Fig. 1: PopA is a divergent OMP Pentamer.
From: A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily
A Ribbon diagram of the PopA pentamer. B Two views highlighting the wall-reinforcing alpha helix of loop 2 (pale yellow), plug (pink) and oligomerisation loop 8 (green, forms centre of structure shown in panel A). C Electrostatic representation of PopA pentamer faces (extracellular left, periplasmic right). D Aromatic girdle residues (blue sticks), and inferred membrane spacing. E Lysine ring (purple sticks) at extracellular face. F Hydrophobic span (white) of PopA transmembrane β-strands. G Monomers make a continuous outer sheet wall via seams (backbone shown in stickform) H, I Residue sidechain detail for loop 8 and central chamber. J Oligomer comparison (overlay, centre) of PopA (blue, left) to trimeric anion transporter (1E5414, red, right), demonstrating arrangement around different loops (coloured individually, strand β16 of both is purple to provide a barrel orientation guide).
