Mechanism of Membrane fusion induced by influenza hemagglutininThe influenza virus surface is coated with a hemagglutinin protein (HA). Virus infection begins with the binding of HA to the sialic acid receptors on the surface of the target cell. After the internalization of the virus through receptor-mediated endocytosis, HA mediates fusion of the viral membrane with the endosomal membrane to allow the passage of the viral genome into the host cytoplasm. A key step in this fusion process is the activation of HA from the native state to the fusogenic state. This transition is triggered by the mildly acidic pH in the mature endosome.
The method of site-specific cysteine-cysteine cross linking the spin labeling electron paramagnetic resonance (EPR) technique have proven useful in studying secondary, tertiary, and quaternary structures of membrane proteins. We use these two promising techniques to investigate the dynamics and conformation of the membrane-interacting domain of HA of influenza virus.
The peripheral part of this domain (aa 1-127: FHA2) is expressed in E. Coli and cysteine mutants were generated using site-directed mutagenesis for crosslinking and EPR. Studies of FHA2 using these two method are in progress.