title: Deletion of the V1/V2 region does not increase the accessibility of the V3 region of recombinant gp125.
abstract: Previous analyses of HIV-1 surface glycoprotein indicate that both the V1/V2 region and the interaction of gp120 with CD4 influence the accessibility of the V3 region on gp120. In this study we investigated the accessibility of the V3 region of HIV-2 recombinant gp125 proteins using V3-specific mAbs (7C8 and 3C4) and analyzed the binding kinetics of soluble CD4 (sCD4) to recombinant HIV-1 gp120 and HIV-2 gp125 proteins by surface plasmon resonance (SPR) analysis. Our results indicated that 7C8 recognized monomers of gp125 and gp125Delta v1v2, (lacking the V1/V2 region) while 3C4 was sensitive to the conformation of gp125, recognizing only oligomers of gp125Delta v1v2. Furthermore, SPR analysis of 7C8 binding to gp125 demonstrated that the deletion of the V1/V2 region did not increase the accessibility of the V3 region in gp125Delta v1v2. Comparative SPR analyses of sCD4 binding HIV recombinant surface glycoproteins revealed a lower affinity of sCD4 to gp125 as compared to gp120. Moreover, the analyses suggest that conformational changes only occur in HIV-1 gp120 upon interaction with CD4. We hypothesize that the V3 region is accessible in HIV-2 gp125 and thus may not require interaction with CD4 to induce conformational reorientation of the V1/V2 region.
authors.affiliation: Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden. Samer@strubi.ox.ac.uk
authors.forename: Samer
authors.initials: S
authors.lastname: Sourial
authors.forename: Charlotta
authors.initials: C
authors.lastname: Nilsson
authors.forename: Anette
authors.initials: A
authors.lastname: Wärnmark
authors.forename: Adnane
authors.initials: A
authors.lastname: Achour
authors.forename: Robert A
authors.initials: RA
authors.lastname: Harris
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015153:Blotting, Western; D015704:CD4 Antigens / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D015686:Gene Products, env / Q000276:immunology* / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000276:immunology* / Q000378:metabolism; D015497:HIV-1 / Q000276:immunology; D015498:HIV-2 / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology* / Q000378:metabolism; D011487:Protein Conformation; D011498:Protein Precursors / Q000276:immunology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000276:immunology; D016415:Sequence Alignment; D020349:Surface Plasmon Resonance; D054299:env Gene Products, Human Immunodeficiency Virus
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D011498:Protein Precursors; D011994:Recombinant Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; C066316:gp125 envelope protein, Human immunodeficiency virus 2