Figure 4. Increased N-terminal domain (NTD) dynamics in Alpha S.
(A) Relative fractional uptake (Dex = 10 min) for Alpha S mapped onto an spike (S) protein structure with three down RBDs (PDB ID: 6VXX) coverage map is shown in Figure 4—figure supplement 1). Deuterium exchange heat map (gradient of white (0%) -red (70%) as mapped on S structure (PDB ID: 6VXX). (B) Differences in deuterium exchange (Δ RFU) (Dex = 10 min) for Alpha S minus D614G S were mapped onto an S structure (PDB ID: 6VXX). Shades of blue correspond to negative differences in deuterium exchange and shades of red correspond to a positive difference in deuterium exchange. (C–E) Stacked mass spectra for peptides 92–103, 177–191, and 900–913 with the undeuterated mass spectral envelope as a reference, 1 min and 10 min exchange (left to right). For each peptide, the top row contains spectra for D614G S and the bottom row contains spectra for Alpha S. Absolute intensities are indicated at the top right of each spectrum. (F) Differences in deuterium exchange (deuterons) mapped at peptide resolution from N to C terminus for Alpha S minus D614G S are shown in difference plots for 1-, 2-, 10-, and 30 min exchange. Select peptides showing significant differences in exchange are annotated. Significance was determined by hybrid significance testing (p<0.01, Figure 4—figure supplement 2). Differences are tabulated in Figure 4—source data 1 with corresponding peptide numbers* shown on the x-axis of the difference plot.