(209h) Structure and Osmotic Properties of DNA in Lambda Bacteriophages

Based on a new DNA model, we apply a non-local density functional theory to describe the behavior of DNA in Lambda bacteriophages. The short-range repulsion, van der Waals attraction, Coulomb energy and chain connectivity correlation are taken into account explicitly. Besides the reproduction of osmotic properties in both bulk and Lambda heads, we also predict the packing morphology of DNA in Lambda phages with different genome lengths. It is shown that the DNA arrangement is determined by the competition between electrostatic screening and excluded-volume effects. For short length most DNA segments are located in the capsid central region with disordered pattern due to efficient neutralization of self-repulsion among negatively charged DNA segments by divalent counterions. In contrast, for long length the DNA forms long-range ordered multi-layer structure near the cage surface with a tightly packed outer one and much looser successive others, which is attributed to the domination of excluded-volume effects.