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. 2013 Jul 18;9(7):e1003623. doi: 10.1371/journal.pgen.1003623

Figure 5. Cartoon of repeated rolling-circle replication from the ICEBs1 oriT that is stuck in the chromosome.

Figure 5

Rolling circle replication is induced in ICEBs1 insertions that are unable to excise from the chromosome. During this replication, the ICEBs1 relaxase NicK (black circles) nicks a site in oriT, the origin of transfer (gray bar) that also functions as an origin of replication [15], [23]. NicK presumably becomes covalently attached to the 5′ end of the nicked DNA. Replication extends (dotted line with arrow) from the free 3′-end, and regenerates a functional oriT that is a substrate for another molecule of NicK. The only other ICEBs1 product needed for ICEBs1 replication is the helicase processivity factor HelP [19]. The rest of the replication machinery (not shown) is composed of host-encoded proteins.