Figure 6
From: Direct visualization of DNA baton pass between replication factors bound to PCNA
Possible mechanism of “passing DNA baton” during Okazaki fragment maturation. (a) The FEN-mediated flap cleavage occurs on PCNA by bending the DNA by about 100 degrees (this study). (b) The nicked dsDNA, generated by the action of FEN, becomes extended so that Lig contacts the DNA. FEN stays in the complex until Lig binds to the complex to form the “the handing-over” intermediate (this study). (c) After dissociation of FEN from the complex, Lig may form another open conformation with a small movement of the OBD towards DNA, as seen in the previous Lig-PCNA-DNA EM structure10. A further conformational change could occur so that Lig wraps around the DNA to form the active and closed conformation observed in the human Lig-DNA crystal structure (d). It is currently unclear whether PCNA remains loaded onto the DNA to support the ligation reaction by Lig.
