These talks are intended for people who don't (necessarily) know anything about DNA and/or helicases. The first talk will cover basic background material on DNA and proteins which manage DNA. A helicase is one such protein; its job is to unwind the DNA double helix when the DNA must be copied, repaired, transcribed, etc. Ultimately, we will describe a simple model of DNA unwinding by helicases and what can be predicted about it.
Helicase opening of double-stranded nucleic acids may be active (the helicase directly destabilizes the dsNA to promote opening) or passive (the helicase binds ssNA available due to a thermal fluctuation which opens part of the dsNA). We describe helicase opening of dsNA, based on helicases which bind single NA strands and move towards the double-stranded region, using a discrete hopping model. The interaction between the helicase and the junction where the double strand opens is characterized by an interaction potential. The form of the potential determines whether the opening is active or passive. We calculate the rate of passive opening for the helicase PcrA, and show that the rate increases when the opening is active. Finally, we examine how to choose the interaction potential to optimize the rate of strand separation. One important result is our finding that active opening can increase the unwinding rate by 7 fold compared to passive opening.