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The regulatory protein, cofilin, severs actin filaments and increases the number of ends from which subunits add and dissociate. Structural and biochemical analyses demonstrate that cofilin binding alters the conformation and mechanics of actin filaments such that cofilin-decorated filaments are~ 20-fold more compliant in bend and twist than native actin filaments. Equilibrium and kinetic binding models as well as direct visualization of cofilin binding to filaments favor a mechanism in which severing occurs at or near boundaries of bare and cofilin-decorated segments. It is hypothesized that shear stress associated with conformational fluctuations accumulates locally at boundaries of mechanical asymmetry, thereby leading to preferential severing at junctions of bare and cofilin-decorated segments. In this work, we evaluate if mechanical and conformational periodicity in filaments promotes stress accumulation at …