Fig. 2.

Evolutionary couplings give residue pairs that are hydrogen bonded. From the evolutionary couplings (ECs) (black) predicted between residues (red) on strands 5 and 6 of EstA (Left), a subset of hydrogen-bonded pairs (dashed lines, where N–O distance ≤ 3.4 Å) is extracted. Predicted adjacent β-strands are shifted plus or minus three residues relative to each other to generate alternate configurations of residue pairs (Center). To select the best configuration, the EC strength of all pairs is summed and the highest-scoring configuration is selected; then distance constraints are applied to N–O atoms of alternate residue pairs (Right) to reflect N–H ... O = C hydrogen bonds.