Figure 5

Predicted functional sites superimposed onto representative tertiary structures of the Hmd enzyme and paralog. (A) Residues representing alignment positions in either Hmd enzymes (red) or paralogs (orange) with putative functional residues in at least 40% of models are superimposed onto the structures of the Hmd enzyme (blue) and paralog₁ (green) from M. jannaschii. These residues are D143, K151, H174, C176, T177, H201, C204, E207, K209, R235, and D251 in Hmd enzyme from M. janaschii and H55, E61, E91, N125, C127, T128, H155, K198, and D206 in Hmd paralog₁ from M. janaschii. (B) Five such residues from each protein are conserved between the Hmd enzymes and paralogs. (C) One cluster contains four such residues from each protein (H174, C176, T177, and H201 from Hmd enzyme and N125, C127, T128, and H154 from Hmd paralog₁). C176 is known to bind the iron atom and cofactor molecule that coordinate the enzymatic reaction of the Hmd enzyme [8, 9]. (D) A second region with no previously characterized functional contribution contains one such residue from each protein (D143 in Hmd enzyme and E94 in Hmd paralog₁). This figure shows a predicted functional similarity between Hmd enzymes and paralogs and also identifies a putative novel site of common function.