Degradation of phenylalanine and tyrosine by <i>Sporobolomyces roseus</i>

Moore, Keith; Rao, P. V. Subba; Towers, G.H.N.

doi:10.1042/bj1060507

Cited by 52 publications

(24 citation statements)

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“…The metabolic branch toward phenylpyruvate and onward resembles metabolism already described for several fungal species (35,(47)(48)(49). Furthermore, the modeling results suggest the conversion of phenylalanine to tyrosine via a phenylalanine hydroxylase.…”

Section: Discussionmentioning

confidence: 52%

“…Interestingly and in contrast to findings for human metabolism, labeled tyrosine was not de-tected, suggesting the absence of a functional phenylalanine hydroxylase (35). In basidiomycetes (e.g., Schizophyllum commune), phenylalanine also can be catabolized through the phenylpropanoid pathway, in which phenylalanine is converted into cinnamate by a phenylalanine ammonia lyase (47)(48)(49).…”

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confidence: 99%

“…The metabolism of aromatic compounds in filamentous fungi presents a high degree of metabolic diversity. Several biochemical studies showed that, in ascomycetous fungi, phenylacetate is an intermediate of phenylalanine catabolism (35,(47)(48)(49). [ 14 C]L-phenylalanine tracer experiments in Aspergillus niger showed that L-phenylalanine metabolism yielded metabolites such as phenylacetate, 2-and 4-hydroxyphenylacetate, and homogentisate, as well as 4-hydroxymandelate and protocatechuate.…”

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confidence: 99%

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Resolving Phenylalanine Metabolism Sheds Light on Natural Synthesis of Penicillin G in Penicillium chrysogenum

et al. 2012

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The industrial production of penicillin G by Penicillium chrysogenum requires the supplementation of the growth medium with the side chain precursor phenylacetate. The growth of P. chrysogenum with phenylalanine as the sole nitrogen source resulted in the extracellular production of phenylacetate and penicillin G. To analyze this natural pathway for penicillin G production, chemostat cultures were switched to [U-13 C]phenylalanine as the nitrogen source. The quantification and modeling of the dynamics of labeled metabolites indicated that phenylalanine was (i) incorporated in nascent protein, (ii) transaminated to phenylpyruvate and further converted by oxidation or by decarboxylation, and (iii) hydroxylated to tyrosine and subsequently metabolized via the homogentisate pathway. The involvement of the homogentisate pathway was supported by the comparative transcriptome analysis of P. chrysogenum cultures grown with phenylalanine and with (NH 4 ) 2 SO 4 as the nitrogen source. This transcriptome analysis also enabled the identification of two putative 2-oxo acid decarboxylase genes (Pc13g9300 and Pc18g01490). cDNAs of both genes were cloned and expressed in the 2-oxo-acid-decarboxylase-free Saccharomyces cerevisiae strain CEN.PK711-7C (pdc1 pdc5 pdc6⌬ aro10⌬ thi3⌬). The introduction of Pc13g09300 restored the growth of this S. cerevisiae mutant on glucose and phenylalanine, thereby demonstrating that Pc13g09300 encodes a dual-substrate pyruvate and phenylpyruvate decarboxylase, which plays a key role in an Ehrlich-type pathway for the production of phenylacetate in P. chrysogenum. These results provide a basis for the metabolic engineering of P. chrysogenum for the production of the penicillin G side chain precursor phenylacetate.

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Section: Discussionmentioning

confidence: 52%

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Resolving Phenylalanine Metabolism Sheds Light on Natural Synthesis of Penicillin G in Penicillium chrysogenum

et al. 2012

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“…In other cases, however, the experimental results would favor the view that one enzyme is capable of catalyzing the two reactions (23). In surveys made with a wide variety of organisms there are no examples in which an extract has activity with tyrosine but not with phenylalanine, and indeed, no cases in which higher activity is observed with tyrosine than with phenylalanine (1,2,21,28,29). Attempts to purify a specific tyrosine ammonialyase have resulted in preparations which are three to four times more active with phenylalanine than tyrosine when assayed at saturating substrate concentrations (15,22).…”

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l-Phenylalanine Ammonia-Lyase (Maize)

1971

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L-Phenylalanine ammonia-lyase (E.C. 4.3.1.5) from maize is active with L-tyrosine and L-phenylalanine and exhibits atypical Michaelis-Menten kinetics with both substrates. With phenylalanine as a substrate, the pH optimum is 8.7 and with tyrosine, 7.7. The estimated Kin at high substrate concentrations is 0.27 mM for phenylalanine and 0.029 mM for tyrosine. However, the Vmax with phenylalanine is eight times higher than the Vmax with tyrosine when both are measured at pH 8.7, and 7 times higher when both are measured at their pH optima. The following evidence leads us to the conclusion that there is a common catalytic site for both substrates: (a) It is impossible to appreciably alter the ratio of the two activities during purification and isoelectric focusing. (b) The ratio of the products formed in mixed substrate experiments is in good agreement with the ratio predicted from the estimated Km values. (c) NaBH4 reduces both activities to the same degree and L-phenylalanine, L-tyrosine, cinnamate, and p-coumarate protect both activities against NaBH4 reduction to the same degree. In contrast, the enzyme isolated from potato, which does not act on L-tyrosine, is not protected against reduction by either L-tyrosine or p-coumarate. However, both enzymes appear to have a dehydroalanine-containing prosthetic group.The enzyme L-phenylalanine ammonia-lyase (EC 4.1.3.5), which converts L-phenylalanine to trans-cinnamate and ammonia has been isolated and purified to varying degrees from a number of sources (6,10,13,16,19,20,23,26 however, the experimental results would favor the view that one enzyme is capable of catalyzing the two reactions (23). In surveys made with a wide variety of organisms there are no examples in which an extract has activity with tyrosine but not with phenylalanine, and indeed, no cases in which higher activity is observed with tyrosine than with phenylalanine (1, 2, 21, 28, 29). Attempts to purify a specific tyrosine ammonialyase have resulted in preparations which are three to four times more active with phenylalanine than tyrosine when assayed at saturating substrate concentrations (15,22).Resolving the question of enzyme specificity or lack of it when working with a nonhomogeneous system is a very difficult one. Factors such as relative Vmax and Km, as well as pH optima, influence the results of certain types of inhibitor and mixed substrate experiments and these factors must be taken into account when the results are interpreted. In this paper we characterize the L-tyrosine ammonia-lyase activity of maize and present the several lines of evidence which lead us to believe that both L-tyrosine and L-phenylalanine react at the same active site. The question of specificity must be answered before we can understand the in vivo function and control of this enzyme. MATERIALS AND METHODSEnzyme Sources. L-Phenylalanine ammonia-lyase was purified through the Agarose step from light exposed potato tuber slices (12). The enzyme from maize was purified by a revised procedure (24) which will be p...

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“…In Basidiomycetes the C 6 -C 3 compounds are converted into C 6 -C 1 compounds. In Sporobolomyces roseus, this was found to involve the conversion of C 6 -C 3 compounds, such as cinnamic, p-coumaric, and caffeic acids, into a C 6 -C 1 compound-protocatechuic acid-by þ oxidation in the washed cells, probably via benzoic and p-hydroxybenzoic acids (Moore et al, 1968). The second pathway is the formation of protocatechuic acid and gallic acid from dehydroshikimic acid.…”

Section: Biosynthesis Of Phenolic Compounds From Mushrooms or Fungimentioning

confidence: 99%

Nutritional Value and Health Benefits of Mushrooms

Cheung

2008

Mushrooms as Functional Foods

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Degradation of phenylalanine and tyrosine by Sporobolomyces roseus

Cited by 52 publications

References 23 publications

Resolving Phenylalanine Metabolism Sheds Light on Natural Synthesis of Penicillin G in Penicillium chrysogenum

Resolving Phenylalanine Metabolism Sheds Light on Natural Synthesis of Penicillin G in Penicillium chrysogenum

l-Phenylalanine Ammonia-Lyase (Maize)

Nutritional Value and Health Benefits of Mushrooms

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