Structure of Y. pestis RipC. (a) Stereoview of monomeric RipC depicting the TIM barrel, in which the α-helices, β-strands and loops are colored blue, cyan and gray, respectively. Missing residues within the TIM-barrel domain, including α-helix 1 (indicated by a red arrow), are represented as dotted lines, whereas the C-terminal domain is represented as a gray oval. (b) Trimeric RipC with a homology model of the C-terminal unstructured domain based on the I-Tasser composite model (Roy et al., 2010), in which the predicted topology of the C-terminal domains is circled and shaded and is located close to the top of the TIM barrel of an adjacent monomer. Monomers are colored blue, red and green. (c) The size-exclusion chromatogram reveals trimeric RipC (blue trace) based on protein calibration standards (black dashed trace; labelled in kDa).