Loss of F-box Motif Encoding Gene SAF1 and RRM3 Together Leads to Synthetic Growth Defect and Sensitivity to HU, MMS inS.cerevisiae

Abstract

The analysis of the nucleus using DAPI stain indicated increased percentage of cells showing 126 multi-nuclei phenotype in saf1∆rrm3∆ cellsin comparison to saf1∆, rrm3∆, and WT ( Figure 127 2A). The multi-nuclei phenotype indicated the defect in the nuclear migration.. 128The saf1∆rrm3∆cells showed increased Ty1 retro-transposition 129 Ty1 elements are class of retro-transposons in the S. cerevisiae genome which remain in the 130 dormant state due the host encoded genetic factors. In the absence of RRM3, the frequency 131 of Ty1retro-transposition goes up as reported previously (15, 16). In this study the single 132 gene mutant saf1∆showed nearly 8 fold whereas the rrm3∆ showed the 85fold change in 133 His+ prototroph formation in comparison to WT. However the absence of both the genes 134 (saf1∆rrm3∆) leads to increased frequency (~ 180-fold) of Ty1-retro transposition in the 135 comparison to WT cells. (Figure 3 A, B). 136 Loss of SAF1 and RRM3 leads to HU and MMS sensitivity 137 The hydroxyurea (HU) and methyl methanesulfonate (MMS) act as replication checkpoint 138 inhibitor and DNA damaging agent respectively. The Rrm3 mutant reported to have slightly 139 sensitive phenotype in the 200mM hydroxyurea (22). With regard to SAF1 mutant the data is 140 not available. The semi-quantitative growth assay by spot analysis on YPD medium and 180 Manjithya, NCBS, India for strains and plasmids.