scholarly journals The Mandelate Pathway, an Alternative to the Phenylalanine Ammonia Lyase Pathway for the Synthesis of Benzenoids in Ascomycete Yeasts

2020 ◽  
Vol 86 (17) ◽  
Author(s):  
Maria Jose Valera ◽  
Eduardo Boido ◽  
Juan Carlos Ramos ◽  
Eduardo Manta ◽  
Rafael Radi ◽  
...  

ABSTRACT Benzenoid-derived metabolites act as precursors for a wide variety of products involved in essential metabolic roles in eukaryotic cells. They are synthesized in plants and some fungi through the phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) pathways. Ascomycete yeasts and animals both lack the capacity for PAL/TAL pathways, and metabolic reactions leading to benzenoid synthesis in these organisms have remained incompletely known for decades. Here, we show genomic, transcriptomic, and metabolomic evidence that yeasts use a mandelate pathway to synthesize benzenoids, with some similarities to pathways used by bacteria. We conducted feeding experiments using a synthetic fermentation medium that contained either 13C-phenylalanine or 13C-tyrosine, and, using methylbenzoylphosphonate (MBP) to inhibit benzoylformate decarboxylase, we were able to accumulate intracellular intermediates in the yeast Hanseniaspora vineae. To further confirm this pathway, we tested in separate fermentation experiments three mutants with deletions in the key genes putatively proposed to form benzenoids (Saccharomyces cerevisiae aro10Δ, dld1Δ, and dld2Δ strains). Our results elucidate the mechanism of benzenoid synthesis in yeast through phenylpyruvate linked with the mandelate pathway to produce benzyl alcohol and 4-hydroxybenzaldehyde from the aromatic amino acids phenylalanine and tyrosine, as well as sugars. These results provide an explanation for the origin of the benzoquinone ring, 4-hydroxybenzoate, and suggest that Aro10p has benzoylformate and 4-hydroxybenzoylformate decarboxylase functions in yeast. IMPORTANCE We present here evidence of the existence of the mandelate pathway in yeast for the synthesis of benzenoids. The link between phenylpyruvate- and 4-hydroxyphenlypyruvate-derived compounds with the corresponding synthesis of benzaldehydes through benzoylformate decarboxylation is demonstrated. Hanseniaspora vineae was used in these studies because of its capacity to produce benzenoid derivatives at a level 2 orders of magnitude higher than that produced by Saccharomyces. Contrary to what was hypothesized, neither β-oxidation derivatives nor 4-coumaric acid is an intermediate in the synthesis of yeast benzenoids. Our results might offer an answer to the long-standing question of the origin of 4-hydroxybenzoate for the synthesis of Q10 in humans.

1973 ◽  
Vol 134 (4) ◽  
pp. 891-897 ◽  
Author(s):  
A. M. D. Nambudiri ◽  
C. P. Vance ◽  
G. H. N. Towers

The effects of light on growth, pigmentation and the activities of enzymes involved in the deamination of phenylalanine and tyrosine and in the biosynthesis of hispidin were examined in Polyporus hispidus. Evidence is presented for the stimulation of phenylalanine ammonia-lyase activity by light. Tyrosine ammonia-lyase activity and aminotransferase activities for phenylalanine and tyrosine were higher in the dark. Tracer studies showed that conversion of cinnamate into p-coumarate is enhanced by light. p-Coumaric acid hydroxylase, catalysing the conversion of p-coumarate into caffeate, could be detected only in cultures exposed to light. These results suggest that the cinnamate pathway for the metabolism of phenylalanine, leading to hispidin synthesis, is regulated by light in P. hispidus.


1976 ◽  
Vol 31 (11-12) ◽  
pp. 693-699 ◽  
Author(s):  
W. Löffelhardt ◽  
H. Kindl

Abstract Membrane-Bound Enzyme Complexes, Anacystis nidulans, Thylakoids, Benzoate Synthase The photosynthetic procaryote Anacystis nidulans converts L-phenylalanine and L-tyrosine into benzoic acid and p-hydroxybenzoic acid, respectively. Results obtained with thylakoid fractions support the hypothesis that the reaction sequence is catalyzed by thylakoid-bound enzyme complexes consisting of phenylalanine ammonia-lyase and benzoate synthase or tyrosine ammonia-lyase and p-hydroxybenzoate synthase, respectively. Both complexes do not accept phenylacetic acids as substrates, and cinnamic acids only at a small extent. These properties suggest a striking similarity to a benzoic acid-synthesizing enzyme system from higher plants which is situated at the thylakoid membrane of chloroplasts. The respective complexes of Dunaliella marina and Porphyridium sp. were included in this comparison.


2021 ◽  
Vol 12 ◽  
Author(s):  
Jeffrey P. Simpson ◽  
Jacob Olson ◽  
Brian Dilkes ◽  
Clint Chapple

The synthesis of small organic molecules, known as specialized or secondary metabolites, is one mechanism by which plants resist and tolerate biotic and abiotic stress. Many specialized metabolites are derived from the aromatic amino acids phenylalanine (Phe) and tyrosine (Tyr). In addition, the improved characterization of compounds derived from these amino acids could inform strategies for developing crops with greater resilience and improved traits for the biorefinery. Sorghum and other grasses possess phenylalanine ammonia-lyase (PAL) enzymes that generate cinnamic acid from Phe and bifunctional phenylalanine/tyrosine ammonia-lyase (PTAL) enzymes that generate cinnamic acid and p-coumaric acid from Phe and Tyr, respectively. Cinnamic acid can, in turn, be converted into p-coumaric acid by cinnamate 4-hydroxylase. Thus, Phe and Tyr are both precursors of common downstream products. Not all derivatives of Phe and Tyr are shared, however, and each can act as a precursor for unique metabolites. In this study, 13C isotopic-labeled precursors and the recently developed Precursor of Origin Determination in Untargeted Metabolomics (PODIUM) mass spectrometry (MS) analytical pipeline were used to identify over 600 MS features derived from Phe and Tyr in sorghum. These features comprised 20% of the MS signal collected by reverse-phase chromatography and detected through negative-ionization. Ninety percent of the labeled mass features were derived from both Phe and Tyr, although the proportional contribution of each precursor varied. In addition, the relative incorporation of Phe and Tyr varied between metabolites and tissues, suggesting the existence of multiple pools of p-coumaric acid that are fed by the two amino acids. Furthermore, Phe incorporation was greater for many known hydroxycinnamate esters and flavonoid glycosides. In contrast, mass features derived exclusively from Tyr were the most abundant in every tissue. The Phe- and Tyr-derived metabolite library was also utilized to retrospectively annotate soluble MS features in two brown midrib mutants (bmr6 and bmr12) identifying several MS features that change significantly in each mutant.


Plants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 476 ◽  
Author(s):  
Pavel Feduraev ◽  
Liubov Skrypnik ◽  
Anastasiia Riabova ◽  
Artem Pungin ◽  
Elina Tokupova ◽  
...  

Reacting to environmental exposure, most higher plants activate secondary metabolic pathways, such as the metabolism of phenylpropanoids. This pathway results in the formation of lignin, one of the most important polymers of the plant cell, as well as a wide range of phenolic secondary metabolites. Aromatic amino acids, such as phenylalanine and tyrosine, largely stimulate this process, determining two ways of lignification in plant tissues, varying in their efficiency. The current study analyzed the effect of phenylalanine and tyrosine, involved in plant metabolism through the phenylalanine ammonia-lyase (PAL) pathway, on the synthesis and accumulation of phenolic compounds, as well as lignin by means of the expression of a number of genes responsible for its biosynthesis, based on the example of common wheat (Triticum aestivum L.).


1964 ◽  
Vol 19 (5) ◽  
pp. 398-405 ◽  
Author(s):  
M. H. Zenk ◽  
G. Müller

Feeding experiments with glucose- (2-14C), phenylalanine- (3-14C), tyrosine- (3-14C) and p-coumaric acid- (3-14C) showed that the latter three substances are incorporated in good yields into p-hydroxybenzoic acid in leaves of Catalpa ovata. Kinetic experiments showed that p-hydroxybenzoic acid is formed from phenylalanine via p-coumaric acid and the subsequent β-oxidation of the side chain. p-Hydroxybenzoic acid can also be synthetised by hydroxylation of benzoic acid, but this does not seem to be the biosynthetic route in Catalpa.Phenylalanine- (3-14C) is also incorporated into benzoic acid, protocatechuic acid, and vanillic acid by different plants; the radioactivity of the β-C atom of the amino acid was found in each case to be located in the carboxyl group of the C6 — C1 acid. This suggests that in higher plants the benzoic acids are formed from the corresponding cinnamic acids via β-oxidation.


2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Gheorghe M. Borja ◽  
Angelica Rodriguez ◽  
Kate Campbell ◽  
Irina Borodina ◽  
Yun Chen ◽  
...  

Abstract Background Aromatic amino acids and their derivatives are valuable chemicals and are precursors for different industrially compounds. p-Coumaric acid is the main building block for complex secondary metabolites in commercial demand, such as flavonoids and polyphenols. Industrial scale production of this compound from yeast however remains challenging. Results Using metabolic engineering and a systems biology approach, we developed a Saccharomyces cerevisiae platform strain able to produce 242 mg/L of p-coumaric acid from xylose. The same strain produced only 5.35 mg/L when cultivated with glucose as carbon source. To characterise this platform strain further, transcriptomic analysis was performed, comparing this strain’s growth on xylose and glucose, revealing a strong up-regulation of the glyoxylate pathway alongside increased cell wall biosynthesis and unexpectedly a decrease in aromatic amino acid gene expression when xylose was used as carbon source. Conclusions The resulting S. cerevisiae strain represents a promising platform host for future production of p-coumaric using xylose as a carbon source.


mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Madeline Vargas ◽  
Nikhil S. Malvankar ◽  
Pier-Luc Tremblay ◽  
Ching Leang ◽  
Jessica A. Smith ◽  
...  

ABSTRACTIt has been proposed thatGeobacter sulfurreducensrequires conductive pili for long-range electron transport to Fe(III) oxides and for high-density current production in microbial fuel cells. In order to investigate this further, we constructed a strain ofG. sulfurreducens, designated Aro-5, which produced pili with diminished conductivity. This was accomplished by modifying the amino acid sequence of PilA, the structural pilin protein. An alanine was substituted for each of the five aromatic amino acids in the carboxyl terminus of PilA, the region in whichG. sulfurreducensPilA differs most significantly from the PilAs of microorganisms incapable of long-range extracellular electron transport. Strain Aro-5 produced pili that were properly decorated with the multihemec-type cytochrome OmcS, which is essential for Fe(III) oxide reduction. However, pili preparations of the Aro-5 strain had greatly diminished conductivity and Aro-5 cultures were severely limited in their capacity to reduce Fe(III) compared to the control strain. Current production of the Aro-5 strain, with a graphite anode serving as the electron acceptor, was less than 10% of that of the control strain. The conductivity of the Aro-5 biofilms was 10-fold lower than the control strain’s. These results demonstrate that the pili ofG. sulfurreducensmust be conductive in order for the cells to be effective in extracellular long-range electron transport.IMPORTANCEExtracellular electron transfer byGeobacterspecies plays an important role in the biogeochemistry of soils and sediments and has a number of bioenergy applications. For example, microbial reduction of Fe(III) oxide is one of the most geochemically significant processes in anaerobic soils, aquatic sediments, and aquifers, andGeobacterorganisms are often abundant in such environments.Geobacter sulfurreducensproduces the highest current densities of any known pure culture, and close relatives are often the most abundant organisms colonizing anodes in microbial fuel cells that harvest electricity from wastewater or aquatic sediments. The finding that a strain ofG. sulfurreducensthat produces pili with low conductivity is limited in these extracellular electron transport functions provides further insight into these environmentally significant processes.


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