STRUCTURE OF INFLUENZA HEMAGGLUTININ AT THE PH OF MEMBRANE-FUSION

Low pH induces a conformational change in the influenza virus haemaggl utinin, which then mediates fusion of the viral and host cell membrane s. The three-dimensional structure of a fragment of the haemagglutinin in this conformation reveals a major refolding of the secondary and t ertiary structure of the molecule. The apolar fusion peptide moves at least 100 Angstrom to one tip of the molecule. At the other end a heli cal segment unfolds, a subdomain relocates reversing the chain directi on, and part of the structure becomes disordered.