Detection of closed influenza virus hemagglutinin fusion peptide structures in membranes by backbone 13CO-15N rotational-echo double-resonance solid-state NMR

Solid-state NMR spectroscopy is an established experimental technique which is used for the characterization of structural and dynamic properties of materials in their native state. Many types of solid-state NMR experiments have been used to characterize both lithium-based and sodium-based solid polymer and polymer–ceramic hybrid electrolyte materials. This review describes several solid-state NMR experiments that are commonly employed in the analysis of these systems: pulse field gradient NMR, electrophoretic NMR, variable temperature T1 relaxation, T2 relaxation and linewidth analysis, exchange spectroscopy, cross polarization, Rotational Echo Double Resonance, and isotope enrichment. In this review, each technique is introduced with a short description of the pulse sequence, and examples of experiments that have been performed in real solid-state polymer and/or hybrid electrolyte systems are provided. The results and conclusions of these experiments are discussed to inform readers of the strengths and weaknesses of each technique when applied to polymer and hybrid electrolyte systems. It is anticipated that this review may be used to aid in the selection of solid-state NMR experiments for the analysis of these systems.

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Testing topological models for the membrane penetration of the fusion peptide of influenza virus hemagglutinin

FEBS Letters ◽

10.1016/0014-5793(89)81574-1 ◽

1989 ◽

Vol 257 (2) ◽

pp. 369-372 ◽

Cited By ~ 33

Author(s):

Josef Brunner

Keyword(s):

Influenza Virus ◽

Fusion Peptide ◽

Membrane Penetration ◽

Influenza Virus Hemagglutinin ◽

Topological Models

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New Insights into the Spring-Loaded Conformational Change of Influenza Virus Hemagglutinin

Journal of Virology ◽

10.1128/jvi.76.9.4456-4466.2002 ◽

2002 ◽

Vol 76 (9) ◽

pp. 4456-4466 ◽

Cited By ~ 42

Author(s):

Jennifer A. Gruenke ◽

R. Todd Armstrong ◽

William W. Newcomb ◽

Jay C. Brown ◽

Judith M. White

Keyword(s):

Influenza Virus ◽

Conformational Change ◽

Conformational Changes ◽

Limited Proteolysis ◽

Coiled Coil ◽

Fusion Peptide ◽

Wild Type ◽

Influenza Virus Hemagglutinin ◽

Target Membrane ◽

Mutant Forms

ABSTRACT Influenza virus hemagglutinin undergoes a conformational change in which a loop-to-helix “spring-loaded” conformational change forms a coiled coil that positions the fusion peptide for interaction with the target bilayer. Previous work has shown that two proline mutations designed to disrupt this change disrupt fusion but did not determine the basis for the fusion defect. In this work, we made six additional mutants with single proline substitutions in the region that undergoes the spring-loaded conformational change and two additional mutants with double proline substitutions in this region. All double mutants were fusion inactive. We analyzed one double mutant, F63P/F70P, as an example. We observed that F63P/F70P undergoes key low-pH-induced conformational changes and binds tightly to target membranes. However, limited proteolysis and electron microscopy observations showed that the mutant forms a coiled coil that is only ∼50% the length of the wild type, suggesting that it is splayed in its N-terminal half. This work further supports the hypothesis that the spring-loaded conformational change is necessary for fusion. Our data also indicate that the spring-loaded conformational change has another role beyond presenting the fusion peptide to the target membrane.

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