Structural highlights
FunctionDAO_ORYSI 2-oxoglutarate-dependent dioxygenase essential for auxin catabolism and maintenance of auxin homeostasis in reproductive organs. Catalyzes the irreversible oxidation of indole-3-acetic acid (IAA) to the biologically inactive 2-oxoindole-3-acetic acid (OxIAA) (By similarity). Publication Abstract from PubMedAllosteric regulation is protein activation by effector binding at a site other than the active site. Here, we show via X-ray structural analysis of gibberellin 2-oxidase 3 (GA2ox3), and auxin dioxygenase (DAO), that such a mechanism maintains hormonal homeostasis in plants. Both enzymes form multimers by interacting via GA4 and indole-3-acetic acid (IAA) at their binding interface. Via further functional analyses we reveal that multimerization of these enzymes gradually proceeds with increasing GA4 and IAA concentrations; multimerized enzymes have higher specific activities than monomer forms, a system that should favour the maintenance of homeostasis for these phytohormones. Molecular dynamic analysis suggests a possible mechanism underlying increased GA2ox3 activity by multimerization-GA4 in the interface of oligomerized GA2ox3s may be able to enter the active site with a low energy barrier. In summary, homeostatic systems for maintaining GA and IAA levels, based on a common allosteric mechanism, appear to have developed independently. A common allosteric mechanism regulates homeostatic inactivation of auxin and gibberellin.,Takehara S, Sakuraba S, Mikami B, Yoshida H, Yoshimura H, Itoh A, Endo M, Watanabe N, Nagae T, Matsuoka M, Ueguchi-Tanaka M Nat Commun. 2020 May 1;11(1):2143. doi: 10.1038/s41467-020-16068-0. PMID:32358569[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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