title: Inactivation of Individual SeqA Binding Sites of the E. coli Origin Reveals Robustness of Replication Initiation Synchrony.
abstract: The Escherichia coli origin of replication, oriC, comprises mostly binding sites of two proteins: DnaA, a positive regulator, and SeqA, a negative regulator. SeqA, although not essential, is required for timely initiation, and during rapid growth, synchronous initiation from multiple origins. Unlike DnaA, details of SeqA binding to oriC are limited. Here we have determined that SeqA binds to all its sites tested (9/11) and with variable efficiency. Titration of DnaA alters SeqA binding to two sites, both of which have overlapping DnaA sites. The altered SeqA binding, however, does not affect initiation synchrony. Synchrony is also unaffected when individual SeqA sites are mutated. An apparent exception was one mutant where the mutation also changed an overlapping DnaA site. In this mutant, the observed asynchrony could be from altered DnaA binding, as selectively mutating this SeqA site did not cause asynchrony. These results reveal robust initiation synchrony against alterations of individual SeqA binding sites. The redundancy apparently ensures SeqA function in controlling replication in E. coli.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America.
authors.forename: Jyoti K
authors.initials: JK
authors.lastname: Jha
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States of America.
authors.forename: Dhruba K
authors.identifier: http://orcid.org/0000-0002-9272-3673
authors.initials: DK
authors.lastname: Chattoraj
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015139:Blotting, Southern; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D016133:Polymerase Chain Reaction; D018741:Replication Origin / Q000235:genetics / Q000502:physiology
chemical_list: D001425:Bacterial Outer Membrane Proteins; C505237:Cnu protein, E coli; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C089746:SeqA protein, E coli