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. 2021 Feb 8;10:e63646. doi: 10.7554/eLife.63646

Figure 4. Angiotensin-converting enzyme 2 (ACE2) interaction induces large-scale allosteric changes across spike (S) protein.

Figure 4.

(A) Differences in deuterium exchange (ΔDex) (t = 1 min) in S protein upon binding ACE2 showing decreased (blue) and increased (red) deuterium exchange, mapped onto the structure of S protein. Deuterium exchange differences (X-axis) for peptides from (B) receptor binding domain (RBD)S and S2 subunit (C). Peptides are grouped into clusters indicated by brackets (X-axis) for ease of display. Individual peptides within each cluster are identifiable from the source data (Figure 4—source data 1). Difference cutoff ±0.3 D (Houde et al., 2011) is the deuterium exchange significance threshold indicated by pink shaded box with standard error values in gray. Positive differences (>0.3 D) denote increased deuterium exchange, and negative differences (<−0.3 D) denote decreased deuterium exchange in S protein bound to ACE2. (B) Peptides spanning residues interacting with ACE2 are in purple. (C) Peptides spanning S1/S2 cleavage site, fusion peptide (FP) and heptad repeat 1 (HR1) are highlighted in pink boxes, while peptides spanning central helix and heptad repeat 2 (HR2) are in blue. (D) Stacked mass spectra with isotopic envelopes after deuterium exchange (t = 1, 10 min) for select peptides from (i) RBD (residues 476–498), (ii) S1/S2 cleavage site (residues 672–690), (iii) FP (residues 823–832), and (iv) HR2 (residues 1175–1188) are shown for the S protein and S:ACE2 complex. Mass spectra of the equivalent undeuterated peptide are shown for reference. The centroid masses are indicated by red arrowheads.

Figure 4—source data 1. Differences in deuterium exchange values between spike (S):angiotensin-converting enzyme 2 (ACE2) complex and free S protein at indicated labeling times.