E. coli Replication Origin. The E. coli replication origin oriC is an ≈240-bp DNA segment present at the start site for replication of E. coli chromosomal DNA. Plasmids or any other circular DNA containing oriC are capable of independent and controlled replication in E. coli cells.. coli Replication Origin. The E. coli replication origin oriC is an ≈240-bp DNA segment present at the start site for replication of E. coli chromosomal DNA. Plasmids or any other circular DNA containing oriC are capable of independent and controlled replication in E. coli cells.