Random Knotting and Viral DNA Packing: Theory and Experiments

Computational and Applied Mathematics Colloquium

Meeting Details

For more information about this meeting, contact Hope Shaffer, Jinchao Xu, Kris Jenssen.

Speaker: DeWitt Sumners, Florida State University

Abstract: At the interface between statistical mechanics and topology, one encounters the very interesting problem of length dependence of the spectrum of topological properties (knotting, linking, writhing, etc.) of randomly embedded circles in 3-space. This talk will discuss the proof and some generalizations of the Frisch-Wasserman-Delbruck conjecture: the longer a random circle, the more likely it is to be knotted. As application, we will consider the packing geometry of DNA in viral capsids. Bacteriophages are viruses that infect bacteria. They pack their double-stranded DNA genomes to near-crystalline density in viral capsids and achieve one of the highest levels of DNA condensation found in nature. Despite numerous studies some essential properties of the packaging geometry of the DNA inside the phage capsid are still unknown. Although viral DNA is linear double-stranded with sticky ends, the linear viral DNA quickly becomes cyclic when removed from the capsid, and for some viral DNA the observed knot probability is an astounding 95%. This talk will discuss comparison of the observed viral knot spectrum with the simulated knot spectrum, concluding that the packing geometry of the DNA inside the capsid is non-random and writhe-directed.

Room Reservation Information

Room Number: 106 McAllister

Date: 02/15/2008

Time: 3:35pm - 4:25pm