Structure-Based Identification and Neutralization Mechanism of Tyrosine Sulfate Mimetics That Inhibit HIV-1 Entry

Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States.
ACS Chemical Biology (Impact Factor: 5.33). 08/2011; 6(10):1069-77. DOI: 10.1021/cb200068b
Source: PubMed


Tyrosine sulfate-mediated interactions play an important role in HIV-1 entry. After engaging the CD4 receptor at the cell surface, the HIV-1 gp120 glycoprotein binds to the CCR5 co-receptor via an interaction that requires two tyrosine sulfates, at positions 10 and 14 in the CCR5-N terminus. Building on previous structure determinations of this interaction, here we report the targeting of these tyrosine sulfate binding sites for drug design through in silico screening of small molecule libraries, identification of lead compounds, and characterization of biological activity. A class of tyrosine sulfate-mimicking small molecules containing a "phenyl sulfonate-linker-aromatic" motif was identified that specifically inhibited binding of gp120 to the CCR5-N terminus as well as to sulfated antibodies that recognize the co-receptor binding region on gp120. The most potent of these compounds bound gp120 with low micromolar affinity and its CD4-induced conformation with K(D)'s as tight as ∼50 nM. Neutralization experiments suggested the targeted site to be conformationally inaccessible prior to CD4 engagement. Primary HIV-1 isolates were weakly neutralized, preincubation with soluble CD4 enhanced neutralization, and engineered isolates with increased dependence on the N terminus of CCR5 or with reduced conformational barriers were neutralized with IC(50) values as low as ∼1 μM. These results reveal the potential of targeting the tyrosine sulfate interactions of HIV-1 and provide insight into how mechanistic barriers, evolved by HIV-1 to evade antibody recognition, also restrict small-molecule-mediated neutralization.

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Available from: Mark K Louder, Oct 05, 2015
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    • "Although protein-protein interfaces are often relatively featureless and devoid of traditional cavities into which a small molecule can dock, the realization that the gp120 coreceptor binding site displays a restricted number of functionally important basic residues has very recently attracted the attention of many studies. Many of them reported that anionic molecules target the CD4i epitope, as shown by their ability to competitively inhibit mAb 17b binding with IC 50 in the 1–100 mM range (Acharya et al., 2011; Brower et al., 2009; Cohen et al., 2008; Cormier et al., 2000; Crublet et al., 2008; Dervillez et al., 2010; Farzan et al., 2000; Kwong et al., 2011; Seitz et al., 2010). HS belongs to this class of CD4i domain targeting molecules (Crublet et al., 2008), and a highly sulfated and regular sequence comprising 12 monosaccharide units has been recently prepared. "
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