title: Coronin Enhances Actin Filament Severing by Recruiting Cofilin to Filament Sides and Altering F-Actin Conformation.
abstract: High rates of actin filament turnover are essential for many biological processes and require the activities of multiple actin-binding proteins working in concert. The mechanistic role of the actin filament severing protein cofilin is now firmly established; however, the contributions of other conserved disassembly-promoting factors including coronin have remained more obscure. Here, we have investigated the mechanism by which yeast coronin (Crn1) enhances F-actin turnover. Using multi-color total internal reflection fluorescence microscopy, we show that Crn1 enhances Cof1-mediated severing by accelerating Cof1 binding to actin filament sides. Further, using biochemical assays to interrogate F-actin conformation, we show that Crn1 alters longitudinal and lateral actin-actin contacts and restricts opening of the nucleotide-binding cleft in actin subunits. Moreover, Crn1 and Cof1 show opposite structural effects on F-actin yet synergize in promoting release of phalloidin from filaments, suggesting that Crn1/Cof1 co-decoration may increase local discontinuities in filament topology to enhance severing.
authors: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
authors: Mouna A
authors: MA
authors: Mikati
authors: Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA.
authors: Dennis
authors: D
authors: Breitsprecher
authors: Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA.
authors: Silvia
authors: S
authors: Jansen
authors: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA. Electronic address: reisler@mbi.ucla.edu.
authors: Emil
authors: E
authors: Reisler
authors: Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA. Electronic address: goode@brandeis.edu.
authors: Bruce L
authors: BL
authors: Goode
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D000199:Actins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D001665:Binding Sites; D051338:Cofilin 1 / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; C495813:COF1 protein, S cerevisiae; D051338:Cofilin 1; D008840:Microfilament Proteins; D029701:Saccharomyces cerevisiae Proteins; C072061:coronin proteins
keywords: actin; cofilin; coronin; cross-linking; severing