title: IHF and HU stimulate assembly of pre-replication complexes at Escherichia coli oriC by two different mechanisms.
abstract: Pre-replication complexes (pre-RC) assemble on replication origins and unwind DNA in the presence of chromatin proteins. As components of Escherichia coli pre-RC, two histone-like proteins HU and IHF (integration host factor), stimulate initiator DnaA-catalysed unwinding of the chromosomal replication origin, oriC. Using in vivo footprint analysis just before DNA synthesis initiates, we detect IHF binding coincident with a shift of DnaA to weaker central oriC sites. Integration host factor redistributed pre-bound DnaA to identical sites in vitro. HU did not redistribute DnaA, but suppressed binding specifically at I3. These results suggest that different pathways mediated by bacterial chromatin proteins exist to regulate pre-RC assembly and unwind oriC.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D034982:Integration Host Factors / Q000378:metabolism*; D008969:Molecular Sequence Data; D051738:Origin Recognition Complex; D018741:Replication Origin / Q000502:physiology; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D034982:Integration Host Factors; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; D014764:Viral Proteins; C040330:histone-like protein HU, bacteria