Structure and Dynamics of Activated State Conformational Ensembles for the Influenza Hemagglutinin Fusion Peptide

Wednesday, October 10, 2012 — Poster Session II
Noon – 2:00 p.m	Natcher Conference Center, Building 45	NIDDK	STRUCTBIO-3

* FARE Award Winner

Authors

• JL Lorieau
• JM Louis
• CD Schwieters
• A Bax

Abstract

The influenza hemagglutinin fusion domain, which constitute the first 23 residues of the HA2 subunit, is highly conserved, hydrophobic and fulfils the necessary role of latching into the host endosomal membrane and catalyzing the initial stages of fusion. The peptide adopts a closed helical-hairpin structure. At low pH, where the fusion reaction is activated, we show that the fusion peptide appears to visit an activated 'dark' state. We characterize the structures of the activated states with RDCs and NOEs, using a glycine to alanine mutation (G8A) to populate the activated state. With 1H T1(rho) experiments, it is found that the conformational interchange to the activated state has a time constant of 28 us at 12oC. This activated state could play a role in the later stages of the fusion process, where it has been postulated that many fusion domains must assemble to form a pore structure.

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