8ETN

The X-ray Crystal Structure of Tri-Ketone Dioxygenase from Rice

Summary for 8ETN

• Entry DOI: 10.2210/pdb8etn/pdb
• Descriptor: Tri-Ketone Dioxygenase (1 entity in total)
• Functional Keywords: tri-ketone dioxygenase, rice, oryza sativa, oxidoreductase
• Biological source: Oryza sativa (Asian cultivated rice)
• Total number of polymer chains: 4
• Total formula weight: 166531.75

Authors

Rydel, T.J.,Duda, D.,Zheng, M.,Duff, S.M.G. (deposition date: 2022-10-17, release date: 2023-12-06, Last modification date: 2024-10-16)

Primary citation

Duff, S.M.G.,Zhang, M.,Zinnel, F.,Rydel, T.,Taylor, C.M.,Chen, D.,Tilton, G.,Mamanella, P.,Duda, D.,Wang, Y.,Xiang, B.,Karunanandaa, B.,Varagona, R.,Chittoor, J.,Qi, Q.,Hall, E.,Garvey, G.,Zeng, J.,Zhang, J.,Li, X.,White, T.,Jerga, A.,Haas, J.
Structural and functional characterization of triketone dioxygenase from Oryza Sativa.
Biochim Biophys Acta Gen Subj, 1868:130504-130504, 2023

PubMed Abstract: The transgenic expression of rice triketone dioxygenase (TDO; also known as HIS1) can provide protection from triketone herbicides to susceptible dicot crops such as soybean. Triketones are phytotoxic inhibitors of plant hydroxyphenylpyruvate dioxygenases (HPPD). The TDO gene codes for an iron/2-oxoglutarate-dependent oxidoreductase. We obtained an X-ray crystal structure of TDO using SeMet-SAD phasing to 3.16 Å resolution. The structure reveals that TDO possesses a fold like that of Arabidopsis thaliana 2-oxoglutarate‑iron-dependent oxygenase anthocyanidin synthase (ANS). Unlike ANS, this TDO structure lacks bound metals or cofactors, and we propose this is because the disordered flexible loop over the active site is sterically constrained from folding properly in the crystal lattice. A combination of mass spectrometry, nuclear magnetic resonance, and enzyme activity studies indicate that rice TDO oxidizes mesotrione in a series of steps; first producing 5-hydroxy-mesotrione and then oxy-mesotrione. Evidence suggests that 5-hydroxy-mesotrione is a much weaker inhibitor of HPPD than mesotrione, and oxy-mesotrione has virtually no inhibitory activity. Of the close homologues which have been tested, only corn and rice TDO have enzymatic activity and the ability to protect plants from mesotrione. Correlating sequence and structure has identified four amino acids necessary for TDO activity. Introducing these four amino acids imparts activity to a mesotrione-inactive TDO-like protein from sorghum, which may expand triketone herbicide resistance in new crop species.

PubMed: 37967728
DOI: 10.1016/j.bbagen.2023.130504

Experimental method

X-RAY DIFFRACTION (3.16 Å)