Cofilin-Induced Changes in F-Actin Detected via Cross-Linking with Benzophenone-4-maleimide

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• 作者：Christine K. Chen ; Sabrina A. Benchaar ; Mai Phan ; Elena E. Grintsevich ; Rachel R. Ogorzalek Loo ; Joseph A. Loo ; Emil Reisler
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：August 13, 2013
• 年：2013
• 卷：52
• 期：32
• 页码：5503-5509
• 全文大小：330K
• 年卷期：v.52,no.32(August 13, 2013)
• ISSN：1520-4995

文摘

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鈥揳ctin binding. These results are consistent with a significant role of filament flexibility in cofilin鈥揳ctin interactions.