title: Evidence for an actin binding helix in gelsolin segment 2; have homologous sequences in segments 1 and 2 of gelsolin evolved to divergent actin binding functions?
abstract: Gelsolin is built up of six homologous segments that perform different functions on actin. Segments 1 and 2, which are suggested to be highly similar in their overall folds, bind monomeric and filamentous actin respectively. A long alpha-helix in segment 1 forms the major contact site of this segment with actin. We show that sequence 197-226 of segment 2, equivalent to the region around the actin binding helix in segment 1, contains F-actin binding activity. Consequently, positionally similar parts of segment 1 and 2 are implicated in the actin contact and solvent exposed residues in these parts must have evolved differentially to meet their different actin binding properties.
authors.affiliation: Flanders Interuniversity Institute for Biotechnology, Department of Biochemistry, Faculty of Medicine, Universiteit Gent, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Van Troys
authors.forename: D
authors.initials: D
authors.lastname: Dewitte
authors.forename: M
authors.initials: M
authors.lastname: Goethals
authors.forename: J
authors.initials: J
authors.lastname: Vandekerckhove
authors.forename: C
authors.initials: C
authors.lastname: Ampe
mesh_terms: D000199:Actins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D001665:Binding Sites; D002942:Circular Dichroism; D019143:Evolution, Molecular; D018260:Gelsolin / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D000199:Actins; D000906:Antibodies; D018260:Gelsolin; D010446:Peptide Fragments