title: Structural and biochemical analysis of sliding clamp/ligand interactions suggest a competition between replicative and translesion DNA polymerases.
abstract: Most DNA polymerases interact with their cognate processive replication factor through a small peptide, this interaction being absolutely required for their function in vivo. We have solved the crystal structure of a complex between the beta sliding clamp of Escherichia coli and the 16 residue C-terminal peptide of Pol IV (P16). The seven C-terminal residues bind to a pocket located at the surface of one beta monomer. This region was previously identified as the binding site of another beta clamp binding protein, the delta subunit of the gamma complex. We show that peptide P16 competitively prevents beta-clamp-mediated stimulation of both Pol IV and alpha subunit DNA polymerase activities, suggesting that the site of interaction of the alpha subunit with beta is identical with, or overlaps that of Pol IV. This common binding site for delta, Pol IV and alpha subunit is shown to be formed by residues that are highly conserved among many bacterial beta homologs, thus defining an evolutionarily conserved hydrophobic crevice for sliding clamp ligands and a new target for antibiotic drug design.
authors.affiliation: UPR 9003 CNRS, IRCAD, 1 place de l'Hôpital, BP 424, 67091 Strasbourg, France. dominique.burnouf@ircad.u-strasbg.fr
authors.forename: Dominique Y
authors.initials: DY
authors.lastname: Burnouf
authors.forename: Vincent
authors.initials: V
authors.lastname: Olieric
authors.forename: Jérôme
authors.initials: J
authors.lastname: Wagner
authors.forename: Shingo
authors.initials: S
authors.lastname: Fujii
authors.forename: J
authors.initials: J
authors.lastname: Reinbolt
authors.forename: Robert P P
authors.initials: RP
authors.lastname: Fuchs
authors.forename: Philippe
authors.initials: P
authors.lastname: Dumas
mesh_terms: D001667:Binding, Competitive; D003460:Crystallization; D004256:DNA Polymerase I / Q000378:metabolism; D004258:DNA Polymerase III / Q000378:metabolism; D019951:DNA Polymerase beta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D010446:Peptide Fragments / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D008024:Ligands; D010446:Peptide Fragments; D018809:Proliferating Cell Nuclear Antigen; D021122:Protein Subunits; D011994:Recombinant Proteins; D004256:DNA Polymerase I; D004258:DNA Polymerase III; D019951:DNA Polymerase beta