title: The crystal structure of recombinant human neutrophil-activating peptide-2 (M6L) at 1.9-A resolution.
abstract: Neutrophil-activating peptide-2 (NAP-2) is a 70-residue carboxyl-terminal fragment of platelet basic protein, which is found in the alpha-granules of human platelets. NAP-2, which belongs to the CXC family of chemokines that includes interleukin-8 and platelet factor 4, binds to the interleukin-8 type II receptor and induces a rise in cytosolic calcium, chemotaxis of neutrophils, and exocytosis. Crystals of recombinant NAP-2 in which the single methionine at position 6 was replaced by leucine to facilitate expression belong to space group P1 (unit cell parameters a = 40.8, b = 43.8, and c = 44.7 A and alpha = 98.4 degrees, beta = 120.3 degrees, and gamma = 92.8 degrees), with 4 molecules of NAP-2 (Mr = 7600) in the asymmetric unit. The molecular replacement solution calculated with bovine platelet factor 4 as the starting model was refined using rigid body refinement, manual fitting in solvent-leveled electron density maps, simulated annealing, and restrained least squares to an R-factor of 0.188 for 2 sigma data between 7.0- and 1.9-A resolution. The final refined crystal structure includes 265 solvent molecules. The overall tertiary structure, which is similar to that of platelet factor 4 and interleukin-8, includes an extended amino-terminal loop, three strands of antiparallel beta-sheet arranged in a Greek key fold, and one alpha-helix at the carboxyl terminus. The Glu-Leu-Arg sequence that is critical for receptor binding is fully defined by electron density and exhibits multiple conformations.
authors.affiliation: Department of Biochemistry, Wayne State University, Detroit, Michigan 48201, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Malkowski
authors.forename: J Y
authors.initials: JY
authors.lastname: Wu
authors.forename: J B
authors.initials: JB
authors.lastname: Lazar
authors.forename: P H
authors.initials: PH
authors.lastname: Johnson
authors.forename: B F
authors.initials: BF
authors.lastname: Edwards
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli; D006801:Humans; D006860:Hydrogen Bonding; D016209:Interleukin-8 / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000378:metabolism; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification; D010978:Platelet Factor 4 / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D001620:beta-Thromboglobulin
chemical_list: D016209:Interleukin-8; C061615:PPBP protein, human; D010455:Peptides; D011994:Recombinant Proteins; D001620:beta-Thromboglobulin; D010978:Platelet Factor 4; C009862:connective tissue-activating peptide