Loss of Ubp3 increases silencing, decreases unequal recombination in rDNA, and shortens the replicative life span in Saccharomyces cerevisiae.
Ubp3 is a conserved ubiquitin protease that acts as an antisilencing factor in MAT and telomeric regions. Here we show that ubp3∆ mutants also display increased silencing in ribosomal DNA (rDNA). Consistent with this, RNA polymerase II occupancy is lower in cells lacking Ubp3 than in wild-type cells in all heterochromatic regions. Moreover, in a ubp3∆ mutant, unequal recombination in rDNA is highly suppressed. We present genetic evidence that this effect on rDNA recombination, but not silencing, is entirely dependent on the silencing factor Sir2. Further, ubp3∆ sir2∆ mutants age prematurely at the same rate as sir2∆ mutants. Thus our data suggest that recombination negatively influences replicative life span more so than silencing. However, in ubp3∆ mutants, recombination is not a prerequisite for aging, since cells lacking Ubp3 have a shorter life span than isogenic wild-type cells. We discuss the data in view of different models on how silencing and unequal recombination affect replicative life span and the role of Ubp3 in these processes.
Department of Chemistry and Molecular Biology, University of Gothenburg, 413 90 Gothenburg, Sweden.
David
D
Oling
Department of Chemistry and Molecular Biology, University of Gothenburg, 413 90 Gothenburg, Sweden.
Rehan
R
Masoom
Department of Chemistry and Molecular Biology, University of Gothenburg, 413 90 Gothenburg, Sweden kristian.kvint@cmb.gu.se.
Kristian
K
Kvint
D018797:Cell Cycle Proteins / Q000378:metabolism; D015825:Chromosomes, Fungal / Q000235:genetics; D003434:Crossing Over, Genetic; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D055786:Gene Knockout Techniques; D020868:Gene Silencing; D006570:Heterochromatin / Q000201:enzymology / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D021381:Protein Transport; D012319:RNA Polymerase II / Q000378:metabolism; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000378:metabolism; D056565:Sirtuin 2 / Q000378:metabolism
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; C105579:FOB1 protein, S cerevisiae; D006570:Heterochromatin; C119300:Net1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D012319:RNA Polymerase II; D010450:Endopeptidases; C101111:UBP3 protein, S cerevisiae; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2