title: Activation in isolation: exposure of the actin-binding site in the C-terminal half of gelsolin does not require actin.
abstract: Gelsolin requires activation to carry out its severing and capping activities on F-actin. Here, we present the structure of the isolated C-terminal half of gelsolin (G4-G6) at 2.0 A resolution in the presence of Ca(2+) ions. This structure completes a triptych of the states of activation of G4-G6 that illuminates its role in the function of gelsolin. Activated G4-G6 displays an open conformation, with the actin-binding site on G4 fully exposed and all three type-2 Ca(2+) sites occupied. Neither actin nor the type-l Ca(2+), which normally is sandwiched between actin and G4, is required to achieve this conformation.
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, 751 23 Uppsala, Sweden.
authors.forename: Kartik
authors.initials: K
authors.lastname: Narayan
authors.forename: Sakesit
authors.initials: S
authors.lastname: Chumnarnsilpa
authors.forename: Han
authors.initials: H
authors.lastname: Choe
authors.forename: Edward
authors.initials: E
authors.lastname: Irobi
authors.forename: Dunja
authors.initials: D
authors.lastname: Urosev
authors.forename: Uno
authors.initials: U
authors.lastname: Lindberg
authors.forename: Clarence E
authors.initials: CE
authors.lastname: Schutt
authors.forename: Leslie D
authors.initials: LD
authors.lastname: Burtnick
authors.forename: Robert C
authors.initials: RC
authors.lastname: Robinson
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D018360:Crystallography, X-Ray; D018260:Gelsolin / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011817:Rabbits
chemical_list: D000199:Actins; D018260:Gelsolin; D002118:Calcium