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    Linker and/or transmembrane regions of influenza A/Group-1, A/Group-2, and type B virus hemagglutinins are packed differently within trimers (2011)

    Art
    Zeitschriftenartikel / wissenschaftlicher Beitrag
    Autoren
    Kordyukova, Larisa V
    Serebryakova, Marina V
    Polyansky, Anton A
    Kropotkina, Ekaterina A
    Alexeevski, Andrei V
    Veit, Michael (WE 5)
    Efremov, Roman G
    Filippova, Irina Yu
    Baratova, Lyudmila A
    Quelle
    Biochimica et biophysica acta; 1808(7) — S. 1843–1854
    ISSN: 0006-3002
    Sprache
    Englisch
    Verweise
    DOI: 10.1016/j.bbamem.2011.03.005
    Pubmed: 21420932
    Kontakt
    Institut für Virologie

    Robert-von-Ostertag-Str. 7-13
    Gebäude 35
    14163 Berlin
    +49 30 838 51833
    viro@zedat.fu-berlin.de

    Abstract / Zusammenfassung

    Influenza virus hemagglutinin is a homotrimeric spike glycoprotein crucial for virions' attachment, membrane fusion, and assembly reactions. X-ray crystallography data are available for hemagglutinin ectodomains of various types/subtypes but not for anchoring segments. To get structural information for the linker and transmembrane regions of hemagglutinin, influenza A (H1-H16 subtypes except H8 and H15) and B viruses were digested with bromelain or subtilisin Carlsberg, either within virions or in non-ionic detergent micelles. Proteolytical fragments were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Within virions, hemagglutinins of most influenza A/Group-1 and type B virus strains were more susceptible to digestion with bromelain and/or subtilisin compared to A/Group-2 hemagglutinins. The cleavage sites were always located in the hemagglutinin linker sequence. In detergent, 1) bromelain cleaved hemagglutinin of every influenza A subtype in the linker region; 2) subtilisin cleaved Group-2 hemagglutinins in the linker region; 3) subtilisin cleaved Group-1 hemagglutinins in the transmembrane region; 4) both enzymes cleaved influenza B virus hemagglutinin in the transmembrane region. We propose that the A/Group-2 hemagglutinin linker and/or transmembrane regions are more tightly associated within trimers than type A/Group-1 and particularly type B ones. This hypothesis is underpinned by spatial trimeric structure modeling performed for transmembrane regions of both Group-1 and Group-2 hemagglutinin representatives. Differential S-acylation of the hemagglutinin C-terminal anchoring segment with palmitate/stearate residues possibly contributes to fine tuning of transmembrane trimer packing and stabilization since decreased stearate amount correlated with deeper digestion of influenza B and some A/Group-1 hemagglutinins.