Fig. 4: Open and closed structure of the tripartite tricarboxylate transporter—solute binding protein TphC.

A Crystal structure of TphC is shown in ribbon representation (α-helices red, β-strands green), the structure is comprised of two domains with a large solvent accessible cleft located at the domain interface. A surface representation of the protein has been cut away to highlight the substrate-binding pocket. B Upon TPA binding (CPK sphere representation, all atom colours) the two domains reorientate to enclose the bound TPA. The cut away surface representation highlights the occluded pocket in which the TPA is bound.