Phenylacetate is derived from the metabolism of phenylalanine, Z-phenylacetaldoxime, styrene, and many other compounds. Phenylacetate aerobic metabolism in fungi usually proceeds by oxidation to homogentisate (Cox et al., 1996), as shown in the left branch below. In bacteria, this rarely occurs, rather the initial step is ligation with CoA. Pseudomonas putida U uses both pathways; 4-hydroxyphenylacetate is metabolised via oxidation and phenylacetate via ligation with CoA (Olivera et al., 1994). Ligation is followed by epoxide formation, isomerization of the epoxide to an oxepin, and hydrolytic ring cleavage, to eventually produce acetyl-CoA and succinyl-CoA, as shown in the right branch. This pathway is found in 16% of 640 bacteria whose genomes have been sequenced, including Pseudomonas putida and Escherichia coli (Teufel et al., 2010).
Under anaerobic conditions, the denitrifying bacterium Thauera aromatica oxidizes phenylacetate to benzoyl-CoA via the intermediates phenylacetyl-CoA and phenylglyoxylate (benzoylformate) (Rhee and Fuchs, 1999). This pathway is shown in the KEGG database.
The following is a text-format aerobic phenylacetate pathway map. Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (8k) format.
from the Z-Phenylacetaldoxime, Styrene and Atropine Phenylacetate <--------- Pathways ---------> Phenylacetate Exophiala jeanselmei Pseudomonas putida and many others and many others | | | phenylacetate | phenylacetate--CoA | hydroxylase | ligase | | v v 2-Hydroxyphenylacetate Phenylacetyl-CoA | | | 2-hydroxyphenyl- | phenylacetyl-CoA | acetate hydroxylase | monooxygenase | | v v Homogentisate 1,2-Epoxyphenylacetyl-CoA | | | | 1,2-epoxyphenylacetyl-CoA v | isomerase to the | Tyrosine v Pathway 2-[(2E)-2,3-dihydrooxepin- 2-ylidene]acetyl-CoA | | 2-oxepin-2(3H)-ylidene- | acetyl-CoA hydrolase v 3-oxo-5,6-dehydrosuberyl-CoA | | | 3-oxo-5,6-dehydrosuberyl-CoA | thiolase | v 5-Carboxy-2-pentenoyl-CoA | | | v to the Cyclohexane Pathway
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