Maya Villanueva, Aimee Lewis and Toby Thomas

Abstract:

Retrotransposons are mobile DNA elements present in genomes of many organisms and are expressed at higher levels with age. Previous studies have shown that cytosolic pH increases early during yeast aging, suggesting a potential connection between retrotransposition, aging, and cytosolic pH levels in yeast. Previous data from our lab demonstrates that overexpression of a plasma membrane proton pump, Pma1p, or a vacuolar pump positively contributes to yeast Ty1 retrotransposon mobility. To determine what step of Ty1 replication is affected by higher cytosolic pH, we combined Pma1p overexpression with mutants known to affect specific steps in Ty1 retromobility. We also further examined our previously reported finding that high copy numbers of Ty1 retrotransposons were correlated with lifespan extension of yeast cells exposed to a mild dose of hydroxyurea, a DNA replication stressor. Dozens of genes were differentially expressed in the presence of Ty1 and hydroxyurea, and we analyzed whether these changes are due to nearby Ty1 insertions.