Type I Phosphatidylinositol-4-Phosphate 5-Kinases α and γ Play a Key Role in Targeting HIV-1 Pr55 Gag to the Plasma Membrane

Abstract

PM specificity of Pr55 Gag membrane binding is mediated through the interaction of PI(4,5)P 2 with the matrix (MA) basic residues. It was shown that overexpression of a PI(4,5)P 2 -depleting enzyme strongly impaired PM localization of Pr55 Gag . However, cellular factors that control PI(4,5)P 2 production required for Pr55 Gag -PM targeting have not yet been characterized. In this study, by individually inhibiting PIP5K1 isoforms, we elucidated a correlation between PI(4,5)P 2 metabolism pathways mediated by PIP5K1 isoforms and the targeting of Pr55 Gag to the PM of TZM-bl HeLa cells. Confocal microscopy analyses of cells depleted from PIP5K1α and PIP5K1γ show a rerouting of Pr55 Gag to various intracellular compartments. Notably, Pr55 Gag is degraded by the proteasome and/or by the lysosomes in PIP5K1α-depleted cells, while Pr55 Gag is targeted to endosomal vesicles in PIP5K1γ-depleted cells. Thus, our results highlight, for the first time, the roles of PIP5K1α and PIP5K1γ as determinants of Pr55 Gag targeting to the PM.