title: Structural determinant for switching between the polymerase and exonuclease modes in the PCNA-replicative DNA polymerase complex.
abstract: Proliferating cell nuclear antigen (PCNA) is responsible for the processivity of DNA polymerase. We determined the crystal structure of Pyrococcus furiosus DNA polymerase (PfuPol) complexed with the cognate monomeric PCNA, which allowed us to construct a convincing model of the polymerase-PCNA ring interaction, with unprecedented configurations of the two molecules. Electron microscopic analyses indicated that this complex structure exists in solution. Our structural study revealed that an interaction occurs between a stretched loop of PCNA and the PfuPol Thumb domain, in addition to the authentic PCNA-polymerase recognition site (PIP box). Comparisons of the present structure with the previously reported structures of polymerases complexed with DNA, suggested that the second interaction plays a crucial role in switching between the polymerase and exonuclease modes, by inducing a PCNA-polymerase complex configuration that favors synthesis over editing. This putative mechanism for fidelity control of replicative DNA polymerases is supported by experiments, in which mutations at the second interaction site caused enhancements in the exonuclease activity in the presence of PCNA.
authors.affiliation: Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nishida
authors.forename: Kouta
authors.initials: K
authors.lastname: Mayanagi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kiyonari
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sato
authors.forename: Takuji
authors.initials: T
authors.lastname: Oyama
authors.forename: Yoshizumi
authors.initials: Y
authors.lastname: Ishino
authors.forename: Kosuke
authors.initials: K
authors.lastname: Morikawa
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004247:DNA / Q000648:ultrastructure; D017931:DNA Primers / Q000378:metabolism; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000648:ultrastructure; D005092:Exonucleases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D020027:Pyrococcus furiosus / Q000201:enzymology*; D020349:Surface Plasmon Resonance
chemical_list: D017931:DNA Primers; D018809:Proliferating Cell Nuclear Antigen; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D005092:Exonucleases