1 A COMMON MECHANISM FOR THE ATP-DnaA–DEPENDENT FORMATION OF OPEN COMPLEXES AT THE REPLICATION ORIGIN

Initiation of chromosomal replication and its cell cycle–coordinated regulation bear crucial and fundamental mechanisms in most cellular organisms. Escherichia coli DnaA protein forms a homomultimeric complex with the replication origin (oriC). ATP-DnaA multimers unwind the duplex within the oriC unwinding element (DUE). In this study, structural analyses suggested that several residues exposing in the central pore of the putative structure of DnaA multimers could be important for unwinding. Using mutation analyses, we found that, of these candidate residues, DnaA Val-211 and Arg-245 are prerequisite for initiation in vivo and in vitro