Acylation of the Influenza Hemagglutinin Modulates Fusion Activity

The influenza virus hemagglutinin (HA) contains three highly conserved cysteine residues at positions 551, 559, and 562 close to the carboxyl-terminus of the HA2 subunit which serve as palmitylation sites. Wild-type HA of influenza virus A/FPV/Rostock/34 (H7N1) and HA permutated by exchange of the a...

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Bibliographic Details
Published in:Virology (New York, N.Y.) N.Y.), 1998-09, Vol.248 (2), p.284-294
Main Authors: Fischer, Christian, Schroth-Diez, Britta, Herrmann, Andreas, Garten, Wolfgang, Klenk, Hans-Dieter
Format: Article
Language:English
Subjects:
Acylation
Amino Acid Sequence
Animals
Cells, Cultured
Cercopithecus aethiops
Giant Cells - virology
Hemagglutinin Glycoproteins, Influenza Virus - genetics
Hemagglutinin Glycoproteins, Influenza Virus - metabolism
Hemagglutinin Glycoproteins, Influenza Virus - physiology
influenza
Influenza A virus - metabolism
Influenza A virus - physiology
Membrane Fusion - physiology
Molecular Sequence Data
Mutation
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Summary:The influenza virus hemagglutinin (HA) contains three highly conserved cysteine residues at positions 551, 559, and 562 close to the carboxyl-terminus of the HA2 subunit which serve as palmitylation sites. Wild-type HA of influenza virus A/FPV/Rostock/34 (H7N1) and HA permutated by exchange of the acylated cysteine to serine residues were expressed in CV-1 cells by a SV40 vector system. Since density of immunostained HA on the cell surface measured by flow cytometric analysis did not differ between wild-type and acylation mutants, it was possible to compare acylation mutants and wild-type HA for their capacity to induce membrane fusion at low pH. The following observations were made: (1) lateral diffusion of a lipid-like fluorophore (R-18) from the erythrocyte membrane to the plasma membrane of cells expressing HA on the surface occurred equally well with mutants and wild type. (2) Diffusion of a low-molecular-weight fluorescent water-soluble probe (calcein) from erythrocytes into the cytoplasm of HA-expressing cells was not altered either. (3) However, depending on the position and the number of the deleted acylation sites, the mutants showed a reduced ability to induce syncytia. The data indicate that deacylation of the cytoplasmic tail has no measurable effect on the capacity of HA to induce membrane fusion and pore formation but that it suppresses syncytia formation.
ISSN:0042-6822
1096-0341
DOI:10.1006/viro.1998.9286