An elastic analysis of Listeria monocytogenes propulsion

The bacterium Listeria monocytogenes uses the energy of the actin polymeriz ation to propel itself through infected tissues. In steady state, it contin uously adds new polymerized filaments to its surface, pushing on its tail, which is made from previously cross-linked actin filaments. In this paper w e introduce an elastic model to describe how the addition of actin filament s to the tail results in the propulsive force on the bacterium. Filament gr owth on the bacterial surface produces stresses that are relieved at the ba ck of the bacterium as it moves forward. The model leads to a natural compe tition between growth from the sides and growth from the back of the bacter ium, with different velocities and strengths for each. This competition can lead to the periodic motion observed in a Listeria mutant.