Figure 5. Conversion from prepore to pore.

a, Superimposition of domains 2c of the PA pore and prepore (monomer; PDB ID: 3TEW). Loops undergoing dramatic conformational changes during the prepore to pore conversion are labeled (blue). b, Overview of the three layers of conformational changes during the conversion. The interaction between the 2β₉–2β₁₀ loop and the β sheet (blue box) is shown in panel e. c, Superimposition of the PA pore (pink, orange, and blue; colored by domain) and prepore (light green; PDB ID: 1TZO). Domains 4 and 2s are removed for clarity. Between the two structures, domain 2c has a Cα rmsd=6.87 Å, whereas domains 1' and 3 remain unchanged with Cα rmsd=0.54 Å and 0.58 Å, respectively. d, Illustration of the steps of conformational changes during the prepore to pore conversion. For simplicity, only two protomers are illustrated. e, Interface between the 2β₉–2β₁₀ loop (green) and the bent β sheet (gold) of 2β₁₂, 2β₆, and 2β₇ of the adjacent protomer in the PA pore. Hydrogen bonds between the backbone of the loop and the side chains of the β sheet are depicted with dashed lines.