Extended Data Figure 7: Residues that mediate BtuB–OmpF and BtuB–BtuB interactions in molecular dynamics simulations.

a, b, Residues that mediate BtuB–OmpF (a) and BtuB–BtuB (b) interactions. The interaction matrix charts the frequency of interaction between any pair of BtuB and OmpF residues, as a proportion of the total number of interactions that occurred, from high proportional frequency (dark green) to low (white). Depicted here is a subset of the entire interaction matrix, showing only the residues which engaged in interactions with the other protein over a threshold value; any BtuB residue which had a proportional interaction frequency of more than 1 × 10⁻³ with any OmpF residue is shown, and similarly for any OmpF residue. On each side, residues with interaction frequency values above approximately one-third of the maximum value of interaction are highlighted in bold. The bar plots show the proportional interaction frequencies of each single BtuB (side) and OmpF (top) residue, for the subset of residues that are shown in the interaction matrix. See Methods for a full mathematical explanation of the interaction value calculations. Bar plots are coloured according to the bar values, from high proportional interaction frequency (dark red) to low (white). This is consistent with the colour scheme in Fig. 4e. Note the matrix in b is symmetric.