Fig. 2
From: A viral-fusion-peptide-like molecular switch drives membrane insertion of botulinum neurotoxin A1
Crystal structure of tHNA at an acidic pH. a Structure of a tHNA dimer (orange and green) observed in an asymmetric unit. The BoNT-switch of chain A is colored in magenta. b The structures of the BoNT-switch at neutral (left) and acidic pH (right). The β2/β3 loop is highlighted in green. Residues discussed in the text are shown as sticks, Cα atoms of conserved glycines are drawn in spheres. (Boxed) Sequence alignment of the β2/β3 loop and the internal fusion loops of Ebola virus (EBOV) and Marburg virus (MARV) glycoproteins were generated with ESPript 3.0. c Amino acid sequences of E620-F667 (BoNT/A1 numbering) from 42 BoNT subtypes8, TeNT, BoNT/X, and eBoNT/J were aligned (Clustal Omega) and depicted as sequence logo. Individual sequences are shown in Supplementary Fig. 6. The secondary structure of the BoNT/A1-switch at neutral and acidic pH is shown on the top. The β2/β3 loop is underlined in green. The solvent-accessible surface area (SASA) of the corresponding residues is shown at the bottom. SASA was calculated using the program POPS42. The SASA values are for the entire residue and represent fraction of exposed surface area
