Disassembly of fascin bundled actin filaments via their Mical associated oxidation.

Actin filaments are the major component of cellular substructures involved in cell motility and cell sensing, depending on the cues from the microenvironment. Actin's diverse functions are enabled by its transitions from a monomeric (G-actin) to filamentous (F-actin) form, which in turn can be converted into higher order structures, like bundles, with the help of various actin-crosslinking proteins. The mechanism of actin bundles formation has been previously reported, but how they disassemble is understood less well. Using real-time solution-based assays and purified proteins we try to unravel the specific mechanism by which the MICAL family of monooxygenase induces the disassembly of bundled actin. These experiments were further supported by our in vivo studies using a model cellular system. We showed that the rate of disassembly is enhanced upon addition of cofilin, a well-known F-actin severing protein. Overall, our results shed new light on the mechanism of actin bundle disassembly and its direct impact on cellular remodeling.