title: Expression, crystallization and X-ray diffraction analysis of a complex between B7-H6, a tumor cell ligand for the natural cytotoxicity receptor NKp30, and an inhibitory antibody.
abstract: Natural killer (NK) cells are essential components of the innate immune response to tumors and viral infections. In humans, the activating natural cytotoxicity receptor NKp30 plays a major role in NK cell-mediated tumor cell lysis. NKp30 recognizes the cell-surface protein B7-H6, which is expressed on tumor, but not healthy, cells. A mouse monoclonal antibody (17B1.3) against human B7-H6 has been developed (Kd = 0.2 µM) to investigate NKp30-mediated NK cell activation and to target tumors expressing B7-H6. Surprisingly, 17B1.3 blocks NK cell activation without interfering with the binding of B7-H6 to NKp30. Understanding the inhibitory mechanism of this antibody will require knowing the structure of 17B1.3 bound to B7-H6. The antigen-binding fragment (Fab) of 17B1.3 was expressed by in vitro folding from bacterial inclusion bodies. The extracellular domain of B7-H6 was produced by secretion from baculovirus-infected insect cells. Crystals of the Fab 17B1.3-B7-H6 complex grown by macro-seeding diffracted to 2.5 Å resolution and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 89.6, b = 138.0, c = 171.4 Å, α = β = γ = 90°. Comparison of the Fab 17B1.3-B7-H6 structure with the known NKp30-B7-H6 structure will elucidate the inhibitory mechanism of 17B1.3.
authors.affiliation: University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Xu
authors.affiliation: University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA.
authors.forename: Yili
authors.initials: Y
authors.lastname: Li
authors.affiliation: Innate Pharma S.A., 117 Avenue de Luminy, 13009 Marseille, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Gauthier
authors.affiliation: State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, Sichuan 610041, People's Republic of China.
authors.forename: Qianming
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Institut National de la Santé et de la Recherche Médical U1104, 13288 Marseille, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Vivier
authors.affiliation: University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, MD 20850, USA.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Mariuzza
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D060887:B7 Antigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016367:Baculoviridae / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D003602:Cytotoxicity, Immunologic; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D007694:Killer Cells, Natural / Q000737:chemistry / Q000276:immunology; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D055628:Natural Cytotoxicity Triggering Receptor 3 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D061987:Sf9 Cells; D018411:Spodoptera; D014407:Tumor Cells, Cultured
chemical_list: D057134:Antibodies, Neutralizing; D060887:B7 Antigens; D007140:Immunoglobulin Fab Fragments; D008024:Ligands; C542363:NCR3LG1 protein, human; D055628:Natural Cytotoxicity Triggering Receptor 3; D011994:Recombinant Proteins
keywords: B7-H6; NK cell; NKp30; antibody