6f05
ARABIDOPSIS THALIANA GSTF9, GSO3 BOUND
Structural highlights
Function[GSTF9_ARATH] In vitro, possesses glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene (CDNB) and benzyl isothiocyanate (BITC), and glutathione peroxidase activity toward cumene hydroperoxide and linoleic acid-13-hydroperoxide. May be involved in the conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles and have a detoxification role against certain herbicides.[1] [2] Publication Abstract from PubMedGlutathione transferase enzymes help plants to cope with biotic and abiotic stress. They mainly catalyze the conjugation of glutathione (GSH) onto xenobiotics, and some act as glutathione peroxidase. With X-ray crystallography, kinetics, and thermodynamics, we studied the impact of oxidation on Arabidopsis thaliana glutathione transferase Phi 9 (GSTF9). GSTF9 has no cysteine in its sequence, and it adopts a universal GST structural fold characterized by a typical conserved GSH-binding site (G-site) and a hydrophobic co-substrate-binding site (H-site). At elevated H2 O2 concentrations, methionine sulfur oxidation decreases its transferase activity. This oxidation increases the flexibility of the H-site loop, which is reflected in lower activities for hydrophobic substrates. Determination of the transition state thermodynamic parameters shows that upon oxidation an increased enthalpic penalty is counterbalanced by a more favorable entropic contribution. All in all, to guarantee functionality under oxidative stress conditions, GSTF9 employs a thermodynamic and structural compensatory mechanism and becomes substrate of methionine sulfoxide reductases, making it a redox-regulated enzyme. Redox-regulated methionine oxidation of Arabidopsis thaliana glutathione transferase Phi9 induces H-site flexibility.,Tossounian MA, Wahni K, Van Molle I, Vertommen D, Astolfi Rosado L, Messens J Protein Sci. 2018 May 7. doi: 10.1002/pro.3440. PMID:29732642[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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