1. Inhibition of MRN activity by a telomere protein motif.
- Author
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Khayat F, Cannavo E, Alshmery M, Foster WR, Chahwan C, Maddalena M, Smith C, Oliver AW, Watson AT, Carr AM, Cejka P, and Bianchi A
- Subjects
- Amino Acid Sequence, DNA Breaks, Double-Stranded, DNA End-Joining Repair, DNA Helicases genetics, DNA, Fungal genetics, DNA, Fungal metabolism, Endodeoxyribonucleases genetics, Exodeoxyribonucleases genetics, Genomic Instability, Intracellular Signaling Peptides and Proteins genetics, Intracellular Signaling Peptides and Proteins metabolism, Origin Recognition Complex genetics, Origin Recognition Complex metabolism, Protein Serine-Threonine Kinases genetics, Protein Serine-Threonine Kinases metabolism, Saccharomyces cerevisiae genetics, Saccharomyces cerevisiae Proteins genetics, Sequence Homology, Amino Acid, Telomere genetics, Telomere-Binding Proteins genetics, Telomere-Binding Proteins metabolism, Amino Acid Motifs, DNA Helicases metabolism, Endodeoxyribonucleases metabolism, Exodeoxyribonucleases metabolism, Saccharomyces cerevisiae metabolism, Saccharomyces cerevisiae Proteins metabolism, Telomere metabolism
- Abstract
The MRN complex (MRX in Saccharomyces cerevisiae, made of Mre11, Rad50 and Nbs1/Xrs2) initiates double-stranded DNA break repair and activates the Tel1/ATM kinase in the DNA damage response. Telomeres counter both outcomes at chromosome ends, partly by keeping MRN-ATM in check. We show that MRX is disabled by telomeric protein Rif2 through an N-terminal motif (MIN, MRN/X-inhibitory motif). MIN executes suppression of Tel1, DNA end-resection and non-homologous end joining by binding the Rad50 N-terminal region. Our data suggest that MIN promotes a transition within MRX that is not conductive for endonuclease activity, DNA-end tethering or Tel1 kinase activation, highlighting an Achilles' heel in MRN, which we propose is also exploited by the RIF2 paralog ORC4 (Origin Recognition Complex 4) in Kluyveromyces lactis and the Schizosaccharomyces pombe telomeric factor Taz1, which is evolutionarily unrelated to Orc4/Rif2. This raises the possibility that analogous mechanisms might be deployed in other eukaryotes as well.
- Published
- 2021
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