title: Cofilin-induced changes in F-actin detected via cross-linking with benzophenone-4-maleimide.
abstract: 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.
authors.affiliation: Department of Chemistry and Biochemistry, Molecular Biology Institute and Biological Chemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Christine K
authors.initials: CK
authors.lastname: Chen
authors.forename: Sabrina A
authors.initials: SA
authors.lastname: Benchaar
authors.forename: Mai
authors.initials: M
authors.lastname: Phan
authors.forename: Elena E
authors.initials: EE
authors.lastname: Grintsevich
authors.forename: Rachel R Ogorzalek
authors.initials: RR
authors.lastname: Loo
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Loo
authors.forename: Emil
authors.initials: E
authors.lastname: Reisler
mesh_terms: D051339:Actin Depolymerizing Factors / Q000737:chemistry* / Q000378:metabolism; D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D001577:Benzophenones / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003432:Cross-Linking Reagents / Q000737:chemistry* / Q000378:metabolism; D008301:Maleimides / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D011817:Rabbits
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D001577:Benzophenones; D003432:Cross-Linking Reagents; D008301:Maleimides; C046109:benzophenone-4-maleimide