DNAA PROTEIN DIRECTS THE BINDING OF DNAB PROTEIN IN INITIATION OF DNA-REPLICATION IN ESCHERICHIA-COLI

DnaA protein of Escherichia coli acts in the initiation of chromosomal replication to bind to sequences in the chromosomal origin. On bindin g, it promotes the assembly of other replication proteins that serve t o prime DNA replication and assemble the replication apparatus for bid irectional replication fork movement. A collection of monoclonal antib odies to DnaA protein have been produced, one of which is described he re, that interferes with the action of DnaA protein in promoting forma tion of a prepriming complex. On the analysis of this process, the ant ibody appears to interfere with the physical interaction between DnaA and DnaB protein in the DnaB.DnaC complex. Cross-linking studies confi rm that DnaA and DnaB proteins interact directly These results provide the first direct evidence that one of the roles of DnaA protein is to act as a site for binding of DnaB protein to the DNA and perhaps orie nts DnaB helicase to account for the directionality of replication for k movement.