NHEJ regulation by mating type is exercised through a novel protein, Lif2p, essential to the ligase IV pathway.
In the yeast Saccharomyces cerevisiae, DNA double strand break (DSB) repair by nonhomologous end-joining (NHEJ) requires the DNA end-binding heterodimer Yku70p-Yku80p and the ligase Dnl4p associated with its cofactor Lif1p. NHEJ efficiency is down-regulated in MATa/MATalpha cells relative to MATa or MATalpha cells, but the mechanism of this mating type regulation is unknown. Here we report the identification of Lif2p, a S. cerevisiae protein that interacts with Lif1p in a two-hybrid system. Disruption of LIF2 abolishes the capacity of cells to repair DSBs by end-joining to the same extent than lif1 and dnl4 mutants. In MATa/MATalpha cells, Lif2p steady-state level is strongly repressed when other factors involved in NHEJ are unaffected. Increasing the dosage of the Lif2p protein can suppress the NHEJ defect in a/alpha cells. Together, these results indicate that NHEJ regulation by mating type is achieved, at least in part, by a regulation of Lif2p activity.
Frank-Vaillant
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Laboratoire du cycle cellulaire, Service de biochimie et de génétique moléculaire, CEA/Saclay, 91191 Gif sur Yvette cedex, France.
Marcand
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D034961:Antigens, Nuclear; D001483:Base Sequence; D002470:Cell Survival; D003062:Codon; D004249:DNA Damage; D004265:DNA Helicases; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D019281:Dimerization; D015536:Down-Regulation; D005838:Genotype; D006238:Haploidy; D000072200:Ku Autoantigen; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism* / Q000502:physiology*; D020798:Two-Hybrid System Techniques
D034961:Antigens, Nuclear; D003062:Codon; D004268:DNA-Binding Proteins; C441270:NEJ1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C081647:high affinity DNA-binding factor, S cerevisiae; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D011088:DNA Ligases