3D structure prediction of HydH5. Top of panels A, B and C are the predicted 3D structure of the corresponding three HydH5 domains. The structure models were generated by the MODELLER program and the cartoon representation of the structure models was prepared using Pymol (http://www.pymol.org/). Secondary structure elements and conserved catalytic residues are labelled. Bottom panels A, B and C plot the sequence alignments between three HydH5 domains and their corresponding templates. The template identification and sequence alignments were generated by the HHpred server. The probabilities of remote homologous relationship for each alignment provided by HHpred are 0.996, 0.993 and 0.996, although the sequence identities of the three alignments are only 17%, 14% and 22% respectively. Conserved residues between the three HydH5 domains and their templates are labeled by colons under the alignment if they share similar side chains, and with asterisks if identical residues. Position of α-helix and β-sheet in each domain of Hyd5 is indicated by cylinder and arrow, respectively.