title: Understanding the polymorphic behaviour of a mutant of the α-spectrin SH3 domain by means of two 1.1 Å resolution structures.
abstract: SH3 domains are small protein modules that mediate the assembly of specific protein complexes, typically via binding to proline-rich sequences in their respective binding partners. Most of the α-spectrin SH3-domain (Spc-SH3) structures determined to date using X-ray diffraction have been solved from crystals belonging to the orthorhombic space group P2(1)2(1)2(1) with a needle-like morphology. All of these orthorhombic crystals exhibited a rapid growth rate. In addition to this crystal form, the R21D mutant of Spc-SH3 crystallizes in a new crystal form in the presence of sodium formate at pH values higher than 6. This new crystal form grows at a slower rate and belongs to the hexagonal space group P6(5)22, with unit-cell parameters a = b = 42.9, c = 127.5 Å. When both polymorphs of the R21D mutant of Spc-SH3 are simultaneously present into the same solution, it has been observed that the hexagonal crystals grow at the expense of the orthorhombic crystals. The availability of 1.1 Å resolution structures for both crystal forms allows the identification of key features that could account for the observed polymorphic behaviour.
authors.affiliation: Departamento de Química Física, Bioquímica y Química Inorgánica, Universidad de Almería, Spain. acamara@ual.es
authors.forename: Ana
authors.initials: A
authors.lastname: Cámara-Artigas
authors.forename: Jose Antonio
authors.initials: JA
authors.lastname: Gavira
authors.forename: Salvador
authors.initials: S
authors.lastname: Casares
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Garcia-Ruiz
authors.forename: Francisco
authors.initials: F
authors.lastname: Conejero-Lara
authors.forename: James P
authors.initials: JP
authors.lastname: Allen
authors.forename: Jose C
authors.initials: JC
authors.lastname: Martinez
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009154:Mutation; D011110:Polymorphism, Genetic; D013049:Spectrin / Q000737:chemistry* / Q000235:genetics; D055672:Static Electricity; D018909:src Homology Domains
chemical_list: D013049:Spectrin