Synchronized HIV assembly by tunable PIP2 changes reveals PIP2 requirement for stable Gag anchoring

HIV-1 assembles at the plasma membrane (PM) of infected cells. PM association of the main structural protein Gag depends on its myristoylated MA domain and PM PI(4,5)P-2. Using a novel chemical biology tool that allows rapidly tunable manipulation of PI(4,5)P-2 levels in living cells, we show that depletion of PI(4,5)P-2 completely prevents Gag PM targeting and assembly site formation. Unexpectedly, PI(4,5)P-2 depletion also caused loss of pre-assembled Gag lattices from the PM. Subsequent restoration of PM PI(4,5)P-2 reinduced assembly site formation even in the absence of new protein synthesis, indicating that the dissociated Gag molecules remained assembly competent. These results reveal an important role of PI(4,5)P-2 for HIV-1 morphogenesis beyond Gag recruitment to the PM and suggest a dynamic equilibrium of Gag-lipid interactions. Furthermore, they establish an experimental system that permits synchronized induction of HIV-1 assembly leading to induced production of infectious virions by targeted modulation of Gag PM targeting.