Oxidation of phenylacetic acid by <i>Penicillium chrysogenum</i>

Hockenhull, D. J. D.; Walker, A. D.; Wilkin, G. D.; Winder, Frank G.

doi:10.1042/bj0500605

Cited by 20 publications

(9 citation statements)

References 3 publications

(1 reference statement)

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“…Industrial penicillin production by Penicillium chrysogenum strains requires the addition of PhAc, which is the side-chain precursor for the synthesis of penicillin G. Part of the added PhAc is oxidized (26), and it is not transformed into penicillin. Therefore, strain improvement programs using mutation and selection techniques have been directed to prevent such oxidation (27).…”

Section: Discussionmentioning

confidence: 99%

Disruption of phacA, an Aspergillus nidulans Gene Encoding a Novel Cytochrome P450 Monooxygenase Catalyzing Phenylacetate 2-Hydroxylation, Results in Penicillin Overproduction

Mingot

Peñalva

Fernández-Cañón³

1999

Journal of Biological Chemistry

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Aspergillus nidulans utilizes phenylacetate as a carbon source via homogentisate, which is degraded to fumarate and acetoacetate. Mutational evidence strongly suggested that phenylacetate is converted to homogentisate through two sequential hydroxylating reactions in positions 2 and 5 of the aromatic ring. Using cDNA substraction techniques, we have characterized a gene, denoted phacA, whose transcription is strongly induced by phenylacetate and which putatively encodes a cytochrome P450 protein. A disrupted phacA strain does not grow on phenylacetate but grows on 2-hydroxy-or 2,5-dihydroxyphenylacetate. Microsomal extracts of the disrupted strain are deficient in the NADPH-dependent conversion of phenylacetate to 2-hydroxyphenylacetate. We conclude that PhacA catalyzes the ortho-hydroxylation of phenylacetate, the first step of A. nidulans phenylacetate catabolism. The involvement of a P450 enzyme in the ortho-hydroxylation of a monoaromatic compound has no precedent. In addition, PhacA shows substantial sequence divergence with known cytochromes P450 and defines a new family of these enzymes, suggesting that saprophytic fungi may represent a source of novel cytochromes P450.Phenylacetate is a precursor for benzylpenicillin production. phacA disruption increases penicillin production 3-5-fold, indicating that catabolism competes with antibiotic biosynthesis for phenylacetate and strongly suggesting strategies for Penicillium chrysogenum strain improvement by reverse genetics.Aerobic degradation of aromatic hydrocarbons by microbes involves the action of oxygenases (enzymes that incorporate one or two atoms from dioxygen into substrates) acting at two different levels in specific catabolic pathways (1, 2). First, oxygenase enzymes acting at the upstream segment of these pathways incorporate one (monooxygenases, aromatic ring hydroxylases) or two (aromatic ring dioxygenases) oxygen atoms into the aromatic substrate as hydroxyl groups, preparing the ring for a subsequent ring-opening step. In this second step, the dihydroxylated aromatic ring is opened by ring-cleavage dioxygenases.Monooxygenases are a mechanistically diverse group of enzymes (1) including, for example, flavoproteins such as p-hydroxybenzoate hydroxylase (3), multicomponent enzymes such as Pseudomonas mendocina toluene 4-monoxygenase, in which one of the terminal hydroxylase polypeptides contains a binuclear iron cluster (4), or heme-containing cytochrome P450 systems. Monooxygenases of the cytochrome P450 superfamily (5, 6) are widely distributed among living organisms and catalyze a multiplicity of biosynthetic and catabolic reactions, usually with narrow substrate specificity, including the hydroxylation of a variety of lipophylic drugs.In common with other saprophytic microbes, the genetically amenable, obligate aerobic fungus Aspergillus nidulans shows notable metabolic versatility. For example, it can use the aromatic hydrocarbon compound phenylacetate (PhAc) 1 as sole carbon source. Despite the abundant information available on the cataboli...

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Section: Discussionmentioning

confidence: 99%

Disruption of phacA, an Aspergillus nidulans Gene Encoding a Novel Cytochrome P450 Monooxygenase Catalyzing Phenylacetate 2-Hydroxylation, Results in Penicillin Overproduction

Mingot

Peñalva

Fernández-Cañón³

1999

Journal of Biological Chemistry

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“…Octopamine, an invertebrate neurotransmitter also found in mammalian brain, is metabolised to 4-hydroxy- mandelate which is excreted [45]. L-Phenylalanine, phenylacetate and L-tyrosine are converted into mandelate and 4-hydroxymandelate by a wide range of organisms including Polyporus hispidus [46], Penicillium chrysogenum [47], Aspergillus niger [48], phytoplankton [49] and red algae [50], although some of the enzymes thought to be involved in the postulated metabolic pathways ( Fig. 5) have not been identified and in particular the mechanism whereby the a-carbon of phenylacetate (or 4-hydroxyphenylacetate) is hydroxylated to give mandelate (or 4-hydroxymandelate) is not known.…”

Section: Mandelate and Related Com-pounds In Naturementioning

confidence: 99%

“…[104] and Flavobacterium sp. [105]; c, Penicillium chrysogenum [47], mechanism uncertain, see Section 3; d, Pseudomonas putida [77], Lactobacillus sp. [106], Bacillus sp.…”

Section: Degradation Of Ring-substituted Mandelatesmentioning

confidence: 99%

Microbial metabolism of mandelate: a microcosm of diversity

Fewson

1988

FEMS Microbiology Letters

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This review highlights the diversity of prokaryotic and eukaryotic microorganisms that can metabolise mandelate and it describes how a wide range of compounds related to mandelate is formed in many environments. The chief aspects that are summarised include the various pathways whereby mandelate and its structural analogues are converted into catechol or protocatechuate, the properties of the enzymes that are involved in the pathways, and the regulation and genetics of the pathways. The review incorporates the idea that the study of peripheral metabolic pathways is particularly useful for illuminating evolutionary speculations and it concludes with a list of questions that need to be answered.

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“…A greater variety of pathways have been described for fungi. The oxidation of phenylacetic acid by Penicillium chrysogenum proceeded through mandelic acid to benzaldehyde (HOCKENHULL et al 1952), while a strain of Aspergillus niger 256 BROWN and SWINBURNE produced protocatechuic acid, the pathway involving the formation of 3-hydroxyphenylacetic acid and 3-hydroxybenzyl alcohol (SUGUMARAN et al 1972). BOCKS (1967), however, showed that the Mulder strain of A. niger metabolized phenylacetic acid to 2-, 3-and 4-hydroxyphenylacetic acids and 2,5-dihydroxyphenylacetic acid (homogentisic acid).…”

Section: Resultsmentioning

confidence: 99%