Fig. 1:

Sculpting β-barrel geometry. A. Pore diameter can be controlled through the number of β-strands in the β-barrel blueprint. B. β-barrel 2D interaction map. Strong bends in the β-strands (< 90° bend, right) is achieved by stacking several glycine kink residues (yellow spheres) along the β-barrel axis, as opposed to placing one kink (>90° bend, left). C-D. Cross-sections of explicitly assembled β-barrel backbones without (cylinder, C) and with (D) glycine kinks. The Cβ atoms of the residues facing the pore are shown as sphere’s and colored based on their respective repulsion energy. Glycine kinks positions are shown with arrows; placement at the corners of the embedded rectangular, oval and triangular shapes (dashed lines in D) generates the desired backbone geometries. E. Polar threonine residues are tolerated on the membrane-exposed surface of TMBs (right) as they can form a hydrogen bond to the backbone, mimicking the interactions with water molecules observed in similarly curved areas of water-exposed β-strands (left).