Fig. 3: Mutations in Viet04 HA stabilize activation dynamics in HA2.
From: Host switching mutations in H5N1 influenza hemagglutinin suppress site-specific activation dynamics
A BN-PAGE monitoring the formation of high molecular weight oligomers after 1 hour incubation at various pH. Arrows indicate the highest pH where aggregation was observed. Acidification experiments were repeated twice with similar results. B Experiment overview. C Differences in HA dynamics upon acidification are mapped onto the structures of Viet04 WT (PDB 4BGW) and mutant (PDB 4BH2). Differences were determined using the total exchange for each peptide (% exchange summed across all timepoints). Peptides that become more dynamic at low pH are colored purple and peptides that become more protected are colored green. The degree of shading reflects moderate (15–35%) and large (>35%) differences in total exchange. Differences totaling less than 15% are colored white, signifying no change. Peptides that could not be monitored due to low signal intensity or overlapping ions are colored gray. Uptake plots for three peptides are shown to right for WT (dashed lines) and mutant (solid lines) at pH 7.4 (blue), pH 6.1 (orange), and pH 5.9 (red). Percent deuteration is shown as the average of two technical replicates and the SD is plotted as error bars. D Differences in HA dynamics between Viet04 WT and mutant at the lowest pH where exchange was measured, pH 6.1 and pH 5.9 respectively, are mapped onto the structure of Viet04 WT (PDB 4BGW). Peptides that become more dynamic in the mutant are colored pink and peptides that become more protected in the mutant are colored blue. The same threshold for differences was applied as in part (C). Uptake plots for three peptides are shown to the right. Percent deuteration is shown as the average of two technical replicates and the SD is plotted as error bars. E Cartoon representation of activation dynamics for Viet04 WT (top) and mutant (bottom) showing degrees of fusion peptide release and head domain opening based on dynamic profile. Blue stars estimate the site of mutations. Source data are provided as a Source data file.
