Tatulian S A, Tamm L K
Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
J Mol Biol. 1996 Jul 19;260(3):312-6. doi: 10.1006/jmbi.1996.0402.
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.
流感病毒与细胞膜之间的融合由病毒包膜刺突糖蛋白血凝素（HA）主要的酸诱导构象变化介导。虽然关于此的实验证据存在争议，但HA的构象变化通常被认为是一个动力学控制的不可逆过程。在这里，我们通过偏振红外光谱表明，先前描述的在支持的磷脂双层中重构的HA的酸诱导倾斜在没有结合靶膜时是可逆的，但在有结合靶膜时是不可逆的。我们还证明了重构的HA结合靶膜能力的可逆pH依赖性变化。这些结果支持了HA构象变化的热力学控制机制，并为理解流感介导的膜融合的能量学提供了新的见解。
