Figure 1
From: oriD structure controls RepD initiation during rolling-circle replication
The rolling circle plasmid replication (i) The initiator protein (RepD, green) nicks DNA at the site of double-stranded origin oriD making a covalent complex with DNA. (ii & iii) PcrA helicase (orange) binds the exposed section of single-stranded DNA, unwinding the parent plasmid DNA allowing DNA polymerase III (blue) to commence synthesis of a new DNA strand (red strand). (iv) After DNA synthesis has proceeded all the way around the plasmid, reaching the region of oriD, replication is terminated, RepD is released along with the single-stranded DNA which is then replicated by another round of DNA synthesis. (v) Finally, the two newly synthesized daughter plasmids are supercoiled by DNA gyrase so that further rounds of replication may proceed.
