title: PCNA and Msh2-Msh6 activate an Mlh1-Pms1 endonuclease pathway required for Exo1-independent mismatch repair.
abstract: Genetic evidence has implicated multiple pathways in eukaryotic DNA mismatch repair (MMR) downstream of mispair recognition and Mlh1-Pms1 recruitment, including Exonuclease 1 (Exo1)-dependent and -independent pathways. We identified 14 mutations in POL30, which encodes PCNA in Saccharomyces cerevisiae, specific to Exo1-independent MMR. The mutations identified affected amino acids at three distinct sites on the PCNA structure. Multiple mutant PCNA proteins had defects either in trimerization and Msh2-Msh6 binding or in activation of the Mlh1-Pms1 endonuclease that initiates excision during MMR. The latter class of mutations led to hyperaccumulation of repair intermediate Mlh1-Pms1 foci and were enhanced by an msh6 mutation that disrupted the Msh2-Msh6 interaction with PCNA. These results reveal a central role for PCNA in the Exo1-independent MMR pathway and suggest that Msh2-Msh6 localizes PCNA to repair sites after mispair recognition to activate the Mlh1-Pms1 endonuclease for initiating Exo1-dependent repair or for driving progressive excision in Exo1-independent repair.
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors: Eva M
authors: EM
authors: Goellner
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors: Catherine E
authors: CE
authors: Smith
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors: Christopher S
authors: CS
authors: Campbell
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
authors: Hans
authors: H
authors: Hombauer
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors: Arshad
authors: A
authors: Desai
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA.
authors: Christopher D
authors: CD
authors: Putnam
authors: Ludwig Institute for Cancer Research, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Moores-UCSD Cancer Center, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA; Institute of Genomic Medicine, University of California, San Diego School of Medicine, La Jolla, CA 92093-0669, USA. Electronic address: rkolodner@ucsd.edu.
authors: Richard D
authors: RD
authors: Kolodner
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D053843:DNA Mismatch Repair; D004271:DNA, Fungal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D008958:Models, Molecular; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D051718:MutS Homolog 2 Protein / Q000378:metabolism*; D020125:Mutation, Missense; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D055550:Protein Stability; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; C088859:MLH1 protein, S cerevisiae; C098790:MSH6 protein, S cerevisiae; C088858:PMS1 protein, S cerevisiae; C546594:POL30 protein, S cerevisiae; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I; C489751:MSH2 protein, S cerevisiae; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D051718:MutS Homolog 2 Protein