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arXiv · 0911.1064

Cooperativity and Frustration in Protein-Mediated Parallel Actin Bundles

Homin Shin·Kirstin R. Purdy Drew·James R. Bartles·Gerard C. L. Wong·Gregory M. Grason
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Abstract

We examine the mechanism of bundling of cytoskeletal actin filaments by two representative bundling proteins, fascin and espin. Small-angle X-ray studies show that increased binding from linkers drives a systematic \textit{overtwist} of actin filaments from their native state, which occurs in a linker-dependent fashion. Fascin bundles actin into a continuous spectrum of intermediate twist states, while espin only allows for untwisted actin filaments and fully-overtwisted bundles. Based on a coarse-grained, statistical model of protein binding, we show that the interplay between binding geometry and the intrinsic \textit{flexibility} of linkers mediates cooperative binding in the bundle. We attribute the respective continuous/discontinous bundling mechanisms of fascin/espin to differences in the stiffness of linker bonds themselves.

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Homin Shin, Kirstin R. Purdy Drew, James R. Bartles, Gerard C. L. Wong, Gregory M. Grason. 2009-11-06. Cooperativity and Frustration in Protein-Mediated Parallel Actin Bundles. https://doi.org/10.1103/physrevlett.103.238102

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