Benzoate hydroxylase

Benzoate 1,2-hydroxylase (E.C. 1.13.99.2 - Benzoate, NADH oxygen, 1,2-oxidoreductase (decarboxylating). The intermediate diol has been isolated and labelling studies have verified that molecular oxygen is the source of the two hydroxyl groups 200). 

Benzoate 1,2-dioxygenase [EC 1.14.12.10], also called benzoate hydroxylase, catalyzes the reaction of benzoate with dioxygen and NADH to generate catechol, carbon dioxide, and NAD+. This is a multiprotein system which contains a reductase which is an iron-sulfur flavoprotein (FAD) and an iron-sulfur oxygenase. 

This enzyme [EC 1.14.13.2], also known as p-hydroxy-benzoate hydroxylase, catalyzes the reaction of 4-hydroxy-benzoate, NADPH, and dioxygen to produce proto-catechuate, NADP+, and water. FAD is used as a cofactor by this enzyme. The enzyme from Pseudomonas is very specific for the coenzyme substrate whereas 4-hy-droxybenzoate 3-monooxygenase (NAD(P)H) [EC... 

Double-hydroxylation reaction Non-heme iron NAD(P)H, FAD Benzoate hydroxylase 62)... 

Gatti DL, Palfey BA, Lah MS, Entsch B, Massey V, Ballou DP, Ludwig ML. The mobile flavin of 4-OH benzoate hydroxylase. Science 1994 266 110-114. 

Husain, M., B. Entsch, D.P. Ballou, V. Massey, and P.J Chapman. 1980. Fluoride elimination from substrates in hydroxylation reactions catalyzed by p-hydroxy-benzoate hydroxylase. /. Biol. Chem. 255 4189-4197. 

P-hydroxy benzoate hydroxylase b) 1.5 xl0-4MTPNH + 3.3 x 10-4M p-hydro-xybenzoate 213 213 ... 

Perhaps the most accurate calculations performed to date are the MP2, LMP2, and LCCSD(TO) calculations on chorismate mutase (CM) and para hydroxy-benzoate-hydroxylase (PHBH) (the L in the acronyms indicates that local approximations were used, and TO is an approximate triples correction).41,42 These are coupled-cluster calculations that account for the effects of conformational fluctuations through an averaging over multiple pathways (16 for CM and 10 for PHBH). Initial structures were sampled from semiempirical QM/MM dynamics, using B3LYP/MM optimized reaction pathways. 

YamaGUCHi, M., T. Yamauchi, and H. Fujisawa Studies on the Mechanism of Double Hydroxylation. I. Evidence for the Participation of NADH-Cytochrome c Reductase in the Reaction of Benzoate 1,2-Dioxygenase (Benzoate Hydroxylase). Biochem. Biophys. Res. Commun 67, 264 (1975). 

However, salicylic acid may be synthesized directly from benzoic acid by means of a benzoate hydroxylase enzyme system (Leon et al., 1993 Yalpani et al., 1993) see Chapter 8). The relative importance of these systems in higher plants is not known. 

Class A FPMOs Mechanism and Structure Para-hydroxy Benzoate Hydroxylase (PHBH)... 

Entsch, B., D. P. Ballou, and V. Massey The Role of Oxygenated Flavins in the Catalytic Reaction of p-Hydroxy-Benzoate Hydroxylase. In Flavins and Flavo-proteins (T. P. Singer, ed.). Amsterdam Elsevier, in press. 

Rhizobia. Taxa belonging to both the genera Rhizobium and Bradyrhizobium are capable of degrading simple aromatic compounds including benzoate (Chen et al. 1984) and 4-hydroxy-benzoate (Parke and Omston 1986 Parke et al. 1991). It has been shown that 4-hydroxyben-zoate hydroxylase is required for the transport of 4-hydroxybenzoate into the cell (Wong et al. 1994). In strains of Rhizobium trifolium, the metabolism of benzoate involves either 3,4-dihydroxybenzoate (protocatechuate) 3,4-dioxygenase (Chen et al. 1984), or catechol... 

Hydroxybenzoates can nndergo hydroxylation with or withont concomitant loss of CO2. For example, salicylate —> catechol + CO2 (salicylate-l-hydroxylase) (Fignre 3.9a) (White-Stevens et al. 1972) and 4-hydroxybenzoate —> 1,4-dihydroxybenzene + CO2 [(4-hydroxy-benzoate 1-hydroxylase (decarboxylating)] in Candida parapsilosis (Fignre 3.9b) (Eppink etal. 1997). 

Xun L, ER Sandvik (2000) Characterization of 4-hydroxyphenylactate 3-hydroxylase (HpaB) of Escherichia coli as a reduced flavin adenine dinucleotide-utilizing monooxygenase. Appl Environ Microbiol 66 481-486. Zaar A, J Gescher, W Eisenreich, A Bacher, G Fuchs (2004) New enzymes involved in aerobic benzoate metabolism m Azoarcus evansii. Mol Microbiol 54 223-238. 

MPTP) and sodium benzoate induce a strong downregulation in the expression of tyrosine hydroxylase mRNA and in the tyrosine hydroxylase-positive cells in the ventral diencephalon. These chemicals also decreased the expression of the dopamine transporter (DAT), a membrane transport protein involved in dopamine reuptake, that is, a specific marker of dopaminergic neurons [9]. 

Chen Q, Huang NN, Huang JT, Chen S, Fan J, Li C, Xie FK (2009) Sodium benzoate exposure downregulates the expression of tyrosine hydroxylase and dopamine transporter in dopaminergic neurons in developing zebrafish. Birth Defects Res B Dev Reprod Toxicol 86 85-91... 

Increases in substrate levels that were accidentally produced by metabolic engineering also resulted in an olfaction-detectable increase in the methyl benzoate emission in transgenic carnation [30]. The metabolic flux from the anthocy-anin pathway was redirected towards benzoic acid, the methyl ester precursor, by antisense suppression of the flavanone 3-hydroxylase. 

The dioxygenase nature of these reactions was first demonstrated by Kobayashi et al.201 with anthranilate 1,2-dioxygenase (hydroxylase). They demonstrated by experiments with 180 that both atoms of oxygen in catechol are exclusively derived from molecular oxygen. Subsequently, the incorporation of two atoms of molecular oxygen into substrates was established by tracer experiments with benzene 1,2-dioxygenase204 and benzoate 1,2-dioxygenase206. ... 

However, recent x-ray studies on p-hydroxybenzoate-p-hydroxybenzoate hydroxylase binary complex crystals clearly show the aromatic substrate is bound at the flavin 4a-5 edge and orthogonal to the isoalloxazine plane (29). Unless this binary complex structure is highly misinformative, it can be inferred that in the 02, p-hydroxy-benzoate, enzyme ternary active complex, oxygen transfer is in the 4a,5 region, not the la, 1 region of the bound FAD, which rules out la-OOH derivatives as important oxygenating intermediates for this enzyme. 

It has been suggested that active transport systems for benzoate (Thayer and Wheelis 1982) and for mandelate (Higgins and Mandelstam 1972) are involved. In Rhizobium leguminosarum, 4-hydroxybenzoate hydroxylase activity is required for the uptake of 4-hydroxybenzoate (Wong et al. 1994), while in P. putida a gene cluster pcaRKF is involved in the transport of 4-hydroxybenzoate into the cells, their chemotactic response to the substrate and its degradation by ring hydroxylation (Harwood et al. 1994 Nichols and Harwood 1997). The situation for phenylacetate transport into P. putida U is... 

Gibson, J., M. Dispensa, and C. S. Harwood. 1997. 4-Hydroxybenzoyl coenzyme A reductase dehydroxylating is required for anaerobic degradation of 4-hydrozy-benzoate by Rhodopseudomonas palustris and shares features with molybdenum-containing hydroxylases. J. Bacteriol. 179 634—642. 

Other fungal CYP families identified include a benzoate para-hydroxylase from Aspergillus niger and a cycloheximide inducible CYP54 from... 

Figure 3. Proposed pathways to AA precursors. A) 3,4-dihydroxybenzaldehyde (3,4-DHBA) biosynthesis depicting the two possible routes from/ -coumaric acid to form 3,4-DHBA the oxidative ferulate and the non-oxidative benzoate pathways B) Tyramine biosynthesis. Arrows without labeling reflect chemical reactions that have not been enzymatically characterized. Enzymes that have been cloned, characterized and identified are labeled in black bold. Enzyme abbreviations PAL, phenylalanine ammonia -lyase C4H, cinnamate 4-hydroxylase C3H, coumarate 3-hydroxylase HBS, 4-hydroxybenzaldehyde synthase TYDC, tyrosine decarboxylase.

G. Alibert, R. Ranjeva and A. Boudet, Recherches sur les enzymes catalysant la formation des acides phenoliques chez Quercus ped mculata (Ehrh.). II. Localisation intracellulaire de la phenylalanine ammoniac-lyase, de la cinnamate 4-hydroxylase et de la "benzoate-synthase", Biochim. Biophys. Acta... 

On the way to baccatin III, there are several more steps. Two oxygenation reactions remain to be defined, and the corresponding gene are missing. These are the presumed cytochrome P450-mediated taxoid C-ip-hydroxylase and the C-4p,C-20-epoxidase, leading to the oxetane formation the oxidation of the C-9a-hydroxyl function, likely mediated by a cytochrome P450 hydroxylase and the transfer of three ester functions C-2 benzoate, C-4 acetate, and C-10 acetate. 

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