title: Identification of functional residues on Caenorhabditis elegans actin-interacting protein 1 (UNC-78) for disassembly of actin depolymerizing factor/cofilin-bound actin filaments.
abstract: Actin-interacting protein 1 (AIP1) is a WD40 repeat protein that enhances actin filament disassembly in the presence of actin-depolymerizing factor (ADF)/cofilin. AIP1 also caps the barbed end of ADF/cofilin-bound actin filament. However, the mechanism by which AIP1 interacts with ADF/cofilin and actin is not clearly understood. We determined the crystal structure of Caenorhabditis elegans AIP1 (UNC-78), which revealed 14 WD40 modules arranged in two seven-bladed beta-propeller domains. The structure allowed for the mapping of conserved surface residues, and mutagenesis studies identified five residues that affected the ADF/cofilin-dependent actin filament disassembly activity. Mutations of these residues, which reside in blades 3 and 4 in the N-terminal propeller domain, had significant effects on the disassembly activity but did not alter the barbed end capping activity. These data support a model in which this conserved surface of AIP1 plays a direct role in enhancing fragmentation/depolymerization of ADF/cofilin-bound actin filaments but not in barbed end capping.
authors.affiliation: Department of Pathology, Emory University, Atlanta, Georgia 30322, USA.
authors.forename: Kurato
authors.initials: K
authors.lastname: Mohri
authors.forename: Sergeui
authors.initials: S
authors.lastname: Vorobiev
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Fedorov
authors.forename: Steven C
authors.initials: SC
authors.lastname: Almo
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Ono
mesh_terms: D051339:Actin Depolymerizing Factors; D000199:Actins / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000235:genetics; D051345:Destrin; D066298:In Vitro Techniques; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D051339:Actin Depolymerizing Factors; D000199:Actins; D029742:Caenorhabditis elegans Proteins; D017931:DNA Primers; D051345:Destrin; D008840:Microfilament Proteins; D011993:Recombinant Fusion Proteins; C423987:unc-78 protein, C elegans