Aggregated dnaA protein is dissociated and activated for DNA replication by phospholipase or dnaK protein

dnaA protein isolated from Escherichia coli is equally distributed between a monomeric form, which is active for initiation of DNA replication, and an inactive, aggregated form which contains phospholipids. Replication activity of the aggregated form can be restored by treatments with either dnaK protein or phospholipase A2. Dissociation of the aggregate by dnaK protein is driven by ATP hydrolysis; action by phospholipase A2 requires a minute concentration of ATP only to stabilize the dissociated protein. Conversion of inactive dnaA-phospholipid complexes to the active form may contribute to the regulation of the initiation of chromosomal replication in E. coli.