Fig. 1

The structure of the UpaB functional α-domain (α^UpaB). a Domain organisation of UpaB comprising an N-terminal signal sequence (SP; residues 1–37), an α-domain (α^UpaB; residues 38–500) and a β-domain (β^UpaB; residues 501–776). b Analytical ultracentrifugation sedimentation velocity analysis of α^UpaB. The continuous standardised sedimentation distribution [c(s)] shows that UpaB at 2.2 mg ml⁻¹ exists as a 3.1 s_20,w monomer. c Cartoon representation of the α^UpaB structure, including d top view. The central domain consisting of extended β-strands is shown in dark green. The N-terminal and C-terminal β-helical domains are shown in yellow and light green, respectively. The top view has F1, F2 and F3 faces shown. e Stereo view of the 2F_o−F_c electron density map contoured at 1σ of the cross-section of the α^UpaB β-helix. Structural comparison of UpaB (green) with the α-domain of f pertactin (from B. pertussis; magenta; PDB 1DAB) and g Ag43a (from UPEC; blue; PDB 4KH3)