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Force Spectroscopy Shows Dynamic Binding of Influenza Hemagglutinin and Neuraminidase to Sialic Acid

Valentin Reiter-Scherer, Jose Luis Cuellar-Camacho, Sumati Bhatia Orcid Logo, Rainer Haag, Andreas Herrmann, Daniel Lauster, Jürgen P. Rabe

Biophysical Journal, Volume: 116, Issue: 6, Pages: 1037 - 1048

Swansea University Author: Sumati Bhatia Orcid Logo

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Abstract

The influenza A virus infects target cells through multivalent interactions of its major spike proteins, hemagglutinin (HA) and neuraminidase (NA), with the cellular receptor sialic acid (SA). HA is known to mediate the attachment of the virion to the cell, whereas NA enables the release of newly fo...

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Published in: Biophysical Journal
ISSN: 0006-3495
Published: Elsevier BV 2019
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa64870
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Abstract: The influenza A virus infects target cells through multivalent interactions of its major spike proteins, hemagglutinin (HA) and neuraminidase (NA), with the cellular receptor sialic acid (SA). HA is known to mediate the attachment of the virion to the cell, whereas NA enables the release of newly formed virions by cleaving SA from the cell. Because both proteins target the same receptor but have antagonistic functions, virus infection depends on a properly tuned balance of the kinetics of HA and NA activities for viral entry to and release from the host cell. Here, dynamic single-molecule force spectroscopy, based on scanning force microscopy, was employed to determine these bond-specific kinetics, characterized by the off rate koff, rupture length xβ and on rate kon, as well as the related free-energy barrier ΔG and the dissociation constant KD. Measurements were conducted using surface-immobilized HA and NA of the influenza A virus strain A/California/04/2009 and a novel, to our knowledge, synthetic SA-displaying receptor for functionalization of the force probe. Single-molecule force spectroscopy at force loading rates between 100 and 50,000 pN/s revealed most probable rupture forces of the protein-SA bond in the range of 10–100 pN. Using an extension of the widely applied Bell-Evans formalism by Friddle, De Yoreo, and co-workers, it is shown that HA features a smaller xβ, a larger koff and a smaller ΔG than NA. Measurements of the binding probability at increasing contact time between the scanning force microscopy force probe and the surface allow an estimation of KD, which is found to be three times as large for HA than for NA. This suggests a stronger interaction for NA-SA than for HA-SA. The biological implications in regard to virus binding to the host cell and the release of new virions from the host cell are discussed.
College: Faculty of Science and Engineering
Funders: We are grateful for financial support within the SFB765 granted by the Deutsche Forschungsgemeinschaft.
Issue: 6
Start Page: 1037
End Page: 1048