal that affects the gene expression in S. cerevisiae, also affects the transcription and translation process in Ty elements. Nitrogen is one of the basic elements required for cellular metabolic events. Nitrogen sensing and signaling is under the genetic control in yeast. The types and the quantities of nitrogen sources directly affect the growth rate and the expression levels of many genes in S. cerevisiae. In this thesis research, the effects of nitrogen source and nitrogen signaling on the gene expression in Ty1 and Ty2 were investigated. Results of this study indicated that TOR kinase and the GATA factors that are major regulators of nitrogen signaling in yeast, might control the gene expression in Ty1 and Ty2 element of S. cerevisiae.