Dataset S1. Psuedo Code for an Actin Filament
(29 KB DOC).
Dataset S2. Steady-State Number of ActA–Arp2/3 Complexes on the Bacterium
(52 KB DOC).
Video S1. One Actin Filament Interacting with the Bacterium
A close-up look at the interaction of a single polymerizing filament with the bacterium. This filament has an artificially durable link with an ActA protein on the bacterium's surface; these links are typically very transient. The tip-clearance (drawn with a cyan line), the polymerization probability, the capping probability, and the Arp2/3 binding probability (set to zero for this demonstration) are reported at each simulation time-step.
(1 MB MOV).
Video S2. An Animated Simulation: Motion Initiation and Persistence
An animation rendered from the output of one simulation of L. monocytogenes motility. Microscale hops, as opposed to the nanoscale steps we investigate in this paper, are apparent at this scale view. The bacterium induces an actin tail of variable density and demonstrates persistent motion.
(9.8 MB MOV).
Acknowledgments
We thank Julie Theriot, Bruce Alberts, and members of the Center for Cell Dynamics (www.celldynamics.org) for comments on the focus of this model and content of this manuscript, Susanne Rafelski for measurements of ActA distributions, and Paul Mutton for Java EPS figure generation freeware. Initial conception and development of this work was supported by a postdoctoral fellowship in computational biology from the Alfred P. Sloan Foundation (JBA); for that unique opportunity to “cross over” from engineering to biological modeling JBA is especially grateful. This work was further funded by the National Institutes of Health grant NIGMS 5P50 GM 666050-02 (JBA and GMO).
Conflicts of interest. The authors have declared that no conflicts of interest exist.
Author contributions. JBA and GMO conceived and designed the experiments. JBA performed the experiments. JBA and GMO analyzed the data. JBA and GMO wrote the paper.
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