Research Paper Volume 10, Issue 3 pp 402—424

Preferential Ty1 retromobility in mother cells and nonquiescent stationary phase cells is associated with increased concentrations of total Gag or processed Gag and is inhibited by exposure to a high concentration of calcium

Andrew C. Peifer 1, , Patrick H. Maxwell 1, 2, ,

  • 1 Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
  • 2 Wadsworth Center, Division of Genetics, Albany, NY 12208, USA

received: November 22, 2017 ; accepted: March 16, 2018 ; published: March 21, 2018 ;

https://doi.org/10.18632/aging.101402
How to Cite

Copyright: Peifer and Maxwell. This is an open‐access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Retrotransposons are abundant mobile DNA elements in eukaryotic genomes that are more active with age in diverse species. Details of the regulation and consequences of retrotransposon activity during aging remain to be determined. Ty1 retromobility in Saccharomyces cerevisiae is more frequent in mother cells compared to daughter cells, and we found that Ty1 was more mobile in nonquiescent compared to quiescent subpopulations of stationary phase cells. This retromobility asymmetry was absent in mutant strains lacking BRP1 that have reduced expression of the essential Pma1p plasma membrane proton pump, lacking the mRNA decay gene LSM1, and in cells exposed to a high concentration of calcium. Mother cells had higher levels of Ty1 Gag protein than daughters. The proportion of protease-processed Gag decreased as cells transitioned to stationary phase, processed Gag was the dominant form in nonquiescent cells, but was virtually absent from quiescent cells. Treatment with calcium reduced total Gag levels and the proportion of processed Gag, particularly in mother cells. We also found that Ty1 reduced the fitness of proliferating but not stationary phase cells. These findings may be relevant to understanding regulation and consequences of retrotransposons during aging in other organisms, due to conserved impacts and regulation of retrotransposons.

Abbreviations

CFU: colony-forming-units; CLS: chronological lifespan; ER: endoplasmic reticulum; NQ: nonquiescent; ORF: open reading frame; Q: quiescent; SC: synthetic complete medium; WGA: wheat germ agglutinin; YPD: yeast extract-peptone-glucose medium; YPE: yeast extract-peptone-ethanol medium.