title: The Mismatch-Binding Factor MutSβ Can Mediate ATR Activation in Response to DNA Double-Strand Breaks.
abstract: Ataxia telangiectasia-mutated and Rad3-related (ATR) protein kinase, a master regulator of DNA-damage response, is activated by RPA-coated single-stranded DNA (ssDNA) generated at stalled replication forks or DNA double-strand breaks (DSBs). Here, we identify the mismatch-binding protein MutSβ, a heterodimer of MSH2 and MSH3, as a key player in this process. MSH2 and MSH3 form a complex with ATR and its regulatory partner ATRIP, and their depletion compromises the formation of ATRIP foci and phosphorylation of ATR substrates in cells responding to replication-associated DSBs. Purified MutSβ binds to hairpin loop structures that persist in RPA-ssDNA complexes and promotes ATRIP recruitment. Mutations in the mismatch-binding domain of MSH3 abolish the binding of MutSβ to DNA hairpin loops and its ability to promote ATR activation by ssDNA. These results suggest that hairpin loops might form in ssDNA generated at sites of DNA damage and trigger ATR activation in a process mediated by MutSβ.
authors.affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 142 20 Prague 4, Czech Republic.
authors.forename: Kamila
authors.initials: K
authors.lastname: Burdova
authors.affiliation: Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Boris
authors.initials: B
authors.lastname: Mihaljevic
authors.affiliation: Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Sturzenegger
authors.affiliation: Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
authors.forename: Nagaraja
authors.initials: N
authors.lastname: Chappidi
authors.affiliation: Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, 142 20 Prague 4, Czech Republic; Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland. Electronic address: pjanscak@imcr.uzh.ch.
authors.forename: Pavel
authors.initials: P
authors.lastname: Janscak
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation; D057809:HEK293 Cells; D059765:Homologous Recombination; D006801:Humans; D051718:MutS Homolog 2 Protein / Q000737:chemistry / Q000502:physiology*; D000074081:MutS Homolog 3 Protein; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021381:Protein Transport
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C078444:MSH3 protein, human; D000074081:MutS Homolog 3 Protein; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein