Catabolism of L-tyrosine in Trichosporon cutaneum

Abstract

Protocatechuic acid was a catabolite in the degradation of L-tyrosine by Trichosporon cutaneum. Intact cells oxidized to completion various compounds proposed as intennediates in this conversion, but they did not readily oxidize catabolites of the homogentisate and homoprotocatechuate metabolic pathways, which are known to function in other organisms. Cell extracts converted tyrosine first to 4-hydroxycinnamic acid and then to 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid. The proposed hydration product of 4-hydroxycinnamic acid, namely, fl-(4-hydroxyphenyl)-hydracrylic acid, was synthesized chemically, and its enzymatic degradation to 4-hydroxybenzaldehyde was shown to be dependent upon additions of adenosine triphosphate and coenzyme A. The hydroxylase that attacked 4-hydroxybenzoate showed a specific requirement for reduced nicotinamide adenine dinucleotide phosphate. Protocatechuate, the product of this reaction, was oxidized by cell extracts supplemented with reduced nicotinamide adenine dinucleotide or, less effectively, with reduced nicotinamide adenine dinucleotide phosphate, but these extracts contained no ring fission dioxygenase for protocatechuate. Evidence is presented that the principal hydroxylation product of protocatechuate was hydroxyquinol, the benzene nucleus of which was cleaved oxidatively to give maleylacetic acid.

The crystal structure of maleylacetate reductase fromRhizobiumsp. strain MTP-10005 provides insights into the reaction mechanism of enzymes in its original family

“…In fungi and yeasts, maleylacetate reductases are involved in the catabolism of common compounds such as phenol, tyrosine, benzoate, 4-hydroxybenzoate, and resorcinol. [3][4][5][6][7] In bacteria, maleylacetate reductases contribute to the degradation of resorcinol, 2,4-dihydroxybenzoate (bresorcylate), and 2,6-dihydroxybenzoate (g-resorcylate) via hydroxyquinol followed by maleylacetate. [8][9][10][11][12] During a screening experiment, Rhizobium sp.…”

Degradation of aromatic compounds through the β‐ketoadipate pathway is required for pathogenicity of the tomato wilt pathogen Fusarium oxysporum f. sp. lycopersici

“…This compound and quinic acid are both metabolized in eukaryotes through the b-ketoadipate pathway (Harwood and Parales, 1996). Reduced growth of the mutant was also observed on the phenolic compounds ferulic acid, coumaric acid, vanillic acid, cinnamic acid, 4-hydroxybenzoic acid and 4-hydroxybenzaldehyde, all compounds which are degraded via the protocatechuate branch of the b-ketoadipate pathway in fungi (Cain et al, 1968;Harwood and Parales, 1996;Middelhoven, 1993;Sparnins et al, 1979). As expected, growth of the cmle mutant was not impaired on catechol, which is degraded via the catechol branch of the b-ketoadipate pathway and does not require CMLE (Harwood and Parales, 1996).…”

“…As no other carbon source was added to the minimal medium, growth on these media indicates the capacity of the strains to assimilate the respective aromatic com-pounds. The cmle deletion mutants (KO6 and KO9) and insertional mutants 72C7 and 75H3 displayed significantly reduced growth on minimal medium supplemented with ferulic acid, coumaric acid, vanillic acid, 4-hydroxybenzoic acid, 4-hydroxybenzaldehyde and cinnamic acid (Table 1).These are all compounds that are converted to protocatechuate and are subsequently degraded through the b-ketoadipate pathway (Cain et al, 1968;Harwood and Parales, 1996;Middelhoven, 1993;Sparnins et al, 1979). Growth was restored to the wild-type level in the complemented strains (Table 1).…”

Catabolism of 4-hydroxybenzoate in proceeds through initial oxidative decarboxylation by a FAD-dependent 4-hydroxybenzoate 1-hydroxylase

“…Relatively little is known about the aromatic hydroxylases involved in the catabolism of 4-hydroxybenzoate by yeasts [11,12]. For the basid-iomycete Trichosporon cutaneum it was reported that 4-hydroxybenzoate is metabolized via 3,4-dihydroxybenzoate and the 1,2,4-trihydroxybenzene branch of the/3-ketoadipate pathway [13,14]. This reaction sequence involves two aromatic hydroxylases [14][15][16].…”