The various steps by which lipid-enveloped viruses enter or ‘fuse’ with a host cell require the coordination of receptor recognition, viral protein activation and large protein conformational changes that can drive membrane bilayer fusion. Here we report biochemical, structural and functional experiments on the protein complex that triggers activation of the EBV fusion protein (gB) and entry of Epstein-Barr Virus (EBV) into B cells of the immune system. Three viral glycoproteins (gH, gL and gp42) form a well-defined complex with host receptor (HLA). We isolated the complex biochemically and studied its assembly by BLI biosensor and electron microscopy methods. Previous crystal structures revealed a hydrophobic pocket (HP) on the gp42 surface that when mutated disrupts fusion with B cells, but the critical binding ligand remained unknown. Our experiments show that the gp42 HP interacts with gHgL and that mutations of the predicted HP contact residues on gHgL are detrimental for fusion. Constraints imposed by the triggering complex architecture relative to its predicted membrane anchors highlight a close approach and potential deformation of both viral and host membranes affected by HLA receptor binding as a prerequisite to viral entry.
Vyšlo v časopise: Assembly and Architecture of the EBV B Cell Entry Triggering Complex. PLoS Pathog 10(8): e32767. doi:10.1371/journal.ppat.1004309 Kategorie: Research Article prolekare.web.journal.doi_sk: https://doi.org/10.1371/journal.ppat.1004309
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