Three-dimensional structure and antigenicity of transmembrane-protein peptides of the human immunodeficiency virus type 1

ABSTRACT T-20 is a synthetic peptide that potently inhibits replication of human immunodeficiency virus type 1 by interfering with the transition of the transmembrane protein, gp41, to a fusion active state following interactions of the surface glycoprotein, gp120, with CD4 and coreceptor molecules displayed on the target cell surface. Although T-20 is postulated to interact with an N-terminal heptad repeat within gp41 in a trans-dominant manner, we show here that sensitivity to T-20 is strongly influenced by coreceptor specificity. When 14 T-20-naive primary isolates were analyzed for sensitivity to T-20, the mean 50% inhibitory concentration (IC50) for isolates that utilize CCR5 for entry (R5 viruses) was 0.8 log10 higher than the mean IC50 for CXCR4 (X4) isolates (P = 0.0055). Using NL4.3-based envelope chimeras that contain combinations of envelope sequences derived from R5 and X4 viruses, we found that determinants of coreceptor specificity contained within the gp120 V3 loop modulate this sensitivity to T-20. The IC50 for all chimeric envelope viruses containing R5 V3 sequences was 0.6 to 0.8 log10higher than that for viruses containing X4 V3 sequences. In addition, we confirmed that the N-terminal heptad repeat of gp41 determines the baseline sensitivity to T-20 and that the IC50 for viruses containing GIV at amino acid residues 36 to 38 was 1.0 log10 lower than the IC50 for viruses containing a G-to-D substitution. The results of this study show that gp120-coreceptor interactions and the gp41 N-terminal heptad repeat independently contribute to sensitivity to T-20. These results have important implications for the therapeutic uses of T-20 as well as for unraveling the complex mechanisms of virus fusion and entry.

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Effect of amino acid substitutions on calmodulin binding and cytolytic properties of the LLP-1 peptide segment of human immunodeficiency virus type 1 transmembrane protein.

Journal of Virology ◽

10.1128/jvi.69.8.5199-5202.1995 ◽

1995 ◽

Vol 69 (8) ◽

pp. 5199-5202 ◽

Cited By ~ 35

Author(s):

S B Tencza ◽

M A Miller ◽

K Islam ◽

T A Mietzner ◽

R C Montelaro

Keyword(s):

Human Immunodeficiency Virus ◽

Amino Acid ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Transmembrane Protein ◽

Amino Acid Substitutions ◽

Calmodulin Binding ◽

Immunodeficiency Virus

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Molecular Features of the Broadly Neutralizing Immunoglobulin G1 b12 Required for Recognition of Human Immunodeficiency Virus Type 1 gp120

Journal of Virology ◽

10.1128/jvi.77.10.5863-5876.2003 ◽

2003 ◽

Vol 77 (10) ◽

pp. 5863-5876 ◽

Cited By ~ 78

Author(s):

Michael B. Zwick ◽

Paul W. H. I. Parren ◽

Erica O. Saphire ◽

Sarah Church ◽

Meng Wang ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Binding Site ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Dimensional Structure ◽

Side Chains ◽

Molecular Features ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT IgG1 b12 is a broadly neutralizing antibody against human immunodeficiency virus type 1 (HIV-1). The epitope recognized by b12 overlaps the CD4 receptor-binding site (CD4bs) on gp120 and has been a target for vaccine design. Determination of the three-dimensional structure of immunoglobulin G1 (IgG1) b12 allowed modeling of the b12-gp120 interaction in which the protruding third complementarity-determining region (CDR) of the heavy chain (H3) was crucial for antibody binding. In the present study, extensive mutational analysis of the antigen-binding site of Fab b12 was carried out to investigate the validity of the model and to identify residues important for gp120 recognition and, by inference, key to the anti-HIV-1 activity of IgG1 b12. In all, 50 mutations were tested: 40 in H3, 4 each in H2 and L1, and 2 in L3. The results suggest that the interaction of gp120 with H3 of b12 is crucially dependent not only on a Trp residue at the apex of the H3 loop but also on a number of residues at the base of the loop. The arrangement of these residues, including aromatic side chains and side chains that hydrogen bond across the base of the loop, may rigidify H3 for penetration of the recessed CD4-binding cavity. The results further emphasize the importance to gp120 binding of a Tyr residue at the apex of the H2 loop that forms a second finger-like structure and a number of Arg residues in L1 that form a positively charged, shelf-like structure. In general, the data are consistent with the b12-gp120 interaction model previously proposed. At the gene level, somatic mutation is seen to be crucial for the generation of many of the structural features described. The Fab b12 mutants were also tested against the b12 epitope-mimic peptide B2.1, and the reactivity profile had many similarities but also significant differences from that observed for gp120. The paratope map of b12 may facilitate the design of molecules that are able to elicit b12-like activities.

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Peptides Corresponding to the Heptad Repeat Motifs in the Transmembrane Protein (gp41) of Human Immunodeficiency Virus Type 1 Elicit Antibodies to Receptor-Activated Conformations of the Envelope Glycoprotein

Journal of Virology ◽

10.1128/jvi.75.18.8859-8863.2001 ◽

2001 ◽

Vol 75 (18) ◽

pp. 8859-8863 ◽

Cited By ~ 42

Author(s):

Eve de Rosny ◽

Russell Vassell ◽

Paul T. Wingfield ◽

Carl T. Wild ◽

Carol D. Weiss

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Transmembrane Protein ◽

Heptad Repeat ◽

Immunodeficiency Virus ◽

Protein Gp41 ◽

Hiv 1 ◽

Bundle Structure

ABSTRACT Two heptad repeat regions in the ectodomain of the human immunodeficiency virus type 1 (HIV-1) transmembrane subunit (gp41) self-assemble into a six-helix bundle structure that is critical for virus entry. Immunizations with peptides corresponding to these regions generated antibodies specific to the receptor-activated conformations of gp41.

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