DOMAINS OF DNAA PROTEIN INVOLVED IN INTERACTION WITH DNAB PROTEIN, AND IN UNWINDING THE ESCHERICHIA-COLI CHROMOSOMAL ORIGIN

DnaA protein of Escherichia coli is a sequence-specific DNA-binding pr otein required for the initiation of DNA replication from the chromoso mal origin, oriC, It is also required for replication of several plasm ids including pSC101, F, P-1, and R6K. A collection of monoclonal anti bodies to DnaA protein has been produced and the primary epitopes reco gnized by them have been determined, These antibodies have also been e xamined for the ability to inhibit activities of DNA binding, ATP bind ing, unwinding of oriC, and replication of both an oriC plasmid, and a n M13 single-stranded DNA with a proposed hairpin structure containing a DnaA protein-binding site, Replication of the latter DNA is depende nt on DnaA protein by a mechanism termed ABC priming, These studies su ggest regions of DnaA protein involved in interaction with DnaB protei n, and in unwinding of oriC, or low-affinity binding of ATP.