title: Improvement of the quality of lumazine synthase crystals by protein engineering.
abstract: Icosahedral macromolecules have a wide spectrum of potential nanotechnological applications, the success of which relies on the level of accuracy at which the molecular structure is known. Lumazine synthase from Bacillus subtilis forms a 150 A icosahedral capsid consisting of 60 subunits and crystallizes in space group P6(3)22 or C2. However, the quality of these crystals is poor and structural information is only available at 2.4 A resolution. As classical strategies for growing better diffracting crystals have so far failed, protein engineering has been employed in order to improve the overexpression and purification of the molecule as well as to obtain new crystal forms. Two cysteines were replaced to bypass misfolding problems and a charged surface residue was replaced to force different molecular packings. The mutant protein crystallizes in space group R3, with unit-cell parameters a = b = 313.02, c = 365.77 A, alpha = beta = 90.0, gamma = 120 degrees , and diffracts to 1.6 A resolution.
authors.affiliation: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Lidia
authors.initials: L
authors.lastname: Rodríguez-Fernández
authors.forename: F Javier
authors.initials: FJ
authors.lastname: López-Jaramillo
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
authors.forename: Markus
authors.initials: M
authors.lastname: Fischer
authors.forename: Sevil
authors.initials: S
authors.lastname: Weinkauf
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000592:standards; D003460:Crystallization / Q000379:methods / Q000592:standards; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000592:standards*; D016297:Mutagenesis, Site-Directed / Q000379:methods / Q000592:standards; D015202:Protein Engineering / Q000379:methods / Q000592:standards*; D012258:Riboflavin Synthase / Q000737:chemistry / Q000235:genetics / Q000592:standards
chemical_list: D001426:Bacterial Proteins; D009097:Multienzyme Complexes; C044822:6,7-dimethyl-8-ribityllumazine synthase; D012258:Riboflavin Synthase