Fig. 2: Pore and membrane features of PopA.
From: A porin-like protein used by bacterial predators defines a wider lipid-trapping superfamily
A Lefthand, ribbon diagram of FadL with plug (pink). Righthand, overlay of PopA plug (blue). B Lack of pore lumen in PopA, showing constriction of solvent-accessible volume (pink) as calculated using MOLE17. C Side-on and bottom views of PopA pentamer, demonstrative that the central chamber is located at the phospholipid/periplasmic side of the asymmetric outer membrane bilayer. D (side view), E (end-on) Spacefill of hydrophobic residues lining central chamber (from one monomer), using cutaway-view omitting one chain. F (from periplasm), G (in plane of membrane) Electron density and fit of alkyl chains in central chamber, with surrounding aromatic residues, 2fo-fc map at 1σ. H Fit of bound palmitate (white) under sidewall helix, 2fo-fc map at 1σ. The carboxylate of palmitate co-ordinates with Arg88 and the acyl chain sits in a cleft composed of several hydrophobic residues.
