Cofilin-induced changes in F-actin detected via cross-linking with benzophenone-4-maleimide
- Author(s): Chen, CK
- Benchaar, SA
- Phan, M
- Grintsevich, EE
- Loo, RRO
- Loo, JA
- Reisler, E
- et al.
Published Web Locationhttps://doi.org/10.1021/bi400715z
Cofilin is a member of the actin depolymerizing factor (ADF)/cofilin family of proteins. It plays a key role in actin dynamics by promoting disassembly and assembly of actin filaments. Upon its binding, cofilin has been shown to bridge two adjacent protomers in filamentous actin (F-actin) and promote the displacement and disordering of subdomain 2 of actin. Here, we present evidence for cofilin promoting a new structural change in the actin filament, as detected via a switch in cross-linking sites. Benzophenone-4-maleimide, which normally forms intramolecular cross-linking in F-actin, cross-links F-actin intermolecularly upon cofilin binding. We mapped the cross-linking sites and found that in the absence of cofilin intramolecular cross-linking occurred between residues Cys374 and Asp11. In contrast, cofilin shifts the cross-linking by this reagent to intermolecular, between residue Cys374, located within subdomain 1 of the upper protomer, and Met44, located in subdomain 2 of the lower protomer. The intermolecular cross-linking of F-actin slows the rate of cofilin dissociation from the filaments and decreases the effect of ionic strength on cofilin-actin binding. These results are consistent with a significant role of filament flexibility in cofilin-actin interactions. © 2013 American Chemical Society.
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