Estimation by radiation inactivation of the size of functional units governing Sendai and influenza virus fusion

Biochemistry ◽  
1987 ◽  
Vol 26 (19) ◽  
pp. 6223-6227 ◽  
Author(s):  
Keiko Bundo-Morita ◽  
Suzanne Gibson ◽  
John Lenard
2000 ◽  
Vol 74 (6) ◽  
pp. 2714-2720 ◽  
Author(s):  
Susanne Günther-Ausborn ◽  
Pieter Schoen ◽  
Ingrid Bartoldus ◽  
Jan Wilschut ◽  
Toon Stegmann

ABSTRACT Membrane fusion mediated by influenza virus hemagglutinin (HA) is believed to proceed via the cooperative action of multiple HA trimers. To determine the minimal number of HA trimers required to trigger fusion, and to assess the importance of cooperativity between these HA trimers, we have generated virosomes containing coreconstituted HAs derived from two strains of virus with different pH dependencies for fusion, X-47 (optimal fusion at pH 5.1; threshold at pH 5.6) and A/Shangdong (optimal fusion at pH 5.6; threshold at pH 6.0), and measured fusion of these virosomes with erythrocyte ghosts by a fluorescence lipid mixing assay. Virosomes with different X-47-to-A/Shangdong HA ratios, at a constant HA-to-lipid ratio, showed comparable ghost-binding activities, and the low-pH-induced conformational change of A/Shangdong HA did not affect the fusion activity of X-47 HA. The initial rate of fusion of these virosomes at pH 5.7 increased directly proportional to the surface density of A/Shangdong HA, and a single A/Shangdong trimer per virosome appeared to suffice to induce fusion. The reciprocal of the lag time before the onset of fusion was directly proportional to the surface density of fusion-competent HA. These results support the notion that there is no cooperativity between HA trimers during influenza virus fusion.


Author(s):  
Susanne Schreiber ◽  
Kai Ludwig ◽  
Hermann-Georg Holzhütter ◽  
Andreas Herrmann

2002 ◽  
Vol 277 (23) ◽  
pp. 20461-20467 ◽  
Author(s):  
Bolormaa Baljinnyam ◽  
Britta Schroth-Diez ◽  
Thomas Korte ◽  
Andreas Herrmann
Keyword(s):  

1997 ◽  
Vol 53 (7) ◽  
pp. 995-1003 ◽  
Author(s):  
Pieter Schosen ◽  
Jeroen Corver ◽  
Dirk K.F. Meijer ◽  
Jan Wilschut ◽  
Pieter J. Swart
Keyword(s):  

2011 ◽  
Vol 7 (10) ◽  
pp. 2741 ◽  
Author(s):  
Maria Pamela Dobay ◽  
Akos Dobay ◽  
Johnrob Bantang ◽  
Eduardo Mendoza

1992 ◽  
Vol 12 (5) ◽  
pp. 397-406 ◽  
Author(s):  
Thomas Korte ◽  
Kai Ludwig ◽  
Andreas Herrmann

The hydropathy profile of hemagglutinin (HA) subunits HA1 and HA2 of influenza virus X31 and A/PR 8/34 is analyzed at different pH. At neutral pH (7.4) pronounced hydrophobic sequences of HA correspond to the N-terminus and the transmembrane spanning sequence of HA2. At pH 5.0 where influenza virus is known to fuse with biological membranes several hydrophobic sequences in the ectodomain exist which are comparable in both the hydrophobicity and length of the N-terminus of HA2. It is suggested that these hydrophobic stretches are important for the fusion complex, in addition to the N-terminal site of HA2.


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