Structural highlights
Function
[Q4QX39_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.[RuleBase:RU004292][SAAS:SAAS00139820] 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.[SAAS:SAAS00140087]
Publication Abstract from PubMed
The conserved membrane-proximal external region (MPER) of the HIV-1 gp41 envelope protein is the established target for very rare but broadly neutralizing monoclonal antibodies (NAbs) elicited during natural human infection. Nevertheless attempts to generate an HIV-1 neutralizing antibody response with immunogens bearing MPER epitopes have met with limited success. Here we show that the MPER peptide (residues 662-683) forms a labile alpha-helical trimer in aqueous solution and report the crystal structure of this autonomous folding subdomain stabilized by addition of a C-terminal isoleucine-zipper motif. The structure reveals a parallel triple-stranded coiled coil in which the neutralization epitope residues are buried within the interface between the associating MPER helices. Accordingly, both the 2F5 and 4E10 NAbs recognize the isolated MPER peptide but fail to bind the trimeric MPER subdomain. We propose that the trimeric MPER structure represents the pre-fusion conformation of gp41, preceding the putative prehairpin intermediate and the post-fusion trimer-of-hairpins structure. As such, the MPER trimer should inform the design of new HIV-1 immunogens to elicit broadly neutralizing antibodies.
Structure of the HIV-1 gp41 Membrane-Proximal Ectodomain Region in a Putative Prefusion Conformation.,Lu M, Liu J, Deng Y, Dey A, Moore J Biochemistry. 2009 Feb 18. PMID:19226163[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lu M, Liu J, Deng Y, Dey A, Moore J. Structure of the HIV-1 gp41 Membrane-Proximal Ectodomain Region in a Putative Prefusion Conformation. Biochemistry. 2009 Feb 18. PMID:19226163 doi:10.1021/bi802303b
