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6x9u

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HIV-1 Envelope Glycoprotein BG505 SOSIP.664, expressed in HEK293S cells and partially deglycosylated by endoglycosidase H, in complex with RM20A3 Fab

Structural highlights

6x9u is a 4 chain structure with sequence from Human immunodeficiency virus 1 and Macaca mulatta. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.2Å
Ligands:	, ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

Q2N0S6_9HIV1 The envelope glyprotein gp160 precursor down-modulates cell surface CD4 antigen by interacting with it in the endoplasmic reticulum and blocking its transport to the cell surface (By similarity).[RuleBase:RU004292][SAAS:SAAS000328_004_020447] The gp120-gp41 heterodimer allows rapid transcytosis of the virus through CD4 negative cells such as simple epithelial monolayers of the intestinal, rectal and endocervical epithelial barriers. Both gp120 and gp41 specifically recognize glycosphingolipids galactosyl-ceramide (GalCer) or 3' sulfo-galactosyl-ceramide (GalS) present in the lipid rafts structures of epithelial cells. Binding to these alternative receptors allows the rapid transcytosis of the virus through the epithelial cells. This transcytotic vesicle-mediated transport of virions from the apical side to the basolateral side of the epithelial cells does not involve infection of the cells themselves (By similarity).[SAAS:SAAS000328_004_240990]

Publication Abstract from PubMed

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.

Visualization of the HIV-1 Env glycan shield across scales.,Berndsen ZT, Chakraborty S, Wang X, Cottrell CA, Torres JL, Diedrich JK, Lopez CA, Yates JR 3rd, van Gils MJ, Paulson JC, Gnanakaran S, Ward AB Proc Natl Acad Sci U S A. 2020 Nov 10;117(45):28014-28025. doi:, 10.1073/pnas.2000260117. Epub 2020 Oct 22. PMID:33093196^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Berndsen ZT, Chakraborty S, Wang X, Cottrell CA, Torres JL, Diedrich JK, López CA, Yates JR 3rd, van Gils MJ, Paulson JC, Gnanakaran S, Ward AB. Visualization of the HIV-1 Env glycan shield across scales. Proc Natl Acad Sci U S A. 2020 Nov 10;117(45):28014-28025. PMID:33093196 doi:10.1073/pnas.2000260117