title: Atomic basis for the species-specific inhibition of αV integrins by monoclonal antibody 17E6 is revealed by the crystal structure of αVβ3 ectodomain-17E6 Fab complex.
abstract: The function-blocking, non-RGD-containing, and primate-specific mouse monoclonal antibody 17E6 binds the αV subfamily of integrins. 17E6 is currently in phase II clinical trials for treating cancer. To elucidate the structural basis of recognition and the molecular mechanism of inhibition, we crystallized αVβ3 ectodomain in complex with the Fab fragment of 17E6. Protein crystals grew in presence of the activating cation Mn(2+). The integrin in the complex and in solution assumed the genuflected conformation. 17E6 Fab bound exclusively to the Propeller domain of the αV subunit. At the core of αV-Fab interface were interactions involving Propeller residues Lys-203 and Gln-145, with the latter accounting for primate specificity. The Propeller residue Asp-150, which normally coordinates Arg of the ligand Arg-Gly-Asp motif, formed contacts with Arg-54 of the Fab that were expected to reduce soluble FN10 binding to cellular αVβ3 complexed with 17E6. This was confirmed in direct binding studies, suggesting that 17E6 is an allosteric inhibitor of αV integrins.
authors.affiliation: From the Structural Biology Program and.
authors.forename: Bhuvaneshwari
authors.initials: B
authors.lastname: Mahalingam
authors.affiliation: From the Structural Biology Program and.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Van Agthoven
authors.affiliation: From the Structural Biology Program and.
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Xiong
authors.affiliation: the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Alonso
authors.affiliation: From the Structural Biology Program and.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Adair
authors.affiliation: the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129.
authors.forename: Xianliang
authors.initials: X
authors.lastname: Rui
authors.affiliation: the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Anand
authors.affiliation: the Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720.
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Mehrbod
authors.affiliation: the Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, California 94720.
authors.forename: Mohammad R K
authors.initials: MR
authors.lastname: Mofrad
authors.affiliation: Merck KGaA and Discovery Technologies, Molecular Pharmacology, and.
authors.forename: Christa
authors.initials: C
authors.lastname: Burger
authors.affiliation: Merck KGaA and Therapeutic Innovation Platform, Oncology, Darmstadt 64271, Germany.
authors.forename: Simon L
authors.initials: SL
authors.lastname: Goodman
authors.affiliation: From the Structural Biology Program and the Leukocyte Biology and Inflammation Program, Departments of Medicine and Developmental & Regenerative Biology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, aarnaout1@mgh.harvard.edu.
authors.forename: M Amin
authors.initials: MA
authors.lastname: Arnaout
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology*; D002460:Cell Line; D018360:Crystallography, X-Ray; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D039564:Integrin alphaV / Q000737:chemistry* / Q000276:immunology*; D039302:Integrin alphaVbeta3 / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011323:Primates; D017434:Protein Structure, Tertiary; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D039564:Integrin alphaV; D039302:Integrin alphaVbeta3; D008345:Manganese
keywords: Cancer Therapy; Cell Adhesion; Cell Surface Receptor; Crystal Structure; Extracellular Matrix Proteins; Fibronectin; Integrins