Bacterial phenylalanine and phenylacetate catabolic pathway revealed
2010; National Academy of Sciences; Volume: 107; Issue: 32 Linguagem: Inglês
10.1073/pnas.1005399107
ISSN1091-6490
AutoresRobin Teufel, Victoria Mascaraque, Wael Ismail, Michaela Voss, Julián Perera, Wolfgang Eisenreich, Wolfgang Haehnel, Georg Fuchs,
Tópico(s)Microbial Metabolic Engineering and Bioproduction
ResumoAromatic compounds constitute the second most abundant class of organic substrates and environmental pollutants, a substantial part of which (e.g., phenylalanine or styrene) is metabolized by bacteria via phenylacetate. Surprisingly, the bacterial catabolism of phenylalanine and phenylacetate remained an unsolved problem. Although a phenylacetate metabolic gene cluster had been identified, the underlying biochemistry remained largely unknown. Here we elucidate the catabolic pathway functioning in 16% of all bacteria whose genome has been sequenced, including Escherichia coli and Pseudomonas putida . This strategy is exceptional in several aspects. Intermediates are processed as CoA thioesters, and the aromatic ring of phenylacetyl-CoA becomes activated to a ring 1,2-epoxide by a distinct multicomponent oxygenase. The reactive nonaromatic epoxide is isomerized to a seven-member O-heterocyclic enol ether, an oxepin. This isomerization is followed by hydrolytic ring cleavage and β-oxidation steps, leading to acetyl-CoA and succinyl-CoA. This widespread paradigm differs significantly from the established chemistry of aerobic aromatic catabolism, thus widening our view of how organisms exploit such inert substrates. It provides insight into the natural remediation of man-made environmental contaminants such as styrene. Furthermore, this pathway occurs in various pathogens, where its reactive early intermediates may contribute to virulence.
Referência(s)