Figure 1.

Crystal structure of PA1994 from P. aeruginosa. (a) Stereo ribbon diagram of the PA1994 monomer color coded from the N-terminus (blue) to the C-terminus (red). Helices (H1–H2) and β-strands (β1–β15) are indicated. (b) Ribbon representation of the PA1994 dimer showing domain swapping of the N-terminal β-strands. Monomers are depicted in blue and magenta. (c) Diagram showing the secondary-structure elements of PA1994 superimposed on its primary sequence. The labeling of secondary-structure elements is in accord with PDBsum (http://www.ebi.ac.uk/pdbsum), where α-helices are sequentially labeled (H1, H2, H3 etc.), β-strands are labeled (A, B, C etc.) according to the β-sheets to which they are assigned, β-turns and γ-turns are designated by Greek letters (β, γ) and β-hairpins are designated by red loops. For PA1994, the α-helix (H2), 3₁₀-helix (H1), β-strands in β-sheets (A–C), β-turns (β) and β-hairpins are indicated.