title: Cloning, expression and preliminary X-ray analysis of the dihydroorotase from the hyperthermophilic eubacterium Aquifex aeolicus.
abstract: Dihydroorotase (DHOase) catalyzes the formation of dihydroorotate in the de novo pyrimidine biosynthetic pathway. The gene encoding the type I DHOase from the hyperthermophilic bacterium Aquifex aeolicus has been cloned in Escherichia coli with a polyhistidine affinity tag appended to the amino-terminal end and sequenced. The recombinant protein was expressed at high levels and could be purified readily in a single step by Ni(2+) affinity chromatography. Both native and selenomethionine-labeled proteins were crystallized using the hanging-drop vapor-diffusion technique. Screens of the purified protein identified several conditions that yielded crystals; however, the best crystals were obtained using 1 M Li(2)SO(4), 10 mM NiCl(2), 100 mM Tris acetate pH 8.5 as the precipitant. Well formed diamond-shaped crystals appeared within 1 d and continued to grow over several weeks to about 0.5 mm in the largest dimension. The crystals diffract to 1.7 A and belong to space group C2, with unit-cell parameters a = 119.8, b = 88.0, c = 55.2 A, beta = 99.0 degrees and a mosaic spread of 0.6 degrees. There is one DHOase monomer in the asymmetric unit.
authors.affiliation: Department of Biochemistry and Molecular Biology, Wayne State University School of Medicine, 540 East Canfield Street, Detroit, Michigan 48201, USA.
authors.forename: Cristina
authors.initials: C
authors.lastname: Purcarea
authors.forename: Phillip
authors.initials: P
authors.lastname: Martin
authors.forename: John F
authors.initials: JF
authors.lastname: Vickrey
authors.forename: Hedeel I
authors.initials: HI
authors.lastname: Guy
authors.forename: Brian F P
authors.initials: BF
authors.lastname: Edwards
authors.forename: David R
authors.initials: DR
authors.lastname: Evans
mesh_terms: D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D004080:Dihydroorotase / Q000737:chemistry* / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D011994:Recombinant Proteins; D004080:Dihydroorotase