title: Single DNA molecule jamming and history-dependent dynamics during motor-driven viral packaging.
abstract: In many viruses molecular motors forcibly pack single DNA molecules to near-crystalline density into ~50-100 nm prohead shells1, 2. Unexpectedly, we found that packaging frequently stalls in conditions that induce net attractive DNA-DNA interactions3. Here, we present findings suggesting that this stalling occurs because the DNA undergoes a nonequilibrium jamming transition analogous to that observed in many soft-matter systems, such as colloidal and granular systems4-8. Experiments in which conditions are changed during packaging to switch DNA-DNA interactions between purely repulsive and net attractive reveal strongly history-dependent dynamics. An abrupt deceleration is usually observed before stalling, indicating that a transition in DNA conformation causes an abrupt increase in resistance. Our findings suggest that the concept of jamming can be extended to a single polymer molecule. However, compared with macroscopic samples of colloidal particles5we find that single DNA molecules jam over a much larger range of densities. We attribute this difference to the nanoscale system size, consistent with theoretical predictions for jamming of attractive athermal particles.9, 10.
authors.affiliation: Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0379.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Keller
authors.affiliation: Department of Diagnostic and Biological Sciences and Institute for Molecular Virology, University of Minnesota, 515 Delaware Street SE, Minneapolis, MN 55455.
authors.forename: Shelley
authors.initials: S
authors.lastname: Grimes
authors.affiliation: Department of Diagnostic and Biological Sciences and Institute for Molecular Virology, University of Minnesota, 515 Delaware Street SE, Minneapolis, MN 55455.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Jardine
authors.affiliation: Department of Physics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0379.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Smith