title: Structure of a mutant β toxin from Staphylococcus aureus reveals domain swapping and conformational flexibility.
abstract: The 3.35 Å resolution crystal structure of a mutant form of the staphylococcal sphingomyelinase β toxin in which a conserved hydrophobic β-hairpin has been deleted is reported. It is shown that this mutation induces domain swapping of a C-terminal β-strand, leading to the formation of dimers linked by a conformationally flexible hinge region. Eight dimers are seen in the asymmetric unit, exhibiting a broad spectrum of conformations trapped in place by intermolecular contacts within the crystal lattice. Furthermore, the 16 monomers within each asymmetric unit exhibit a remarkable heterogeneity in thermal factors, which can be accounted for by the varying degrees to which each monomer interacts with other molecules in the crystal. This structure provides a unique example of the challenges associated with crystallographic study of flexible proteins.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Kruse
authors.forename: Medora J
authors.initials: MJ
authors.lastname: Huseby
authors.forename: Ke
authors.initials: K
authors.lastname: Shi
authors.forename: Jeff
authors.initials: J
authors.lastname: Digre
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Ohlendorf
authors.forename: Cathleen A
authors.initials: CA
authors.lastname: Earhart
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000235:genetics
chemical_list: D001427:Bacterial Toxins