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Strand‐specific loading of DnaB helicase by DnaA to a substrate mimicking unwound oriC
Author(s) -
Weigel Christoph,
Seitz Harald
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.03232.x
Subject(s) - dnaa , dnab helicase , biology , helicase , prokaryotic dna replication , circular bacterial chromosome , dna replication , dna , origin of replication , microbiology and biotechnology , biophysics , genetics , gene , rna
Summary 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.