Crystal structure of the antigen-binding fragment of a monoclonal antibody specific for the multidrug-resistance-linked ABC transporter human P-glycoprotein

Acta Crystallogr F Struct Biol Commun. 2016 Aug;72(Pt 8):636-41. doi: 10.1107/S2053230X16009778. Epub 2016 Jul 27.

Abstract

P-glycoprotein (P-gp) is a polyspecific ATP-dependent transporter linked to multidrug resistance in cancers that plays important roles in the pharmacokinetics of a large number of drugs. The drug-resistance phenotype of P-gp can be modulated by the monoclonal antibody UIC2, which specifically recognizes human P-gp in a conformation-dependent manner. Here, the purification, sequence determination and high-resolution structure of the Fab fragment of UIC2 (UIC2/Fab) are reported. Purified UIC2/Fab binds human P-gp with a 1:1 stoichiometry. Crystals of UIC2/Fab are triclinic (space group P1), with unit-cell parameters a = 40.67, b = 44.91, c = 58.09 Å, α = 97.62, β = 99.10, γ = 94.09°, and diffracted X-rays to 1.6 Å resolution. The structure was determined by molecular replacement and refined to 1.65 Å resolution. The asymmetric unit contains one molecule of UIC2/Fab, which exhibits a positively charged antigen-binding surface, suggesting that it might recognize an oppositely charged extracellular epitope of P-gp.

Keywords: UIC2/Fab; human ABC-dependent transporter P-glycoprotein; monoclonal antibodies; multidrug resistance.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / chemistry*
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Amino Acid Motifs
  • Animals
  • Antibodies, Monoclonal / biosynthesis
  • Antibodies, Monoclonal / chemistry*
  • Antibodies, Monoclonal / isolation & purification
  • Antigens / chemistry*
  • Antigens / metabolism
  • Binding Sites
  • Cloning, Molecular
  • Crystallography, X-Ray
  • Gene Expression
  • Humans
  • Hybridomas / chemistry
  • Immunoglobulin Fab Fragments / biosynthesis
  • Immunoglobulin Fab Fragments / chemistry*
  • Immunoglobulin Fab Fragments / isolation & purification
  • Mice
  • Mice, Inbred BALB C
  • Models, Molecular
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Structure, Secondary
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Antibodies, Monoclonal
  • Antigens
  • Immunoglobulin Fab Fragments
  • Recombinant Proteins