Comparison between PDB entries 4bl4 and 1w33. (a) Cartoon representation of the structure of the CspA dimer found in PDB entry 1w33. (b) Superposition (r.m.s.d. = 0.138 Å) of C-terminal residues 230–250 from chain A in 4bl4 (red) and 1w33 (blue) shown as a cartoon against chain B rendered as a surface (grey). (c) Cartoon representation of the structures of both copies of the CspA dimer found in the asymmetric unit of PDB entry 4bl4. The dimer formed by chains C and D (grey) has been superimposed on that formed by chains A and B (red) using secondary-structure matching (Krissinel & Henrick, 2007), with an r.m.s.d. of 0.264 Å. (d) Subunits from 1w33 (blue) and 4bl4 (red) superposed, showing the deflection of helix F between residues 225 and 227 (shown in yellow). (e) Overlay of the dimer assemblies found in 1w33 and 4bl4, showing the difference in the intermonomer angle. Chains A from 1w33 (grey) and 4bl4 (red) were superposed using secondary-structure matching over residues 70–220. The average r.m.s.d. of superposition of each chain in 1w33 onto each chain in 4bl4 over this residue range is 0.539 Å. (f) Superposition of C-terminal residues from chain A of 1w33 and 4bl4, showing an average increase in intermonomer angle of 16.8° averaged over both copies of the dimer in the 4bl4 asymmetric unit (the individual angles for the AB and CD dimers are 16.96 and 16.66°, respectively). This figure was generated using PyMOL (Schrödinger LLC).