Reversible pH-dependent conformational change of reconstituted influenza hemagglutinin.
Fusion between influenza virus and cell membranes is mediated by a major acid-induced conformational change of the spike glycoprotein of the viral envelope, hemagglutinin (HA). The conformational change of HA is commonly believed to be a kinetically controlled irreversible process, although the experimental evidence for this is controversial. Here we show by polarized infrared spectroscopy that the previously described acid-induced inclination of HA reconstituted in supported phospholipid bilayers is reversible in the absence, but irreversible in the presence, of bound target membranes. We also demonstrate reversible pH-dependent changes in the capability of reconstituted HA to bind target membranes. These results support a thermodynamically controlled mechanism of the conformational change of HA and provide new insight into the understanding of the energetics of influenza-mediated membrane fusion.
Tatulian
S A
SA
Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
Tamm
L K
LK
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009975:Orthomyxoviridae / Q000737:chemistry*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006389:Hemagglutinins, Viral