9cu5 | pdb_00009cu5
LJF-085 Fab in complex with HIV Env JRFL NFL TD CC3+ trimer and 35O22 Fab
Structural highlights
FunctionQ75760_HV1 Envelope glycoprotein gp160: Oligomerizes in the host endoplasmic reticulum into predominantly trimers. In a second time, gp160 transits in the host Golgi, where glycosylation is completed. The precursor is then proteolytically cleaved in the trans-Golgi and thereby activated by cellular furin or furin-like proteases to produce gp120 and gp41.[HAMAP-Rule:MF_04083] Surface protein gp120: Attaches the virus to the host lymphoid cell by binding to the primary receptor CD4. This interaction induces a structural rearrangement creating a high affinity binding site for a chemokine coreceptor like CXCR4 and/or CCR5. Acts as a ligand for CD209/DC-SIGN and CLEC4M/DC-SIGNR, which are respectively found on dendritic cells (DCs), and on endothelial cells of liver sinusoids and lymph node sinuses. These interactions allow capture of viral particles at mucosal surfaces by these cells and subsequent transmission to permissive cells. HIV subverts the migration properties of dendritic cells to gain access to CD4+ T-cells in lymph nodes. Virus transmission to permissive T-cells occurs either in trans (without DCs infection, through viral capture and transmission), or in cis (following DCs productive infection, through the usual CD4-gp120 interaction), thereby inducing a robust infection. In trans infection, bound virions remain infectious over days and it is proposed that they are not degraded, but protected in non-lysosomal acidic organelles within the DCs close to the cell membrane thus contributing to the viral infectious potential during DCs' migration from the periphery to the lymphoid tissues. On arrival at lymphoid tissues, intact virions recycle back to DCs' cell surface allowing virus transmission to CD4+ T-cells.[HAMAP-Rule:MF_04083] Transmembrane protein gp41: Acts as a class I viral fusion protein. Under the current model, the protein has at least 3 conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During fusion of viral and target intracellular membranes, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes. Complete fusion occurs in host cell endosomes and is dynamin-dependent, however some lipid transfer might occur at the plasma membrane. The virus undergoes clathrin-dependent internalization long before endosomal fusion, thus minimizing the surface exposure of conserved viral epitopes during fusion and reducing the efficacy of inhibitors targeting these epitopes. Membranes fusion leads to delivery of the nucleocapsid into the cytoplasm.[HAMAP-Rule:MF_04083] Publication Abstract from PubMedThe elicitation of cross-neutralizing antibodies to the HIV-1 envelope glycoprotein (Env) by vaccination remains a major challenge. Here, we immunized previously Env-immunized nonhuman primates with a series of near-native trimers that possessed N-glycan deletions proximal to the conserved CD4 binding site (CD4bs) to focus B cells to this region. Following heterologous boosting with fully glycosylated trimers, we detected tier 2 cross-neutralizing activity in the serum of several animals. Isolation of 185 matched heavy- and light-chain sequences from Env-binding memory B cells from an early responder identified a broadly neutralizing antibody lineage, LJF-0034, which neutralized nearly 70% of an 84-member HIV-1 global panel. High-resolution cryoelectron microscopy (cryo-EM) structures revealed a bifurcated binding mode that bridged the CD4bs to V3 across the gp120:120 interface on two adjacent protomers, evading the proximal N276 glycan impediment to the CD4bs, allowing neutralization breadth. This quaternary epitope defines a potential target for future HIV-1 vaccine development. Vaccination of nonhuman primates elicits a broadly neutralizing antibody lineage targeting a quaternary epitope on the HIV-1 Env trimer.,Schleich FA, Bale S, Guenaga J, Ozorowski G, Adori M, Lin X, Castro Dopico X, Wilson R, Chernyshev M, Cotgreave AT, Mandolesi M, Cluff J, Doyle ED, Sewall LM, Lee WH, Zhang S, O'Dell S, Healy BS, Lim D, Lewis VR, Ben-Akiva E, Irvine DJ, Doria-Rose NA, Corcoran M, Carnathan D, Silvestri G, Wilson IA, Ward AB, Karlsson Hedestam GB, Wyatt RT Immunity. 2025 May 5:S1074-7613(25)00173-6. doi: 10.1016/j.immuni.2025.04.010. PMID:40339576[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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