Jon M. Kaguni

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Initiation of DNA replication at the Escherichia coli chromosomal origin occurs through an ordered series of events that depends first on the binding of DnaA protein, the replication initiator, to DnaA box sequences followed by unwinding of an AT-rich region. A step that follows is the binding of DnaB helicase at oriC so that it is properly positioned at(More)
Escherichia coli is a model system to study the mechanism of DNA replication and its regulation during the cell cycle. One regulatory pathway ensures that initiation of DNA replication from the chromosomal origin, oriC, is synchronous and occurs at the proper time in the bacterial cell cycle. A major player in this pathway is SeqA protein and involves its(More)
An enzyme system that replicates plasmids bearing the origin of the Escherichia coli chromosomes (oriC) has the following physiologically relevant features. The system (i) depends completely on low levels of exogenously furnished supercoiled oriC plasmids, (ii) uses only those plasmids that contain the intact oriC region of about 245 base pairs, (iii)(More)
DnaA protein of Escherichia coli acts in the initiation of chromosomal replication to bind to sequences in the chromosomal origin. On binding, it promotes the assembly of other replication proteins that serve to prime DNA replication and assemble the replication apparatus for bidirectional replication fork movement. A collection of monoclonal antibodies to(More)
Initiation of DNA replication at the Escherichia coli chromosomal origin, oriC, occurs through an ordered series of events that depend first on the binding of DnaA protein, the replication initiator, to DnaA box sequences within oriC followed by unwinding of an AT-rich region near the left border. The prepriming complex then forms, involving the binding of(More)
Escherichia coli DnaC protein bound to ATP forms a complex with DnaB protein. To identify the domain of DnaC that interacts with DnaB, a genetic selection was used based on the lethal effect of induced dnaC expression and a model that inviability arises by the binding of DnaC to DnaB to inhibit replication fork movement. The analysis of dnaC alleles that(More)
Loading of the replicative DNA helicase at origins of replication is of central importance in DNA replication. As the first of the replication fork proteins assemble at chromosomal origins of replication, the loaded helicase is required for the recruitment of the rest of the replication machinery. In this work, we review the current knowledge of helicase(More)
A crude soluble enzyme system capable of authentic replication of a variety of oriC plasmids has been replaced by purified proteins constituting three functional classes: initiation proteins (RNA polymerase, dnaA protein, gyrase) that recognize the oriC sequence and presumably prime the leading strand of the replication fork; replication proteins (DNA(More)
Elevated dnaA expression from a multicopy plasmid induces more frequent initiation from the Escherichia coli replication origin, oriC, but viability is maintained. In comparison, chromosomally encoded dnaAcos also stimulates initiation, but this is lethal. By quantitative methods, we show that the level of initiation induced by elevated dnaA expression(More)