Phenanthrene dioxygenase

Saito A, T Iwabuchi, S Harayama (2000) A novel phenanthrene dioxygenase from Nocardioides sp. strain KP7 expression in Escherichia coli. J Bacteriol 182 2134-2141. 

The enzymes involved in the degradation of phenanthrene by Nocardioides sp. strain KP7 have been characterized. In this strain, the genes are chromosomal, and phdA and phdB encoding the a- and P-subunits of the dioxygenase, phdC and phdD that encode the ferredoxin, and ferredoxin reductase have been cloned and sequenced (Saito et al. 2000). The order of the genes... 

Strain PI5 was grown on phenanthrene by a known pathway in which salicylate is an intermediate. Pre-incubation with phenanthrene and downstream intermediates through salicylate stimulated PAH dioxygenase activity and initial rates of phenanthrene removal, suggesting that salicylate was the inducer of this activity. 

Phenanthrene is transformed to trans-9,10- (major), trans-1,2- (minor), and trans-3,4-dihydrodiol (minor) metabolites via monooxygenase-catalyzed formation of arene oxides, followed by epoxide hydrolase-catalyzed hydration in mammalian liver systems.219-221 In bacterial cultures, phenanthrene is converted to cis-3,4- (major) and cis-1,2- dihydrodiols (minor) through the action of dioxygenase enzymes and molecular oxygen.221,222 Recently, Boyd et al.10 have prepared trons-3,4-dihydroxy-1,2,3,4-tetrahydrophenanthrene (359) and cis-3,4-dihydroxy-1,2,3,4-tetrahydrophenanthrene (360) in optically pure forms. These compounds have made possible the determination of the configurations of the trans- and cis-3,4-dihydrodiol metabolites of phenanthrene (361 and 362) as (-)-(3R,4R) and ( + )-(3S,4R), respectively. 

Phenanthrene is more readily degraded than anthracene, and two different pathways are followed after cleavage of the peripheral ring in one, the naphthalene pathway via salicylate is used (Evans et al. 1965), whereas in the other o-phthalate and 3,4-dihydroxybenzoate are involved (Kiyohara et al. 1976 Kiyohara and Nagao 1978 Barnsley 1983) (Figure 6.38). The enzymes involved, l-hydroxy-2-naphthoate dioxygenase (Iwabuchi and Harayama... 

The structure of the substrates is not necessarily restricted to monocyclic aromatic compounds such as those shown in Scheme 16.1-2. The dioxygenase activity of Pseudomonas putida and Beijerinckia species has been used exclusively for the synthesis of cis dihydrodiols from polycyclic 202 and heterocyclic 203 derivatives. Such products have been obtained from naphthalene, anthracene, phenanthrene, benz[a]pyrene, benz[a]anthracene, and methylsubstituted benz[a]anthracenes, and... 

A number of instances can be cited from the literature wherein the isosteres had similar transformations. Bacterial dioxygenase-catalyzed ci5-dihydroxylation of the tetracyclic arene benzo[c]phenanthrene was found to occur exclusively at fjord region (cavity region) bonds. The isosteric compounds benzo[b]naphthol [l,2-d]furan and benzo[b]naphthol[l,2-d]thiophene were also similarly ci5-dihydroxylated at the fjord region bonds by bacterial dioxygenases (Boyd et al., 2001) (see Fig. 4.3). The isosteres 1,2-dihydronaphthalene, 2,3-dihydrobenzothiophene, and 2,3-dihydro-benzofuran gave similar corresponding diol products on incubation with Pseudomonas putida UV4. Microbes that possess the metabolic pathways to metabolize benzene, when substituted by... 

Alternatively, a phenanthrene alkaloid may also be oxidized by catechol dioxygenase enzymes at the C-5,6 or at the C-6,7 bonds, to produce such novel alkaloids as chiloenamine and santiagonamine (Shamma et al. 1983, Valencia et al. 1984) (Fig. 1). 

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