title: The bacteriophage phi 29 DNA polymerase, a proofreading enzyme.
abstract: The bacteriophage phi 29 DNA polymerase, involved both in the protein-primed initiation and elongation steps of the viral DNA replication, displays a very processive 3',5'-exonuclease activity acting preferentially on single-stranded DNA. This exonucleolytic activity showed a marked preference for excision of a mismatched versus a correctly paired 3' terminus. These characteristics enable the phi 29 DNA polymerase to act as a proofreading enzyme. A comparative analysis of the wild-type phi 29 DNA polymerase and a mutant lacking 3',5'-exonuclease activity indicated that a productive coupling between the exonuclease and polymerase activities is necessary to prevent fixation of polymerization errors. Based on these data, the phi 29 DNA polymerase, a model enzyme for protein-primed DNA replication, appears to share the same mechanism for the editing function as that first proposed for T4 DNA polymerase and Escherichia coli DNA polymerase I on the basis of functional and structural studies.
authors.affiliation: Centro de Biología Molecular (Consejo Superior de Investigacìones Científicas-UAM), Universidad Autónoma, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Garmendia
authors.forename: A
authors.initials: A
authors.lastname: Bernad
authors.forename: J A
authors.initials: JA
authors.lastname: Esteban
authors.forename: L
authors.initials: L
authors.lastname: Blanco
authors.forename: M
authors.initials: M
authors.lastname: Salas
mesh_terms: D001435:Bacteriophages / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000378:metabolism; D008969:Molecular Sequence Data; D013696:Temperature
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004259:DNA-Directed DNA Polymerase; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V