Publications

• 4-hydroxyphenylpyruvate dioxygenase catalysis: identification of catalytic residues and production of a hydroxylated intermediate shared with a structurally unrelated enzyme.

  Raspail C., Graindorge M., Moreau Y., Crouzy S., Lefebvre B., Robin A.Y., Dumas R., Matringe M.

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) catalyzes the conversion of 4-hydroxyphenylpyruvate (HPP) into homogentisate. HPPD is the molecular target of very effective synthetic herbicides. HPPD inhibitors may also be useful in treating life-threatening tyrosinemia type I and are currently in tria ... >> More

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) catalyzes the conversion of 4-hydroxyphenylpyruvate (HPP) into homogentisate. HPPD is the molecular target of very effective synthetic herbicides. HPPD inhibitors may also be useful in treating life-threatening tyrosinemia type I and are currently in trials for treatment of Parkinson disease. The reaction mechanism of this key enzyme in both plants and animals has not yet been fully elucidated. In this study, using site-directed mutagenesis supported by quantum mechanical/molecular mechanical theoretical calculations, we investigated the role of catalytic residues potentially interacting with the substrate/intermediates. These results highlight the following: (i) the central role of Gln-272, Gln-286, and Gln-358 in HPP binding and the first nucleophilic attack; (ii) the important movement of the aromatic ring of HPP during the reaction, and (iii) the key role played by Asn-261 and Ser-246 in C1 hydroxylation and the final ortho-rearrangement steps (numbering according to the Arabidopsis HPPD crystal structure 1SQD). Furthermore, this study reveals that the last step of the catalytic reaction, the 1,2 shift of the acetate side chain, which was believed to be unique to the HPPD activity, is also catalyzed by a structurally unrelated enzyme. << Less

  J Biol Chem 286:26061-26070(2011) [PubMed] [EuropePMC]

• Studies on a possible reaction intermediate of p-hydroxyphenylpyruvate dioxygenase.

  Nakai C., Nozaki M., Hayaishi O.

  Biochem Biophys Res Commun 67:590-595(1975) [PubMed] [EuropePMC]

• The C-terminal of rat 4-hydroxyphenylpyruvate dioxygenase is indispensable for enzyme activity.

  Lee M.H., Zhang Z.H., MacKinnon C.H., Baldwin J.E., Crouch N.P.

  We have cloned and overexpressed rat 4-hydroxyphenylpyruvate dioxygenase (4HPPD) in Escherichia coli. The soluble, active recombinant enzyme was shown to contain both 4HPPD and alpha-ketoisocaproate dioxygenase (alpha KICD) activity. However, upon truncation of the 14 amino acids at the C-terminus ... >> More

  We have cloned and overexpressed rat 4-hydroxyphenylpyruvate dioxygenase (4HPPD) in Escherichia coli. The soluble, active recombinant enzyme was shown to contain both 4HPPD and alpha-ketoisocaproate dioxygenase (alpha KICD) activity. However, upon truncation of the 14 amino acids at the C-terminus by site-directed mutagenesis, the resulting mutant enzyme (rat F antigen) exhibited complete loss of 4HPPD and alpha KICD activities. This finding suggests that the C-terminal extension domain plays an essential role in the catalytic activity of the enzyme. << Less

  FEBS Lett. 393:269-272(1996) [PubMed] [EuropePMC]

• Steady state kinetics of 4-hydroxyphenylpyruvate dioxygenase from human liver (III).

  Rundgren M.

  Kinetic experiments have been made with an apparently homogenous preparation of human liver 4-hydroxyphenylpyruvate dioxygenase Form 3 (4-hydroxyphenylpyruvate: oxygen oxidoreductase (hydroxylating, decarboxylating), EC 1.13.11.27) at 37 degrees in 0.2 M Tris/HCL, pH 7.5, by measuring the evolved ... >> More

  Kinetic experiments have been made with an apparently homogenous preparation of human liver 4-hydroxyphenylpyruvate dioxygenase Form 3 (4-hydroxyphenylpyruvate: oxygen oxidoreductase (hydroxylating, decarboxylating), EC 1.13.11.27) at 37 degrees in 0.2 M Tris/HCL, pH 7.5, by measuring the evolved carbon dioxide from the 1-14C-labeled substrate or the formation of homogentisate from the U-14C-labeled substrate. The effect of variations in the concentrations of substrates, products, and metal chelators on the velocity of the forward reaction was studied. The results agree with an Ordered Bi Bi kinetic mechanism (Cleland, W. W. (1963) Biochim. Biophys. Acta 67, 104--137), where 4-hydroxyphenylpyruvate is added prior to oxygen and CO2 released before homogentisate. A Theorell-Chance mechanism has not been excluded. << Less

  J Biol Chem 252:5094-5099(1977) [PubMed] [EuropePMC]

• Purification and properties of hog liver 4-hydroxyphenylpyruvate dioxygenase.

  Roche P.A., Moorehead T.J., Hamilton G.A.

  Arch Biochem Biophys 216:62-73(1982) [PubMed] [EuropePMC]

• Intermediate partitioning kinetic isotope effects for the NIH shift of 4-hydroxyphenylpyruvate dioxygenase and the hydroxylation reaction of hydroxymandelate synthase reveal mechanistic complexity.

  Shah D.D., Conrad J.A., Moran G.R.

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) and hydroxymandelate synthase (HMS) are similar enzymes that catalyze complex dioxygenation reactions using the substrates 4-hydroxyphenylpyruvate (HPP) and dioxygen. Both enzymes decarboxylate HPP and then hydroxylate the resulting hydroxyphenylacetate ( ... >> More

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) and hydroxymandelate synthase (HMS) are similar enzymes that catalyze complex dioxygenation reactions using the substrates 4-hydroxyphenylpyruvate (HPP) and dioxygen. Both enzymes decarboxylate HPP and then hydroxylate the resulting hydroxyphenylacetate (HPA). The hydroxylation reaction catalyzed by HPPD displaces the aceto substituent of HPA in a 1,2-shift to form 2,5-dihydroxyphenylacetate (homogentisate, HG), whereas the hydroxylation reaction of HMS places a hydroxyl on the benzylic carbon forming 3'-hydroxyphenylacetate (S-hydroxymandelate, HMA) without ensuing chemistry. The wild-type form of HPPD and variants of both enzymes uncouple to form both native and non-native products. We have used intermediate partitioning to probe bifurcating steps that form these products by substituting deuteriums for protiums at the benzylic position of the HPP substrate. These substitutions result in altered ratios of products that can be used to calculate kinetic isotope effects (KIE) for the formation of a specific product. For HPPD, secondary normal KIEs indicate that cleavage of the bond in the displacement reaction prior to the shift occurs by a homolytic mechanism. NMR analysis of HG derived from HPPD reacting with enantiomerically pure R-3'-deutero-HPP indicates that no rotation about the bond to the radical occurs, suggesting that collapse of the biradical intermediate is rapid. The production of HMA was observed in HMS and HPPD variant reactions. HMS hydroxylates to form exclusively S-hydroxymandelate. When HMS is reacted with R-3'-deutero-HPP, the observed kinetic isotope effect represents geometry changes in the initial transition state for the nonabstracted proton. These data show evidence of sp(3) hybridization in a HPPD variant and sp(2) hybridization in HMS variants, suggesting that HMS stabilizes a more advanced transition state in order to catalyze H-atom abstraction. << Less

  Biochemistry 52:6097-6107(2013) [PubMed] [EuropePMC]

• Blue color, metal content, and substrate binding in 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. strain P. J. 874.

  Lindstedt S., Rundgren M.

  Purified preparations of 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. strain P. J. 874 are blue, epsilon 595-850 approximately 2.6 +/-0.5 (n = 6) mM-1 cm-1. Iron and zinc were the only metals detected by x-ray fluorescence of an enzyme preparation and the mean content in different prep ... >> More

  Purified preparations of 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. strain P. J. 874 are blue, epsilon 595-850 approximately 2.6 +/-0.5 (n = 6) mM-1 cm-1. Iron and zinc were the only metals detected by x-ray fluorescence of an enzyme preparation and the mean content in different preparation as determined by atomic absorption spectroscopy was determined by atomic absorption spectroscopy was 0.95 +/- 0.17 (n = 6) and 0.68 +/-0.27 (n = 7) mol/mol 150-kilodalton tetramer, respectively. It is yet unclear if zinc is a contaminant or may be given a structural role. Results with iron chelators and reductants showed that the 595-nm absorbance is linked to enzyme-bound Fe3+ and that reduction of iron, which occurs concomitantly with disappearance of the color, is required for enzyme activity. The enol tautomer of 4-hydroxyphenylpyruvate appeared to form 2:1 a complex with enzyme-bound Fe3+, which may be the cause of the long known substrate inhibition of the enzyme. Iron chelation also seemed to be involved in the inhibition by other substrate analogues, i.e. substituted catechols and those with one phenolic hydroxyl group in ortho position to short carboxylic acid side chains. Together, substrate analogue, pH, and modification studies indicated that the tautomerizable keto group with a double bond in 3-4 position favors productive substrate binding to Fe2+ and a base with a pK alpha of approximately 6.4. << Less

  J Biol Chem 257:11922-11931(1982) [PubMed] [EuropePMC]

• Evidence for the mechanism of hydroxylation by 4-hydroxyphenylpyruvate dioxygenase and hydroxymandelate synthase from intermediate partitioning in active site variants.

  Shah D.D., Conrad J.A., Heinz B., Brownlee J.M., Moran G.R.

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) and hydroxymandelate synthase (HMS) each catalyze similar complex dioxygenation reactions using the substrates 4-hydroxyphenylpyruvate (HPP) and dioxygen. The reactions differ in that HPPD hydroxylates at the ring C1 and HMS at the benzylic position. The ... >> More

  4-Hydroxyphenylpyruvate dioxygenase (HPPD) and hydroxymandelate synthase (HMS) each catalyze similar complex dioxygenation reactions using the substrates 4-hydroxyphenylpyruvate (HPP) and dioxygen. The reactions differ in that HPPD hydroxylates at the ring C1 and HMS at the benzylic position. The HPPD reaction is more complex in that hydroxylation at C1 instigates a 1,2-shift of an aceto substituent. Despite that multiple intermediates have been observed to accumulate in single turnover reactions of both enzymes, neither enzyme exhibits significant accumulation of the hydroxylating intermediate. In this study we employ a product analysis method based on the extents of intermediate partitioning with HPP deuterium substitutions to measure the kinetic isotope effects for hydroxylation. These data suggest that, when forming the native product homogentisate, the wild-type form of HPPD produces a ring epoxide as the immediate product of hydroxylation but that the variant HPPDs tended to also show the intermediacy of a benzylic cation for this step. Similarly, the kinetic isotope effects for the other major product observed, quinolacetic acid, showed that either pathway is possible. HMS variants show small normal kinetic isotope effects that indicate displacement of the deuteron in the hydroxylation step. The relatively small magnitude of this value argues best for a hydrogen atom abstraction/rebound mechanism. These data are the first definitive evidence for the nature of the hydroxylation reactions of HPPD and HMS. << Less

  Biochemistry 50:7694-7704(2011) [PubMed] [EuropePMC]