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Title: Crystal Structures of HIV-1 gp120 Envelope Glycoprotein in Complex with NBD Analogues That Target the CD4-Binding Site

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2];  [2];  [2]
  1. L.F. Kimball
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NIHNIAID
OSTI Identifier:
1251233
Resource Type:
Journal Article
Resource Relation:
Journal Name: PLoS ONE; Journal Volume: 9; Journal Issue: (1) ; 01, 2014
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Kwon, Young Do, LaLonde, Judith M., Yang, Yongping, Elban, Mark A., Sugawara, Akihiro, Courter, Joel R., Jones, David M., Smith, III, Amos B., Debnath, Asim K., Kwong, Peter D., UPENN), Bryn Mawr), and NIAID). Crystal Structures of HIV-1 gp120 Envelope Glycoprotein in Complex with NBD Analogues That Target the CD4-Binding Site. United States: N. p., 2016. Web. doi:10.1371/journal.pone.0085940.
Kwon, Young Do, LaLonde, Judith M., Yang, Yongping, Elban, Mark A., Sugawara, Akihiro, Courter, Joel R., Jones, David M., Smith, III, Amos B., Debnath, Asim K., Kwong, Peter D., UPENN), Bryn Mawr), & NIAID). Crystal Structures of HIV-1 gp120 Envelope Glycoprotein in Complex with NBD Analogues That Target the CD4-Binding Site. United States. doi:10.1371/journal.pone.0085940.
Kwon, Young Do, LaLonde, Judith M., Yang, Yongping, Elban, Mark A., Sugawara, Akihiro, Courter, Joel R., Jones, David M., Smith, III, Amos B., Debnath, Asim K., Kwong, Peter D., UPENN), Bryn Mawr), and NIAID). 2016. "Crystal Structures of HIV-1 gp120 Envelope Glycoprotein in Complex with NBD Analogues That Target the CD4-Binding Site". United States. doi:10.1371/journal.pone.0085940.
@article{osti_1251233,
title = {Crystal Structures of HIV-1 gp120 Envelope Glycoprotein in Complex with NBD Analogues That Target the CD4-Binding Site},
author = {Kwon, Young Do and LaLonde, Judith M. and Yang, Yongping and Elban, Mark A. and Sugawara, Akihiro and Courter, Joel R. and Jones, David M. and Smith, III, Amos B. and Debnath, Asim K. and Kwong, Peter D. and UPENN) and Bryn Mawr) and NIAID)},
abstractNote = {},
doi = {10.1371/journal.pone.0085940},
journal = {PLoS ONE},
number = (1) ; 01, 2014,
volume = 9,
place = {United States},
year = 2016,
month = 7
}
  • Highlights: Black-Right-Pointing-Pointer Some recombinant HIV-1 gp120s do not preserve their conformations on gp140s. Black-Right-Pointing-Pointer We hypothesize that CD4i antibodies could induce conformational changes in gp120. Black-Right-Pointing-Pointer CD4i antibodies enhance binding of CD4 and CD4bs antibodies to gp120. Black-Right-Pointing-Pointer CD4i antibody-gp120 fusion proteins could have potential as vaccine immunogens. -- Abstract: Development of successful AIDS vaccine immunogens continues to be a major challenge. One of the mechanisms by which HIV-1 evades antibody-mediated neutralizing responses is the remarkable conformational flexibility of its envelope glycoprotein (Env) gp120. Some recombinant gp120s do not preserve their conformations on gp140s and functional viral spikes, and exhibitmore » decreased recognition by CD4 and neutralizing antibodies. CD4 binding induces conformational changes in gp120 leading to exposure of the coreceptor-binding site (CoRbs). In this study, we test our hypothesis that CD4-induced (CD4i) antibodies, which target the CoRbs, could also induce conformational changes in gp120 leading to better exposed conserved neutralizing antibody epitopes including the CD4-binding site (CD4bs). We found that a mixture of CD4i antibodies with gp120 only weakly enhanced CD4 binding. However, such interactions in single-chain fusion proteins resulted in gp120 conformations which bound to CD4 and CD4bs antibodies better than the original or mutagenically stabilized gp120s. Moreover, the two molecules in the fusion proteins synergized with each other in neutralizing HIV-1. Therefore, fusion proteins of gp120 with CD4i antibodies could have potential as components of HIV-1 vaccines and inhibitors of HIV-1 entry, and could be used as reagents to explore the conformational flexibility of gp120 and mechanisms of entry and immune evasion.« less
  • Staphylococcus aureus is a significant human pathogen. Among its large repertoire of secreted toxins is a group of staphylococcal superantigen-like proteins (SSLs). These are homologous to superantigens but do not have the same activity. SSL5 is shown here to bind to human granulocytes and to the cell surface receptors for human IgA (Fc alphaRI) and P-selectin [P-selectin glycoprotein ligand-1 (PSGL-1)] in a sialic acid (Sia)-dependent manner. Co-crystallization of SSL5 with the tetrasaccharide sialyl Lewis X (sLe(X)), a key determinant of PSGL-1 binding to P-selectin, led to crystal structures of the SSL5-sLe(X) complex at resolutions of 1.65 and 2.75 A formore » crystals at two pH values. In both structures, sLe(X) bound to a specific site on the surface of the C-terminal domain of SSL5 in a conformation identical with that bound by P-selectin. Conservation of the key carbohydrate binding residues indicates that this ability to bind human glycans is shared by a substantial subgroup of the SSLs, including SSL2, SSL3, SSL4, SSL5, SSL6, and SSL11. This indicates that the ability to target human glycans is an important property of this group of toxins. Structural comparisons also showed that the Sia binding site in SSL5 contains a substructure that is shared by other Sia binding proteins from bacteria as well as viruses and represents a common binding motif.« less
  • The caprine arthritis-encephalitis (CAEV) and ovine maedi-visna (MVV) viruses are resistant to antibody neutralization, a feature shared with all other lentiviruses. Whether the CAEV gp135 receptor binding site(s) (RBS) in the functional surface envelope glycoprotein (Env) is protected from antibody binding, allowing the virus to resist neutralization, is not known. Two CAEV gp135 regions were identified by extrapolating a gp135 structural model that could affect binding of antibodies to the RBS: the V1 region and a short sequence analogous in position to the human immunodeficiency virus type 1 gp120 loop B postulated to be located between two major domains ofmore » CAEV gp135. Mutation of isoleucine-166 to alanine in the putative loop B of gp135 increased the affinity of soluble gp135 for the CAEV receptor(s) and goat monoclonal antibody (Mab) F7-299 which recognizes an epitope overlapping the gp135 RBS. The I166A mutation also stabilized or exposed the F7-299 epitope in anionic detergent buffers, indicating that the I166A mutation induces conformational changes and stabilizes the RBS of soluble gp135 and enhances Mab F7-299 binding. In contrast, the affinity of a V1 deletion mutant of gp135 for the receptor and Mab F7-299 and its structural stability did not differ from that of the wild-type gp135. However, both the I166A mutation and the V1 deletion of gp135 increased cell-to-cell fusion activity and binding of Mab F7-299 to the oligomeric Env. Therefore, the CAEV gp135 RBS is protected from antibody binding by mechanisms both dependent and independent of Env oligomerization which are disrupted by the V1 deletion and the I166A mutation, respectively. In addition, we found a correlation between side-chain {beta}-branching at amino acid position 166 and binding of Mab F7-299 to oligomeric Env and cell-to-cell fusion, suggesting local secondary structure constraints in the region around isoleucine-166 as one determinant of gp135 RBS exposure and antibody binding.« less
  • A radioimmunoprecipitation (RIP) assay was developed to detect antibodies to the envelope glycoprotein gp120 of the human immunodeficiency virus (HIV-1). The assay, which utilized recombinant gp120 (rgp120), was quantitative, reproducible, and specific for antibodies to rgp120 or antibodies to native gp120 resulting from natural infection with HIV. Polyethylene glycol-8000 (PEG), used in the assay at a final concentration of 10% to precipitate immune complexes, was demonstrated to be effective in titering sera from different animal species. Provided samples were diluted at least 1:100, antibody titers could be determined either by the classical dilution method or by interpolation from a calibrationmore » curve prepared with a positive serum. The humoral response of animals immunized with rgp120 was monitored and a positive correlation was found between titers determined in the RIP assay and the ability of the sera to neutralize. In addition, RIP titers of HIV-positive human sera correlated very well with reactivity obtained in a commercial HIV immunoblot assay. The assay has the advantage of quantitation, fast turnaround time, and versatility.« less
  • HIV/SIV envelope glycoproteins mediate the first steps in viral infection. They are trimers of a membrane-anchored polypeptide chain, cleaved into two fragments known as gp120 and gp41. The structure of HIV gp120 bound with receptor (CD4) has been known for some time. We have now determined the structure of a fully glycosylated SIV gp120 envelope glycoprotein in an unliganded conformation by X-ray crystallography at 4.0 {angstrom} resolution. We describe here our experimental and computational approaches, which may be relevant to other resolution-limited crystallographic problems. Key issues were attention to details of beam geometry mandated by small, weakly diffracting crystals, andmore » choice of strategies for phase improvement, starting with two isomorphous derivatives and including multicrystal averaging. We validated the structure by analyzing composite omit maps, averaged among three distinct crystal lattices, and by calculating model-based, SeMet anomalous difference maps. There are at least four ordered sugars on many of the thirteen oligosaccharides.« less