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-Structure paper
Title | Visualization of the HIV-1 Env glycan shield across scales. |
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Journal, issue, pages | Proc Natl Acad Sci U S A, Vol. 117, Issue 45, Page 28014-28025, Year 2020 |
Publish date | Nov 10, 2020 |
Authors | Zachary T Berndsen / Srirupa Chakraborty / Xiaoning Wang / Christopher A Cottrell / Jonathan L Torres / Jolene K Diedrich / Cesar A López / John R Yates / Marit J van Gils / James C Paulson / Sandrasegaram Gnanakaran / Andrew B Ward / |
PubMed Abstract | The dense array of N-linked glycans on the HIV-1 envelope glycoprotein (Env), known as the "glycan shield," is a key determinant of immunogenicity, yet intrinsic heterogeneity confounds typical ...The dense array of N-linked glycans on the HIV-1 envelope glycoprotein (Env), known as the "glycan shield," is a key determinant of immunogenicity, yet intrinsic heterogeneity confounds typical structure-function analysis. Here, we present an integrated approach of single-particle electron cryomicroscopy (cryo-EM), computational modeling, and site-specific mass spectrometry (MS) to probe glycan shield structure and behavior at multiple levels. We found that dynamics lead to an extensive network of interglycan interactions that drive the formation of higher-order structure within the glycan shield. This structure defines diffuse boundaries between buried and exposed protein surface and creates a mapping of potentially immunogenic sites on Env. Analysis of Env expressed in different cell lines revealed how cryo-EM can detect subtle changes in glycan occupancy, composition, and dynamics that impact glycan shield structure and epitope accessibility. Importantly, this identified unforeseen changes in the glycan shield of Env obtained from expression in the same cell line used for vaccine production. Finally, by capturing the enzymatic deglycosylation of Env in a time-resolved manner, we found that highly connected glycan clusters are resistant to digestion and help stabilize the prefusion trimer, suggesting the glycan shield may function beyond immune evasion. |
External links | Proc Natl Acad Sci U S A / PubMed:33093196 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.1 - 3.5 Å |
Structure data | EMDB-22108, PDB-6x9r: EMDB-22109, PDB-6x9s: EMDB-22110, PDB-6x9t: EMDB-22111, PDB-6x9u: EMDB-22112, PDB-6x9v: |
Chemicals | ChemComp-NAG: |
Source |
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Keywords | VIRAL PROTEIN/IMMUNE SYSTEM / HIV-1 / Envelope / glycoprotein / spike / VIRAL PROTEIN-IMMUNE SYSTEM complex / vaccine |