Cartoon representation of the EschOTU crystal structure colored in a rainbow gradient from N- to C-terminus. The catalytic triad residues are marked on both the structure and the linear color gradient above, showing their positions with respect to each other and the overall OTU sequence. The black and grey arrows relate how the EschOTU fold is permutated with respect to other OTUs. The black open arrow marks the open N- and C-termini, while the closed grey arrow marks a closed loop. OTU subfamilies that follow this overall sequence topology are listed in the lower right. This arrangement is only observed in EschOTU. 