Lapadatescu C, Giniès C, Le Quéré J L, Bonnarme P
Laboratoire de Recherches Sur les Arômes (LRSA), Institut National de la Recherche Agronomique, 21034 Dijon cedex, France.
Appl Environ Microbiol. 2000 Apr;66(4):1517-22. doi: 10.1128/AEM.66.4.1517-1522.2000.
Aryl metabolite biosynthesis was studied in the white rot fungus Bjerkandera adusta cultivated in a liquid medium supplemented with L-phenylalanine. Aromatic compounds were analyzed by gas chromatography-mass spectrometry following addition of labelled precursors ((14)C- and (13)C-labelled L-phenylalanine), which did not interfere with fungal metabolism. The major aromatic compounds identified were benzyl alcohol, benzaldehyde (bitter almond aroma), and benzoic acid. Hydroxy- and methoxybenzylic compounds (alcohols, aldehydes, and acids) were also found in fungal cultures. Intracellular enzymatic activities (phenylalanine ammonia lyase, aryl-alcohol oxidase, aryl-alcohol dehydrogenase, aryl-aldehyde dehydrogenase, lignin peroxidase) and extracellular enzymatic activities (aryl-alcohol oxidase, lignin peroxidase), as well as aromatic compounds, were detected in B. adusta cultures. Metabolite formation required de novo protein biosynthesis. Our results show that L-phenylalanine was deaminated to trans-cinnamic acid by a phenylalanine ammonia lyase and trans-cinnamic acid was in turn converted to aromatic acids (phenylpyruvic, phenylacetic, mandelic, and benzoylformic acids); benzaldehyde was a metabolic intermediate. These acids were transformed into benzaldehyde, benzyl alcohol, and benzoic acid. Our findings support the hypothesis that all of these compounds are intermediates in the biosynthetic pathway from L-phenylalanine to aryl metabolites. Additionally, trans-cinnamic acid can also be transformed via beta-oxidation to benzoic acid. This was confirmed by the presence of acetophenone as a beta-oxidation degradation intermediate. To our knowledge, this is the first time that a beta-oxidation sequence leading to benzoic acid synthesis has been found in a white rot fungus. A novel metabolic scheme for biosynthesis of aryl metabolites from L-phenylalanine is proposed.
在添加了L-苯丙氨酸的液体培养基中培养的白腐真菌烟管菌（Bjerkandera adusta）中，对芳基代谢物的生物合成进行了研究。添加不会干扰真菌代谢的标记前体（（14）C和（13）C标记的L-苯丙氨酸）后，通过气相色谱-质谱法分析芳香族化合物。鉴定出的主要芳香族化合物为苯甲醇、苯甲醛（苦杏仁香气）和苯甲酸。在真菌培养物中还发现了羟基和甲氧基苄基化合物（醇、醛和酸）。在烟管菌培养物中检测到细胞内酶活性（苯丙氨酸解氨酶、芳基醇氧化酶、芳基醇脱氢酶、芳基醛脱氢酶、木质素过氧化物酶）和细胞外酶活性（芳基醇氧化酶、木质素过氧化物酶）以及芳香族化合物。代谢物的形成需要从头进行蛋白质生物合成。我们的结果表明，L-苯丙氨酸通过苯丙氨酸解氨酶脱氨生成反式肉桂酸，反式肉桂酸又依次转化为芳香酸（苯丙酮酸、苯乙酸、扁桃酸和苯甲酰甲酸）；苯甲醛是一种代谢中间体。这些酸被转化为苯甲醛、苯甲醇和苯甲酸。我们的研究结果支持了这样一种假设，即所有这些化合物都是从L-苯丙氨酸到芳基代谢物的生物合成途径中的中间体。此外，反式肉桂酸也可以通过β-氧化转化为苯甲酸。苯乙酮作为β-氧化降解中间体的存在证实了这一点。据我们所知，这是首次在白腐真菌中发现导致苯甲酸合成的β-氧化序列。提出了一种从L-苯丙氨酸生物合成芳基代谢物的新代谢方案。
