GPI-anchored influenza hemagglutinin induces hemifusion to both red blood cell and planar bilayer membranes - PubMed (original) (raw)

GPI-anchored influenza hemagglutinin induces hemifusion to both red blood cell and planar bilayer membranes

G B Melikyan et al. J Cell Biol. 1995 Nov.

Abstract

Under fusogenic conditions, fluorescent dye redistributed from the outer monolayer leaflet of red blood cells (RBCs) to cells expressing glycophosphatidylinositol-anchored influenza virus hemagglutinin (GPI-HA) without transfer of aqueous dye. This suggests that hemifusion, but not full fusion, occurred (Kemble, G. W., T. Danieli, and J. M. White. 1994. Cell. 76:383-391). We extended the evidence for hemifusion by labeling the inner monolayer leaflets of RBCs with FM4-64 and observing that these inner leaflets did not become continuous with GPI-HA-expressing cells. The region of hemifusion-separated aqueous contents, the hemifusion diaphragm, appeared to be extended and was long-lived. But when RBCs hemifused to GPI-HA-expressing cells were osmotically swollen, some diaphragms were disrupted, and spread of both inner leaflet and aqueous dyes was observed. This was characteristic of full fusion: inner leaflet and aqueous probes spread to cells expressing wild-type HA (wt-HA). By simultaneous video fluorescence microscopy and time-resolved electrical admittance measurements, we rigorously demonstrated that GPI-HA-expressing cells hemifuse to planar bilayer membranes: lipid continuity was established without formation of fusion pores. The hemifusion area became large. In contrast, for cells expressing wt-HA, before lipid dye spread, fusion pores were always observed, establishing that full fusion occurred. We present an elastic coupling model in which the ectodomain of wt-HA induces hemifusion and the transmembrane domain, absent in the GPI-HA-expressing cells, mediates full fusion.

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References

    1. J Cell Biol. 1977 Apr;73(1):161-81 - PubMed
    1. Science. 1975 Aug 1;189(4200):347-58 - PubMed
    1. Nature. 1981 Jan 29;289(5796):366-73 - PubMed
    1. Biophys J. 1983 Mar;41(3):251-7 - PubMed
    1. Virology. 1983 Jun;127(2):361-73 - PubMed

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