Fig 2. Overall structure of the Hcp from A. baumannii.

(A) Cartoon representation of the Hcp structure whereby eight β-strands form a tight β-barrel, with one α-helix at one side, and an extended loop protruding more than 25 Å between strands 2 and 3. (B) Stick representation of the side-chain of hydrophobic residues forming the core of the β-barrel. (C) The Hcp hexameric ring. Cartoon representation of one hexamer generated by the 6-fold crystallographic symmetry. The α-helix of each monomer is placed almost parallel to the crystallographic axis. The diameter of the internal ring is 40 Å, while the external one is 80 Å. (D) Hexameric Hcp rings showing both, head-to-head (red-green) and head-to-tail (green-blue) packing.