Title: Gp41 dynamically interacts with the TCR in the immune synapse and promotes T cell activation
Author: Oren Yakovian
The HIV-1 glycoprotein gp41 critically mediates CD4+ T-cell infection by HIV-1 during viral entry, assembly, and release. Although multiple immune-regulatory activities of gp41 have been reported, the underlying mechanisms of these activities remain poorly understood. Here we employed multi-colour single molecule localization microscopy (SMLM) to resolve interactions of gp41 proteins with cellular proteins at the plasma membrane (PM) of fixed and live T-cells with resolution of ~20-30nm. We observed that gp41 clusters dynamically associated with the T cell antigen receptor (TCR) at the immune synapse upon TCR stimulation. This interaction, confirmed by FRET, depended on the virus clone, was reduced by the gp41 ectodomain in tight contacts, and was completely abrogated by mutation of the gp41 transmembrane domain. Strikingly, gp41 preferentially colocalized with phosphorylated TCRs at the PM of activated T-cells and promoted TCR phosphorylation. Gp41 expression also enhanced CD69 upregulation, followed by massive cell death after 48hrs. Our results shed new light on HIV-1 assembly mechanisms at the PM of host T-cells and its relation to TCR stimulation, and thus could indicate new ways for intervening with viral interaction with T-cell signalling, its budding, and repeated infection.