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Figure 6.
Figure 6. Model for DnaC/DnaA Crosstalk and Helicase
Deposition
(A) Structural model for oligomeric DnaC:DnaA
interactions. The figure was generated by superimposing the last
subunit of a six-subunit DnaC[AAA+] oligomer onto the end of a
twelve-subunit DnaA filament assembly. Axial and side views are
shown. Cyan spheres represent bound nucleotide.
(B) Model
for the symmetric loading of two replicative helicases at oriC.
Left: DnaA assembles at oriC and melts the DUE (purple strands).
Middle, (1): helicase loading on the bottom DUE strand is
facilitated through direct DnaA:DnaB interaction. Middle, (2):
DnaC, through a specific interaction with ATP-charged DnaA,
recruits the helicase destined for the top strand to oriC.
Right: ATP hydrolysis and loss of DnaC frees both DnaB hexamers
to migrate to their proper fork positions.
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