title: Dynamic control of strand excision during human DNA mismatch repair.
abstract: Mismatch repair (MMR) is activated by evolutionarily conserved MutS homologs (MSH) and MutL homologs (MLH/PMS). MSH recognizes mismatched nucleotides and form extremely stable sliding clamps that may be bound by MLH/PMS to ultimately authorize strand-specific excision starting at a distant 3'- or 5'-DNA scission. The mechanical processes associated with a complete MMR reaction remain enigmatic. The purified human (Homo sapien or Hs) 5'-MMR excision reaction requires the HsMSH2-HsMSH6 heterodimer, the 5' → 3' exonuclease HsEXOI, and the single-stranded binding heterotrimer HsRPA. The HsMLH1-HsPMS2 heterodimer substantially influences 5'-MMR excision in cell extracts but is not required in the purified system. Using real-time single-molecule imaging, we show that HsRPA or Escherichia coli EcSSB restricts HsEXOI excision activity on nicked or gapped DNA. HsMSH2-HsMSH6 activates HsEXOI by overcoming HsRPA/EcSSB inhibition and exploits multiple dynamic sliding clamps to increase tract length. Conversely, HsMLH1-HsPMS2 regulates tract length by controlling the number of excision complexes, providing a link to 5' MMR.
authors.affiliation: Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea;
authors.forename: Yongmoon
authors.initials: Y
authors.lastname: Jeon
authors.affiliation: Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea;
authors.forename: Daehyung
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Medical Center, Columbus, OH 43210;
authors.forename: Juana V
authors.initials: JV
authors.lastname: Martín-López
authors.affiliation: Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea;
authors.forename: Ryanggeun
authors.initials: R
authors.lastname: Lee
authors.affiliation: Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea;
authors.forename: Jungsic
authors.initials: J
authors.lastname: Oh
authors.affiliation: Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Medical Center, Columbus, OH 43210;
authors.forename: Jeungphill
authors.initials: J
authors.lastname: Hanne
authors.affiliation: Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Medical Center, Columbus, OH 43210; Department of Physics, The Ohio State University, Columbus, OH 43210; rfishel@osu.edu jblee@postech.ac.kr.
authors.forename: Richard
authors.initials: R
authors.lastname: Fishel
authors.affiliation: Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Korea; Interdisciplinary Bioscience and Bioengineering, POSTECH, Pohang, 790-784, Korea rfishel@osu.edu jblee@postech.ac.kr.
authors.forename: Jong-Bong
authors.initials: JB
authors.lastname: Lee
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D020137:Base Pair Mismatch; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D000070957:MutL Protein Homolog 1; D045643:DNA Repair Enzymes
keywords: EXOI; Lynch syndrome/HNPCC; MLH1–PMS2; MSH2–MSH6; single molecule