Structure of Urocanate Hydratase from the protozoan Trypanosoma cruzi

The enzyme Urocanate Hydratase (UH) participates in the catabolic pathway of L-histidine. Trypanosoma cruzi Urocanate Hydratase (TcUH) is identified as a therapeutic molecular target in the WHO/TDR Targets Database. We report the 3D structure determination and number of features of TcUH, and compared it to other few available bacterial UH structures. Each monomer presents two domains and one NAD+ molecule. Superpositions revealed differences in the relative orientation of domains within monomers, such that TcUH monomer A resembles Urocanate Hydratase from Geobacillus kaustophilus (GkUH) (open conformation), while monomer C resembles Urocanate Hydratase from Pseudomonas putida (PpUH) and Urocanate Hydratase from Bacillus subtilis (BsUH) (closed conformations). We use the structure of TcUH to make considerations about 3 non-deleterious and 2 deleterious mutations found in human UHs: non-deleterious mutations could be accommodated without large displacements or interaction interruptions, whereas deleterious mutations in one case might disrupt an α-helix (as previously suggested) and in the other case, besides disrupting the enzyme interaction with the substrate, might interfere with interdomain movement. •TcUH is the first UH from eukaryotes to have its structure solved.•Each TcUH monomer has two domains and one NAD+ molecule.•Crystal structure reveals different conformations of monomers.•Different monomer conformations should reflect protein dynamics in catalysis.•Inferences to human UH deleterious and non-deleterious mutants could be made.