Bacterial Degradation of 4-Hydroxyphenylacetic Acid and Homoprotocatechuic Acid

Abstract

A species of Acinetobacter and two strains of Pseudomonas putida when grown with 4-hydroxyphenylacetic acid gave cell extracts that converted 3,4-dihydroxyphenylacetic acid (homoprotocatechuic acid) into carbon dioxide, pyruvate, and succinate. The sequence of enzyme-catalyzed steps was as follows: ring-fission by a 2,3-dioxygenase, nicotinamide adenine dinucleotide-dependent dehydrogenation, decarboxylation, hydration, aldol fission, and oxidation of succinic semialdehyde. Two new metabolites, 5-carboxymethyl-2-hydroxymuconic acid and 2-hydroxyhepta-2,4-diene-1,7-dioic acid, were isolated from reaction mixtures and a third, 4-hydroxy-2-ketopimelic acid, was shown to be cleaved by extracts to give pyruvate and succinic semialdehyde. Enzymes of this metabolic pathway were present in Acinetobacter grown with 4-hydroxyphenylacetic acid but were effectively absent when 3-hydroxyphenylacetic acid or phenylacetic acid served as sources of carbon.

Phenylacetate-coenzyme A ligase is induced during growth on phenylacetic acid in different bacteria of several genera

“…In contrast to the earlier work, other authors have found that none of the enzymes expected for a pathway through either 3,4-HPA or 2,5-HPA could be detected in PAA-grown cells [3,5,6]. For example Sparnins et al [3] showed that the enzymes for the 3,4-HPA pathway were present in 4-hydroxyphenylacetate-grown cells of an Acinetobacter strains but were not present in PAAgrown cells.…”

“…In contrast to the earlier work, other authors have found that none of the enzymes expected for a pathway through either 3,4-HPA or 2,5-HPA could be detected in PAA-grown cells [3,5,6]. For example Sparnins et al [3] showed that the enzymes for the 3,4-HPA pathway were present in 4-hydroxyphenylacetate-grown cells of an Acinetobacter strains but were not present in PAAgrown cells. Cooper and coworkers also demonstrated a pathway for both 3-and 4-hydroxyphenylacetate in E. coli via 3,4-HPA [4] but yet were unable to show a route for PAA catabolism in spite of isolated PAA-mutants and mapping essential genes involved [6].…”

“…Much stronger biochemical evidence has been obtained for a pathway for catabolism of 4-hydroxyphenylacetic acid through 3,4-HPA both in Pseudomonas putida and Acinetobacter strains [3,4] and in E. coli [4].…”

“…One compound for which there is some doubt as to whether such a route operates is phenylacetic acid (C6HsCH2COOH, PAA) in spite of PAA being a fairly common source of carbon and energy for bacteria from a wide range of different genera. Pathways have been described for monohydroxylated derivatives of PAA which fit into the general pattern of aromatic catabolism outlined above [2][3][4], but none of the possible routes which might be expected for PAA catabolism by analogy with other aromatic catabolism appear to operate for many PAA-degrading bacteria [3,5,6]. Recently, however, a single report of a new enzyme, phenylacetate-CoA (PA-CoA) ligase, which catalyses the reaction: ChHsCHzCOOH + CoA + ATP = C6HsCH2COCoA + AMP + PPi has been described in the PAA-degrading strain Pseudomonas putida U [7] and may be the first step of what would be a very novel route for aromatic catabolism under aerobic conditions.…”

5-Carboxymethyl-2-hydroxymuconic semialdehyde dehydrogenases of Escherichia coli C and Klebsiella pneumoniae M5a1 show very high N-terminal sequence homology

“…A meta-cleavage pathway for the catabolism of 4-hydroxyphenylacetate (4-HPA) via homoprotocatechuate (HPC; 3,4-dihydroxyphenylacetate) is found in a range of bacteria including enteric bacteria [1,2]. The genes involved are chromosomally-encoded and little is known about their genetic organisation and evolution.…”