Área Enología y Biotecnología de Fermentaciones, Departamento Ciencia y Tecnología Alimentos, Universidad de la Republica, Montevideo, Uruguay.
Laboratorio de Biotecnología de Aromas, Departamento de Química Orgánica, Universidad de la Republica, Montevideo, Uruguay.
Appl Environ Microbiol. 2020 Aug 18;86(17). doi: 10.1128/AEM.00701-20.
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 C-phenylalanine or C-tyrosine, and, using methylbenzoylphosphonate (MBP) to inhibit benzoylformate decarboxylase, we were able to accumulate intracellular intermediates in the yeast To further confirm this pathway, we tested in separate fermentation experiments three mutants with deletions in the key genes putatively proposed to form benzenoids (Δ, Δ, and 2Δ 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. 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. 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 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.
苯并衍生代谢物作为前体，参与真核细胞中各种重要代谢途径的产物合成。它们通过苯丙氨酸氨裂解酶（PAL）和酪氨酸氨裂解酶（TAL）途径在植物和一些真菌中合成。子囊菌酵母和动物都缺乏 PAL/TAL 途径的能力，几十年来，这些生物中导致苯并合成的代谢反应仍不完全清楚。在这里，我们通过基因组、转录组和代谢组学证据表明，酵母使用扁桃酸途径合成苯并，与细菌使用的途径有一些相似之处。我们使用含有 C-苯丙氨酸或 C-酪氨酸的合成发酵培养基进行了喂养实验，并用甲基苯甲酰膦酸（MBP）抑制苯甲酰甲酸脱羧酶，我们能够在酵母中积累细胞内中间体，以进一步确认该途径，我们在三个关键基因缺失的突变体（Δ、Δ和 2Δ 菌株）的单独发酵实验中进行了测试。我们的结果阐明了酵母中苯并合成的机制，通过苯丙酮酸与扁桃酸途径相连，从芳香族氨基酸苯丙氨酸和酪氨酸以及糖中产生苄醇和 4-羟基苯甲醛，这些结果解释了苯醌环、4-羟基苯甲酸的起源，并表明 Aro10p 在酵母中具有苯甲酰甲酸和 4-羟基苯甲酰甲酸脱羧酶的功能。我们在这里提供了酵母中扁桃酸途径存在的证据，用于苯并的合成。通过苯甲酰甲酸脱羧作用，证明了苯丙酮酸和 4-羟苯基丙酮酸衍生化合物与相应的苯甲醛合成之间的联系。在这些研究中使用了，因为它能够产生比产生 2 个数量级更高水平的苯并衍生物。与假设相反，β-氧化衍生物或 4-香豆酸都不是酵母苯并合成的中间产物。我们的结果可能为人类 Q10 合成中 4-羟基苯甲酸的起源这一长期存在的问题提供了答案。
