THE INTERFACIAL PROPERTIES OF THE HIV-1 GAG MATRIX DOMAIN ARE MODULATED BY PROTEIN MYRISTOYLATION AND NUCLEIC ACID BINDING

PÉREZ SOCAS, LUIS BENITO; AMBROGGIO E. E.

BUENOS AIRES

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

The specific traffic and assembly of the HIV-1 GAG proteinat the plasma membrane (PM) is tightly regulated by the myristoylationof its matrix domain (GAGMA) and its binding to RNA. WhenGAG reaches the PM a perfect protein monolayer is formed. Understandinghow this layer is constituted and stabilized is relevant to developnew strategies aiming to interrupt the gemmation of new viralparticles at the membrane. For this reason, we studied the stability,thermodynamics and the topography if this first protein layer fromLangmuir monolayers composed of the myristoylated or unmyristoylatedversions of GAGMA in the presence or the absence of a singlestrand DNA (ssDNASel25), an analog of the Sel25 RNA sequence,that tightly binds GAGMA. We also used a similar approach to studymonolayers of GAGMA -derived peptides (first 21 resides of GAGMA)in their myristoylated and unmyristoylated forms. Our results showthat the protein/peptide films are destabilized by the presence ofssDNASel25, inducing solubilization of the film components into thebulk phase. In addition, the oligonucleotide affects the protein-proteinor peptide-peptide lateral interactions provoking interfacial topographychanges of the monolayers, visualized by Brewster anglemicroscopy. Additionally, we show how the myristoyl group has majoreffects on the lateral stability and the elasticity of the monolayers.Altogether, here we propose a general model for GAGMA interfacialassociation, considering the effect of myristoylation and the interactionwith oligonucleotides. The model proposes a new role of GAGMAbased on the lateral stabilization of protein monolayers.Keywords: Human immunodeficiency virus, HIV-1 GAG matrixdomain, Oligonucleotide interaction, Brewster-angle microscopy,Langmuir monolayers.