title: Contribution of arginine residues in the RP135 peptide derived from the V3 loop of gp120 to its interaction with the Fv fragment of the 0.5beta HIV-1 neutralizing antibody.
abstract: The construction, expression, and purification of an active Fv fragment of the 0.5beta monoclonal human immunodeficiency virus type 1 (HIV-1) neutralizing antibody is reported. The interaction between the Fv fragment and the RP135 peptide derived from the V3 loop of gp120 from HIV-1IIIB was studied by varying the salt concentration and by mutating arginine residues in the peptide. The mutations R4A, R8A and R11A (which correspond to residues 311, 315, and 318 in gp120 of HIV-1IIIB) reduce the binding free energy by 0.22 (+/- 0. 20), 4.32 (+/- 0.16), and 1.58 (+/- 0.17) kcal mol-1, respectively. The salt-dependent components of their contributions to binding are 0.02 (+/- 0.22), -0.55 (+/- 0.18), and -0.97 (+/- 0.19) kcal mol-1, respectively. The magnitudes of the mutational effects and the extent of shielding by 1 M NaCl suggest that Arg-8 is involved in a buried salt bridge in the peptide-Fv fragment complex, whereas Arg-11 is involved in a more solvent-exposed electrostatic interaction.
authors.affiliation: Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: G A
authors.initials: GA
authors.lastname: Faiman
authors.forename: R
authors.initials: R
authors.lastname: Levy
authors.forename: J
authors.initials: J
authors.lastname: Anglister
authors.forename: A
authors.initials: A
authors.lastname: Horovitz
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000936:Antigen-Antibody Complex / Q000737:chemistry; D001120:Arginine / Q000737:chemistry; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015483:HIV Antibodies / Q000737:chemistry*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D015497:HIV-1 / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009500:Neutralization Tests; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D009838:Oligodeoxyribonucleotides; D010446:Peptide Fragments; D001120:Arginine