Intradiol ring-cleavage dioxygenase Tetur07g05930 originating from major agricultural pest Tetranychus urticae is...

In the environment, aromatic compounds are commonly introduced artificially or as natural plant secondary metabolites. A major agricultural pest, Tetranychus urticae, has acquired genes encoding for intradiol ring-cleavage dioxygenases (IDRCDs) that can detoxify such compounds. Studies of one such IDRCD, TuIDRCD930 (encoded by gene tetur07g05930), revealed a dimerization not seen before in enzymes of this class in T. urticae, including a different oligomerization mechanism observed in fungal and bacterial homologs. Through SEC-SAXS and gel filtration experiments, TuIDRCD930 was found to dimerize by utilizing two different interactions in the N-termini: changes in protonation states and the formation of a disulfide bond. Additionally, in vitro studies demonstrate catalytic efficiency of TuIDRCD930 towards polycyclic aromatic compounds, which represents an evolutionary advantage for T. urticae. It was shown that the dimerization process does not obscure access of relatively large substrates to the enzyme active site. We further displayed that the recombinant version of TuIDRCD930 is active in both monomeric and dimeric states. Overall, this work determines oligomerization and activity not previously described in IDRCDs from T. urticae and provides further evidence of how evolution has provided this pest with novel tools to overcome plant defenses.