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

Abstract

AbstractUnearthing of novel genetic interaction which leads to synthetic growth defects due to inactivation of genes are needed for applications in precision medicine. The genetic interactions among the molecular players involving different biological pathways need to be investigated. The SAF1 gene of S.cerevisiae encodes for a protein product which contain N-terminal F-box motif and C-terminal RCC1 domain. The F-box motif interacts with Skp1subunit of the SCF-E3 ligase and C-terminus with Aah1 (adenine deaminase) for ubiquitination and subsequent degradation by 26S proteasome during phase transition from proliferation state to quiescence phase due to nutrient limitation stress. The replication fork associated protein Rrm3 of S.cerevisiae belongs to Pif1 family helicase and function in removal of the non-histone proteins during replication fork movement. Here we have investigated the genetic interaction among both the genes (SAF1 and RRM3) and their role in growth fitness and genome stability. The single and double gene knockout strains of SAF1and RRM3 genes was constructed in BY4741 genetic background and checked for the growth fitness in presence of genotoxic stress causing agents such as hydroxyurea and methyl methanesulfonate. The strains were also evaluated for nuclear migration defect by DAPI staining and for HIS3AI marked Ty1 retro-transposition. The saf1Δrrm3Δ showed the extremely slow growth phenotype in rich medium and sensitivity to genotoxic agents such as HU and MMS in comparison to single gene mutant (saf1Δ, rrm3Δ) and WT cells. The saf1Δrrm3Δ also showed the defects in nuclear migration as evident by multi-nuclei phenotype. The saf1Δrrm3Δ also showed the elevated frequency of Ty1 retro-transposition in JC2326 background in comparison to either saf1Δ or rrm3Δ. Based on these observations we report that thatSAF1 and RRM3 functions in parallel pathway for growth fitness and stability of the genome.