Negative control of replication initiation by a novel chromosomal locus exhibiting exceptional affinity for Escherichia coli DnaA protein

AUTOR(ES)

Kitagawa, Risa

FONTE

Cold Spring Harbor Laboratory Press

RESUMO

Replication of the Escherichia coli chromosome is initiated at a unique site, oriC. Concurrent initiation occurs at all oriC sites present in a cell once, and only once, per cell cycle. A mechanism to ensure cyclic initiation events was found operating through the chromosomal site, datA, a 1-kb segment located at 94.7 min on the genetic map that titrates exceptionally large amounts of the bacterial initiator protein, DnaA. A strain lacking datA grew normally but exhibited an asynchronous initiation phenotype as a result of extra initiation events. This mutant phenotype was suppressed by DnaA-titrating plasmids. Furthermore, mutations in a 9-bp DnaA-binding sequence (the DnaA box) in datA were enough to induce the mutant phenotype. Thus, datA is a novel chromosomal element that appears to adjust a balance between free and bound DnaA for a single initiation event at a fixed time in the bacterial cell cycle. Titration of DnaA to newly duplicated datA during oriC sequestration, which is mediated by hemimethylated GATC sequences in oriC and the SeqA protein, would contribute to prevention of reinitiations when oriC is desequestered.

Documentos Relacionados

• Purified dnaA protein in initiation of replication at the Escherichia coli chromosomal origin of replication.
• Membrane attachment activates dnaA protein, the initiation protein of chromosome replication in Escherichia coli.
• Coordination of chromosome replication initiation in Escherichia coli: effects of different dnaA alleles.
• Cooperation of the prs and dnaA gene products for initiation of chromosome replication in Escherichia coli.
• Expression of accumulated capacity for initiation of chromosome and minichromosome replication in dnaA mutants of Escherichia coli.