生物化学

Membrane fusion is vital for entry of enveloped viruses into host cells as well as for direct viral cell-to-cell spread. To understand the fusion mechanism in more detail, we use an infection free system whereby fusion can be induced by a minimal set of the alphaherpesvirus pseudorabies virus (PrV) glycoproteins gB, gH and gL. Here, we describe an optimized protocol of a transient transfection based fusion assay to quantify cell-cell fusion induced by the PrV glycoproteins.

Interactions of lipids with proteins are essential events in the framework of biological membranes. Assessment of the affinity and specificity of protein-lipid binding can give useful information to elucidate cell membrane functions. Surface Plasmon Resonance (SPR) is a powerful technology to study macromolecular interactions, allowing direct and rapid determination of association and dissociation rates using small amounts of samples. An extensive range of binding analyses can be performed by SPR such as protein–protein, protein–membrane (lipids), protein–carbohydrate, protein–nucleic acid and even protein-small molecules. This protocol describes the binding of an antimicrobial protein (used as ligand) to a lipopolysaccharide (LPS) (used as analyte) after immobilization onto a CM sensor chip by amine coupling.

Dye release experiments are a widely used method to assess the interactions between membrane-active molecules and lipid membranes. Of particular interest is the ability to assess the degree of the lipid bilayer perturbation by simultaneously encapsulating dye of different sizes, such as dextrans grafted with a chromophore. In this assay, dextran linked to rhodamine or fluorescein are both encapsulated in lipid vesicles to allow quantifying the leakage of each dextran individually from a single sample. For instance, the size evaluation of the lipid pore formed by an antimicrobial peptide has been recently achieved using this protocol (Sani et al., 2013).

This is a protocol to examine in vitro protein-lipid binding using membrane strips coated with various lipids. It has been successfully used to study in vitro interaction between lipids and C. elegans proteins.