title: Crystallization and preliminary X-ray diffraction analysis of a functional form of pneumolysin, a virulence factor from Streptococcus pneumoniae.
abstract: Pneumolysin is a virulence factor from Streptococcus pneumoniae, a Gram-positive bacterial pathogen which causes human infections with a severe impact on mortality and morbidity worldwide. The enzyme belongs to a group of cholesterol-dependent cytolysins and interacts with its cholesterol receptor on target cells, leading to pneumolysin insertion into target-cell membranes and subsequently to pore formation and cell lysis. Pneumolysin has been overexpressed, purified and crystallized for X-ray diffraction studies. Crystals have been obtained in the presence of cholesterol in an effort to produce a three-dimensional structure of pneumolysin in its fully functional form with the enzyme bound to its activator. This is the first report of the crystallization of a cholesterol-dependent cytolysin in the presence of bound cholesterol. The vapor-diffusion method using ammonium sulfate as a precipitation agent was used to grow crystals in the presence of n-octyl-beta-D-glucopyranoside and phosphatidylcholine. Crystals of this 53 kDa molecule complexed with cholesterol diffracted X-rays to 3.3 A. The crystal unit cell has parameters a = b = 191.45, c = 66.16 A, alpha = beta = 90.0, gamma = 120 degrees and belongs to the trigonal space group P3. The determination of the three-dimensional structure of this pneumococcal cytolysin is in progress.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, AL 35294, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Kelly
authors.forename: M J
authors.initials: MJ
authors.lastname: Jedrzejas
mesh_terms: D001426:Bacterial Proteins; D003460:Crystallization; D018360:Crystallography, X-Ray; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D013301:Streptolysins / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae