Pre-priming complex (E. coli)

The pre-priming complex is formed, at the oriC, in the initiation phase of E. coli DNA replication.

The association of dnaB protein with oriC represents the first step at which binding of DNA a protein to the origin results in the assembly of replication enzymes for the initiation of DNA synthesis.

DnaB and dnaC protein form a complex, formed in solution with ATP.  The dnaA protein guides a dnaB - dnaC complex into the melted region to form a pre-priming complex.

The dnaC protein is not stably maintained in the complex, in which it inhibits the helicase activity of dnaB protein and so must be ejected for replication proceeds.

The pre-priming intermediate is stable, isolatable, and resistant to low temperature.