Effects of osmotic stress on DNA packing and capsid stability in simple viruses – Rudi Podgornik

Date: Thu. January 21st, 2010, 4:15 pm-5:15 pm
Location: Rockefeller 301

I will address the problem of DNA packing in the bacteriophage capsid. I will show that it can be formulated in the framewrok of a liquid crystalline nematic nanodrop model. The elastic equilibrium condition can be written as a first intergral of the EL equations and gives the elastic stresses in the system. Solving the first integral for the DNA density field leads to the encapsidation equation of state that compares well with osmotic stress experiments and predicts the ejection characteristics in the presence of polyvalent counterions. I will also discuss the effects of osmotic stress on empty viral capsids and show that there exists a critcal value of the osmotic stress that destabilizes the capsid. The rupture scenario is quite complicated but depends on a single dimensionless parameter.