Helicase Unwinding of dsDNA: Velocity, Processivity, and Collective Effects

Wednesday, September 19, 2007 - 10:30am - 11:30am
EE/CS 3-180
Meredith Betterton (University of Colorado)
Helicases are molecular motors which unwind double-stranded nucleic
acids. Many helicases move with directional bias on single strands,
and couple directional translocation to strand separation. We describe
a theory of the coupling between translocation and unwinding, which
uses an interaction potential to represent passive and active helicase
mechanisms. Varying the interaction potential to represent passive or
active opening alters the predicted unwinding velocity and
processivity of a helicase. We describe the model predictions for the
dependence on the interaction potential, helicase step size, and
average base-pair binding free energy. New theoretical results on
unwinding by multiple interacting helicases are compared to
experimental data from the Antoine van Oijen lab, which suggest
unwinding by multiple helicases can show a higher apparent velocity
and processivity.