Domain separation and characterization of P ri C , a replication restart primosome factor in E scherichia coli

In E scherichia coli the ori C ‐independent primosome plays an essential role in replication restart after dissociation of the replication DNA –protein complex by DNA damage. Primosome is thought to form via two pathways: one P ri A dependent and the other P ri A independent. P ri C is a key protein in the replication restart of the P ri A ‐independent pathway. In this study, we determined that P ri C was divided into two domains. Then, we obtained information that: (i) the C ‐terminal domain preferentially binds to single‐stranded DNA (ss DNA ); (ii) the binding of P ri C to ss DNA depends on salt concentration; and (iii) the binding site size of P ri C is approximately 7–9 nucleotides. The protease digestion of P ri C suggested that a possible DNA ‐binding site is the N ‐terminus of the C ‐terminal domain where basic amino acid residues are concentrated. Interestingly, α‐helical induction of the C ‐terminal domain of P ri C occurred after the addition of DNA s. Also, we examined the role of heptad repeat of leucine or valine residues in the C ‐terminal domain and P ri C oligomerization. This study describes the structure and function analysis of P ri C which forms the primosome complex in replication restart.