title: Expression, purification and crystallization of Streptococcus dysgalactiae-derived mitogen.
abstract: Superantigens are bacterial or viral toxins with potent immunostimulatory properties. Streptococcus dysgalactiae-derived mitogen, a 25 kDa protein, is a recently discovered superantigen isolated from S. dysgalactiae culture supernatant. Sequence considerations suggest that it belongs to a new superantigen family distinct from other superantigens. The protein was expressed in Escherichia coli cells and purified to homogeneity. Crystals were grown at pH 4.2-4.4 in the presence of 18-20%(w/v) PEG 3350 and 0.4 M lithium nitrate. A complete data set to 2.4 A resolution was collected from a single crystal at liquid-nitrogen temperatures using synchrotron radiation. The crystals belong to space group P3/P3(1)/P3(2), with unit-cell parameters a = b = 52.7, c = 62.4 A, gamma = 120 degrees and one molecule in the crystallographic asymmetric unit.
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Turku 20521, Finland. tassos.papageorgiou@btk.fi
authors.forename: Anastassios C
authors.initials: AC
authors.lastname: Papageorgiou
authors.forename: Susanna
authors.initials: S
authors.lastname: Saarinen
authors.forename: Rosa
authors.initials: R
authors.lastname: Ramirez-Bartutis
authors.forename: Hidehito
authors.initials: H
authors.lastname: Kato
authors.forename: Takehiko
authors.initials: T
authors.lastname: Uchiyama
authors.forename: Teruo
authors.initials: T
authors.lastname: Kirikae
authors.forename: Toru
authors.initials: T
authors.lastname: Miyoshi-Akiyama
mesh_terms: D003460:Crystallization / Q000379:methods; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000378:metabolism; D008934:Mitogens / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D013291:Streptococcus / Q000737:chemistry*; D018089:Superantigens / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D008934:Mitogens; D018089:Superantigens