Fig. 2.

Structure of DING proteins. a Cartoon representation of the structure of a DING protein representative: HPBP solved at 1.9 Å [23]. HPBP possess an elongated fold composed of two adjacent globular domains (in dark blue and cyan). Each domain is constituted by a central β-sheet core flanked by α-helices and contains a disulphide bridge (orange sticks). Interconnected by an antiparallel two-stranded β-sheet acting as a hinge (in yellow), the two domains form a deep cleft wherein is bound a phosphate molecule (red balls). b Structural comparison of different known phosphate-SBPs: HPBP is shown in cyan, PfluDING is shown in yellow, E. coli PstS protein is shown in red. The four protruding DING protein-specific loops are indicated by black arrows. c Phosphate-binding site of DING proteins. Residues involved in the binding of the phosphate molecule are labelled. The 12 H-bonds between the protein and the phosphate molecule are represented in dashed lines. Side chains are shown in sticks and main chain is represented in cartoon mode. Surface is computed from the protein Van der Waals surfaces