title: The sliding clamp tethers the endonuclease domain of MutL to DNA.
abstract: The sliding clamp enhances polymerase processivity and coordinates DNA replication with other critical DNA processing events including translesion synthesis, Okazaki fragment maturation and DNA repair. The relative binding affinity of the sliding clamp for its partners determines how these processes are orchestrated and is essential to ensure the correct processing of newly replicated DNA. However, while stable clamp interactions have been extensively studied; dynamic interactions mediated by the sliding clamp remain poorly understood. Here, we characterize the interaction between the bacterial sliding clamp (β-clamp) and one of its weak-binding partners, the DNA mismatch repair protein MutL. Disruption of this interaction causes a mild mutator phenotype in Escherichia coli, but completely abrogates mismatch repair activity in Bacillus subtilis. We stabilize the MutL-β interaction by engineering two cysteine residues at variable positions of the interface. Using disulfide bridge crosslinking, we have stabilized the E. coli and B. subtilis MutL-β complexes and have characterized their structures using small angle X-ray scattering. We find that the MutL-β interaction greatly stimulates the endonuclease activity of B. subtilis MutL and supports this activity even in the absence of the N-terminal region of the protein.
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
authors.forename: Monica C
authors.initials: MC
authors.lastname: Pillon
authors.affiliation: Department of Biochemistry, The School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, 14214, USA Witebsky Center for Microbial Pathogenesis and Immunology, The School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, 14214, USA.
authors.forename: Vignesh M P
authors.initials: VM
authors.lastname: Babu
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor MI 48109, USA.
authors.forename: Justin R
authors.initials: JR
authors.lastname: Randall
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada.
authors.forename: Jiudou
authors.initials: J
authors.lastname: Cai
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor MI 48109, USA.
authors.forename: Lyle A
authors.initials: LA
authors.lastname: Simmons
authors.affiliation: Department of Biochemistry, The School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, 14214, USA Witebsky Center for Microbial Pathogenesis and Immunology, The School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, 14214, USA Genetics, Genomics and Bioinformatics Program, The School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, 14214, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Sutton
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S 4K1, Canada guarnea@mcmaster.ca.
authors.forename: Alba
authors.initials: A
authors.lastname: Guarné
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001412:Bacillus subtilis / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003545:Cysteine / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004258:DNA Polymerase III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D000070956:MutL Proteins; D011485:Protein Binding; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D004247:DNA; C101139:beta subunit, DNA polymerase III; D004258:DNA Polymerase III; D004706:Endodeoxyribonucleases; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins; D003545:Cysteine