Lipid composition but not curvature is a determinant of a low molecular mobility within HIV-1 lipid envelope

Abstract

Human Immunodeficiency Virus type-1 (HIV-1) acquires its lipid membrane from the plasma membrane of the infected cell from where it buds out. Previous studies have shown that the HIV-1 envelope is a very low mobility environment with the diffusion of incorporated proteins two orders of magnitude slower than in plasma membrane. One of the reasons for this difference is thought to be due to HIV-1 membrane composition that is characterised by a high degree of rigidity and lipid packing.To further refine the model of the molecular mobility on HIV-1 surface, we here investigated the relative importance of membrane composition and curvature in Large Unilamellar Vesicles of different composition and size (0.2-1 µm) by super-resolution STED microscopy-based fluorescence correlation spectroscopy (STED-FCS) analysis. We find that lipid composition and its rigidity but not membrane curvature play an important role in the decreased molecular mobility on vesicle surface thus confirming that this factor is an essential determinant of HIV-1 low surface mobility. Our results provide further insight into the dynamic properties of the surface of individual HIV-1 particles.

HIV-1 Gag specifically restricts PI(4,5)P2 and cholesterol mobility in living cells creating a nanodomain platform for virus assembly

“…on the scale of individual (< 140 nm) HIV-1 particles. For example, experiments employing a combination of super-resolution STED microscopy and fluorescence correlation spectroscopy (STED-FCS (10) or scanning STED-FCS, sSTED-FCS (11,12)) revealed a low mobility of molecules on HIV-1 surface (3) due to the high degree of lipid packing in the virus membrane (12,13). The retroviral protein Gag is thought to be a key player in altering the HIV-1 lipid environment as it is not only the main structural determinant of the particle assembly, but it also mediates interactions between assembling virus particle and plasma membrane lipids.…”

HIV-1 Gag specifically restricts PI(4,5)P2 and cholesterol mobility in living cells creating a nanodomain platform for virus assembly

“…How enveloped viruses acquire their lipid membrane shell is of great importance for their biogenesis and their capacity to infect cells. In the case of HIV-1, recently it has been shown that the envelope lipid composition was a determinant of low molecular mobility of the Env protein (3,13). Several works have been conducted to reveal different envelope viruses having their own unique lipid composition (2,4,6,36), implying their distinct biological requirements during infection, and suggesting their capacity in sorting specific host lipids into their virus membrane.…”