title: Evidence that the DNA mismatch repair system removes 1-nucleotide Okazaki fragment flaps.
abstract: The DNA mismatch repair (MMR) system plays a major role in promoting genome stability and suppressing carcinogenesis. In this work, we investigated whether the MMR system is involved in Okazaki fragment maturation. We found that in the yeast Saccharomyces cerevisiae, the MMR system and the flap endonuclease Rad27 act in overlapping pathways that protect the nuclear genome from 1-bp insertions. In addition, we determined that purified yeast and human MutSα proteins recognize 1-nucleotide DNA and RNA flaps. In reconstituted human systems, MutSα, proliferating cell nuclear antigen, and replication factor C activate MutLα endonuclease to remove the flaps. ATPase and endonuclease mutants of MutLα are defective in the flap removal. These results suggest that the MMR system contributes to the removal of 1-nucleotide Okazaki fragment flaps.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901.
authors.forename: Lyudmila Y
authors.initials: LY
authors.lastname: Kadyrova
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901.
authors.forename: Basanta K
authors.initials: BK
authors.lastname: Dahal
authors.affiliation: From the Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901 fkadyrov@siumed.edu.
authors.forename: Farid A
authors.initials: FA
authors.lastname: Kadyrov
mesh_terms: D004247:DNA / Q000737:chemistry / Q000235:genetics*; D053843:DNA Mismatch Repair; D004252:DNA Mutational Analysis; D045643:DNA Repair Enzymes / Q000378:metabolism*; D004261:DNA Replication; D004270:DNA, Circular / Q000737:chemistry; D045585:Flap Endonucleases / Q000235:genetics; D005656:Fungal Proteins / Q000378:metabolism; D017353:Gene Deletion; D016678:Genome; D006801:Humans; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein / Q000378:metabolism*; D009154:Mutation; D011003:Ploidies; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051818:Replication Protein C / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004270:DNA, Circular; D005656:Fungal Proteins; C500929:MutLalpha protein, human; C022262:Okazaki fragments; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D045585:Flap Endonucleases; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; D051818:Replication Protein C; D045643:DNA Repair Enzymes
keywords: DNA endonuclease; DNA mismatch repair; DNA replication; Okazaki fragment maturation; cancer; genomic instability; mutL homolog 1 (MLH1)