The Effect of Dia2 Protein Deficiency on the Cell Cycle, Cell Size, and Recruitment of Ctf4 Protein in Saccharomyces cerevisiae

Abstract

Cells have evolved elaborate mechanisms to regulate DNA replication machinery and cell cycles in response to DNA damage and replication stress in order to prevent genomic instability and cancer. The E3 ubiquitin ligase SCFDia2 in S. cerevisiae is involved in the DNA replication and DNA damage stress response, but its effect on cell growth is still unclear. Here, we demonstrate that the absence of Dia2 prolongs the cell cycle by extending both S- and G2/M-phases while, at the same time, activating the S-phase checkpoint. In these conditions, Ctf4—an essential DNA replication protein and substrate of Dia2—prolongs its binding to the chromatin during the extended S- and G2/M-phases. Notably, the prolonged cell cycle when Dia2 is absent is accompanied by a marked increase in cell size. We found that while both DNA replication inhibition and an absence of Dia2 exerts effects on cell cycle duration and cell size, Dia2 deficiency leads to a much more profound increase in cell size and a substantially lesser effect on cell cycle duration compared to DNA replication inhibition. Our results suggest that the increased cell size in dia2∆ involves a complex mechanism in which the prolonged cell cycle is one of the driving forces.

An epigenetically inherited UV hyper-resistance phenotype in Saccharomyces cerevisiae

“…It is conceivable that exposure to UV triggers changes in cell cycle progression after the resolution of DNA damage checkpoint activation, leading to enrichment of UV hyper-resistant G2 cells in the growing culture population. Furthermore, it has been shown that prolonging the cell cycle leads to an increase in yeast cell size [ 38 ], which may enhance the UVHR phenotype. The epigenetic nature of the UVHR phenotype suggests that the putative altered cell cycle distribution and associated cell size changes subsequently propagate over multiple cell generations to provide inheritable protection against recurrent UV exposure.…”