Increased Whole Cell Conductance and Sodium Selectivity in Xenopus Oocytes Incubated with Exogenous Lentivirus Lytic Peptide 1 (LLP-1) Domain of the HIV-1 gp41 protein

Nova Southeastern University, Davie, Florida, USA

Objective. This study was conducted to determine if the LLP-1 domain of the HIV gp41 protein increased whole cell conductance of Xenopus laevis oocytes and determine which ion(s) are responsible for the increased conductance. Background. Many attempts have been made to explain the “balloon degeneration” of HIV infected cells observed in culture. The LLP-1 domain of the cytoplasmic tail of gp41 models to form an amphipathic α-helix. Previous work show exogenous LLP-1 peptides form an α-helical structure in the presence of lipids and can disrupt large unilamellar vesicles (LUVs). Methods. For this study, Xenopus laevis oocytes were incubated with exogenous LLP-1 peptides, then whole cell conductances were measured by two electrode, whole-cell voltage clamping in a continuously circulating medium. Medium that lacked one of Na+, K+, Cl-, or H+ could be substituted to determine each ion’s contribution to the increased conductance observed. Results. 25 and 75μM concentrations of peptide increased whole cell conductances and shifted reversal potentials of resting membranes to more positive resting potentials. Removing Na+ from the medium decreased whole cell conductance and made resting membrane potentials more negative. Conclusion. LLP-1 peptides may act as a pore to allow increased Na+ across the membrane.