Fig. 2. Structural conservation of the Igni18-like core-domain within MβLs with specialized activities.

The homolog structures 3X2Z from Thermotoga maritima, 4QN9 from Homo sapiens, 3BV6 from Vibrio cholerae, 2WYM from Escherichia coli, 6BRM from Pectobacterium carotovorum, 5HAA from Methanolobus psycrophilus, 4JO0 from Streptomyces venezuelae, 2XR1 from Methanosarcina mazei, and 4GCW from Bacillus subtilis are shown. Igni18 is depicted in purple and its two Zn²⁺ ions in orange. Enzymatic function, PDB code, source organism, metal ions bound, structural identity score (TM-score), and sequence identity [%] are indicated. The uncharacterized 3BV6 protein (2x Fe³⁺; TM-score 0.8418; seq. id. 21.1 %) is shown in violet together with UlaG (in green) due to their high similarity and because of the completeness of its structure as opposed to UlaG’s. The catalytic pockets and amino acids necessary for metal coordination are shown in a close-up. Structure overlays are sorted by overall structure similarity (TM-score, Supplementary Data S1).