Self-assembly of influenza hemagglutinin: studies of ectodomain aggregation by in situ atomic force microscopy.

摘要: We have used in situ tapping mode atomic force microscopy (AFM) to study the structural morphology of two fragments influenza hemagglutinin protein bound supported bilayers. The proteins that we studied are bromelain-cleaved (BHA), corresponding full ectodomain protein, and FHA2, 127 amino acid N-terminal fragment HA2 subunit protein. While BHA is water soluble at neutral pH known bind membranes via specific interactions with a viral receptor, FHA2 can only be solubilized an appropriate detergent. Furthermore, readily absence receptor. Our AFM studies demonstrated that, when bilayers pH, both these self-assembled as single trimeric molecules. In acidification resulted further lateral association without large perturbation bilayer. contrast, remained largely unaffected by acidification, except areas exposed mica where it aggregated. Remarkably, results consistent previous observations promotes membrane fusion while induces liposome leakage low pH. presented here first example imaging envelope allowing characterization real-time self-assembly