eEF2 and Ras-GAP SH3 domain-binding protein (G3BP1) modulate stress granule assembly during HIV-1 infection

Stress granules (SG) are translationally silent sites of RNA triage induced by environmental stresses including viral infection. Here we show that HIV-1 Gag blocks SG assembly irrespective of eIF2α-phosphorylation and even when SG assembly is forced by overexpression of Ras-GAP SH3 domain-binding protein (G3BP1) or TIAR. The overexposed loops in the N-terminal Capsid domain of Gag and host eukaryotic elongation factor 2 (eEF2) are found to be critical for the SG blockade via interaction. Moreover, Cyclophilin A (CypA) stabilizes the Gag-eEF2 association. eEF2 depletion not only lifts the SG blockade but also results in impaired virus production and infectivity. Gag also disassembles pre-formed SGs by recruiting G3BP1 thereby displacing eEF2, revealing another unsuspected virus-host interaction involved in this mechanism. Understanding how HIV-1 counters anti-viral stress responses will lay the groundwork for new therapeutic strategies to bolster host cell immune defences against HIV-1 and other pathogens.