Sa. Tatulian et Lk. Tamm, REVERSIBLE PH-DEPENDENT CONFORMATIONAL CHANGE OF RECONSTITUTED INFLUENZA HEMAGGLUTININ, Journal of Molecular Biology, 260(3), 1996, pp. 312-316
Fusion between influenza virus and cell membranes is mediated bf a maj
or add-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 w
e show bf polarized infrared spectroscopy that the previously describe
d acid-induced inclination of HA reconstituted in supported phospholip
id bilayers is reversible in the absence, but irreversible in the pres
ence, of bound target membranes. We also demonstrate reversible pH-dep
endent changes in the capability of reconstituted HA to bind target me
mbranes. These results support a thermodynamically controlled mechanis
m of the conformational change of HA and provide new insight into the
understanding of the energetics of influenza-mediated membrane fusion.
(C) 1996 Academic Press Limited