title: Strand-specific loading of DnaB helicase by DnaA to a substrate mimicking unwound oriC.
abstract: We analysed the enzymatic activity (strand dis-placement) of the Escherichia coli DnaB helicase on a mirror-image pair of oligonucleotide-based substrates mimicking the unwound replication origin oriC. Loading of the helicase complex occurred exclusively to the single-stranded 'lower strand' part of the substrates. Full helicase activity required DnaA bound to the double-stranded part of the substrates (oriC DnaA box R1) and to their single-stranded 'upper strand' part. We assume that in vivo DnaA also loads the first of two helicase complexes - required for the assembly of two replication forks - to the lower strand of oriC during initiation of bidirectional chromosome replication in E. coli.
authors.affiliation: Max-Planck-Institut für molekulare Genetik, Berlin, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Weigel
authors.forename: Harald
authors.initials: H
authors.lastname: Seitz
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D053488:DnaB Helicases; D004926:Escherichia coli / Q000235:genetics; D008956:Models, Chemical; D008958:Models, Molecular; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry* / Q000378:metabolism*; D051738:Origin Recognition Complex; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D009841:Oligonucleotides; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; D014764:Viral Proteins; D004247:DNA; D004265:DNA Helicases; D053488:DnaB Helicases