4-Hydroxyphenylpyruvate dioxygenase

Moran, Graham R.

doi:10.1016/j.abb.2004.08.015

Cited by 251 publications

(223 citation statements)

References 102 publications

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“…1, 2 Deficiency in HPPD activity results in a rare hereditary metabolic disorder tyrosinemia type III, whereas HPPD inhibitors are used as medicines alleviating symptoms of other genetic inborn diseases related to accumulations of toxic metabolites produced in tyrosine catabolism. 3 In plants, the tyrosine metabolic pathway branches at HG for the biosynthesis of lyophilic cofactors required for photosynthesis, 4 and hence, HPPD inhibitors have herbicidal activity. 3 …”

Section: Introductionmentioning

confidence: 99%

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Role of Substrate Positioning in the Catalytic Reaction of 4-Hydroxyphenylpyruvate Dioxygenase—A QM/MM Study

et al. 2014

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Ring hydroxylation and coupled rearrangement reactions catalyzed by 4-hydroxyphenylpyruvate dioxygenase were studied with the QM/MM method ONIOM(B3LYP:AMBER). For electrophilic attack of the ferryl species on the aromatic ring, five channels were considered: attacks on the three ring atoms closest to the oxo ligand (C1, C2, C6) and insertion of oxygen across two bonds formed by them (C1-C2, C1-C6). For the subsequent migration of the carboxymethyl substituent, two possible directions were tested (C1→C2, C1→C6) and two different mechanisms were sought (step-wise radical, single-step heterolytic). In addition, formation of an epoxide (side)product and benzylic hydroxylation, as catalyzed by the closely related hydroxymandelate synthase, were investigated. From the computed reaction free energy profiles it follows that the most likely mechanism of 4-hydroxyphenylpyruvate dioxygenase involves electrophilic attack on the C1 carbon of the ring and subsequent singlestep heterolytic migration of the substituent. Computed values of the kinetic isotope effect for this step are inverse, consistent with available experimental data. Electronic structure arguments for the preferred mechanism of attack on the ring are also presented.

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Section: Introductionmentioning

confidence: 99%

“…3 In plants, the tyrosine metabolic pathway branches at HG for the biosynthesis of lyophilic cofactors required for photosynthesis, 4 and hence, HPPD inhibitors have herbicidal activity. 3 …”

Section: Introductionmentioning

confidence: 99%

Role of Substrate Positioning in the Catalytic Reaction of 4-Hydroxyphenylpyruvate Dioxygenase—A QM/MM Study

et al. 2014

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“…These two branches, which are otherwise quite separate, lead to different sets of products. The Phe branch leads, via cinnamate and p-coumarate, to benzoates, to soluble phenylpropanoids and, in higher plants, to lignin; the Tyr branch leads, via homogentisate, to plastoquinones and tocopherols or to degradation of the aromatic ring (Moran, 2005;Vogt, 2010). The AAH short circuit potentially confers three unique features on aromatic metabolism.…”

Section: Plant Aah: a Short Circuit Between Two Major Branches Of Aromentioning

confidence: 99%

Nonflowering Plants Possess a Unique Folate-Dependent Phenylalanine Hydroxylase That Is Localized in Chloroplasts

et al. 2010

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Tetrahydropterin-dependent aromatic amino acid hydroxylases (AAHs) are known from animals and microbes but not plants. A survey of genomes and ESTs revealed AAH-like sequences in gymnosperms, mosses, and algae. Analysis of fulllength AAH cDNAs from Pinus taeda, Physcomitrella patens, and Chlamydomonas reinhardtii indicated that the encoded proteins form a distinct clade within the AAH family. These proteins were shown to have Phe hydroxylase activity by functional complementation of an Escherichia coli Tyr auxotroph and by enzyme assays. The P. taeda and P. patens AAHs were specific for Phe, required iron, showed Michaelian kinetics, and were active as monomers. Uniquely, they preferred 10-formyltetrahydrofolate to any physiological tetrahydropterin as cofactor and, consistent with preferring a folate cofactor, retained activity in complementation tests with tetrahydropterin-depleted E. coli host strains. Targeting assays in Arabidopsis thaliana mesophyll protoplasts using green fluorescent protein fusions, and import assays with purified Pisum sativum chloroplasts, indicated chloroplastic localization. Targeting assays further indicated that pterin-4a-carbinolamine dehydratase, which regenerates the AAH cofactor, is also chloroplastic. Ablating the single AAH gene in P. patens caused accumulation of Phe and caffeic acid esters. These data show that nonflowering plants have functional plastidial AAHs, establish an unprecedented electron donor role for a folate, and uncover a novel link between folate and aromatic metabolism.

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“…Topramezone can be safely applied to maize at the 2-to 8-leaf growth stage, indicating no difference in selectivity, thus providing flexibility in application window (Gitsopoulos et al, 2010). This herbicide inhibits the activity of 4-hydroxyphenylpyruvate dioxygenase (4-HPPD, EC 1.13.11.27), an enzyme catalyzing the catabolism of the common to essentially all aerobic forms of life amino acid tyrosine (Moran, 2005). Inhibition of the activity of 4-HPPD disrupts the biosynthesis of carotenoid pigments in susceptible plants, thus resulting in bleaching (chlorophyll loss) of the foliage, cessation of growth, and ultimately death of the treated plants (Dayan et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Annual Grasses Control With Topramezone in Mixture With Als-Inhibiting Herbicides

Damalas

Gitsopoulos²,

Koutroubas

et al. 2015

Planta daninha

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Panicoid grasses are major weeds of maize and sugarcane as well as of several other important grains, including sorghum, pearl millet, and foxtail millet. Pot trials were conducted to study the activity and potential interactions of topramezone in mixture with recommended rates of rimsulfuron or nicosulfuron on three annual panicoid grasses (i.e. Echinochloa oryzoides,E.phyllopogon, and Panicum miliaceum). Target weeds were treated at the four- to five-leaf growth stage. On the basis of fresh weight reduction, topramezone alone provided 78% control of E.oryzoides, 68% control of E.phyllopogon, and 99% control of P.miliaceum. Topramezone plus rimsulfuron or nicosulfuron provided decreased control of both Echinochloa spp. compared with topramezone alone. The decreased control of E.oryzoidesand E.phyllopogon was more pronounced with rimsulfuron as a companion herbicide in the mixtures. Slightly decreased control of P.milaceum was observed with topramezone plus rimsulfuron compared with topramezone alone, but this was not the case for topramezone plus nicosulfuron. Increased topramezone rates mixed with rimsulfuron or nicosulfuron did not improve control of E.oryzoides and E.phyllopogon compared with the lowest topramezone rate. Also, increased topramezone rates mixed with rimsulfuron or nicosulfuron showed decreased control of both Echinochloa spp. when compared with either rimsulfuron or nicosulfuron alone, suggesting a two-way interaction between topramezone and the ALS-inhibiting herbicides. The above-mentioned interaction was not observed in P.miliaceum, probably related with species sensitivity to the herbicides tested. Newly introduced or naturalized panicoid grasses in maize fields may complicate selection of companion herbicides and rates for effective weed control.

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4-Hydroxyphenylpyruvate dioxygenase

Cited by 251 publications

References 102 publications

Role of Substrate Positioning in the Catalytic Reaction of 4-Hydroxyphenylpyruvate Dioxygenase—A QM/MM Study

Role of Substrate Positioning in the Catalytic Reaction of 4-Hydroxyphenylpyruvate Dioxygenase—A QM/MM Study

Nonflowering Plants Possess a Unique Folate-Dependent Phenylalanine Hydroxylase That Is Localized in Chloroplasts

Annual Grasses Control With Topramezone in Mixture With Als-Inhibiting Herbicides

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