Metabolism of 4-Amino-3-hydroxybenzoic Acid by<i>Bordetella</i>sp. Strain 10d: A Different Modified<i>Meta</i>-Cleavage Pathway for 2-Aminophenols
作者:Chika ORII、Shinji TAKENAKA、Shuichiro MURAKAMI、Kenji AOKI
DOI:10.1271/bbb.60264
日期:2006.11.23
Bordetella sp. strain 10d metabolizes 4-amino-3-hydroxybenzoic acid via 2-hydroxymuconic 6-semialdehyde. Cell extracts from 4-amino-3-hydroxybenzoate-grown cells showed high NAD+-dependent 2-hydroxymuconic 6-semialdehyde dehydrogenase, 4-oxalocrotonate tautomerase, 4-oxalocrotonate decarboxylase, and 2-oxopent-4-enoate hydratase activities, but no 2-hydroxymuconic 6-semialdehyde hydrolase activity. These enzymes involved in 4-amino-3-hydroxybenzoate metabolism were purified and characterized. When 2-hydroxymuconic 6-semialdehyde was used as substrate in a reaction mixture containing NAD+ and cell extracts from 4-amino-3-hydroxybenzoate-grown cells, 4-oxalocrotonic acid, 2-oxopent-4-enoic acid, and 4-hydroxy-2-oxovaleric acid were identified as intermediates, and pyruvic acid was identified as the final product. A complete pathway for the metabolism of 4-amino-3-hydroxybenzoic acid in strain 10d is proposed. Strain 10d metabolized 2-hydroxymuconic 6-semialdehyde derived from 4-amino-3-hydroxybenzoic acid via a dehydrogenative route, not via a hydrolytic route. This proposed metabolic pathway differs considerably from the modified meta-cleavage pathway of 2-aminophenol and those previously reported for methyl- and chloro-derivatives.
Bordetella sp. 10d株通过2-羟基穆康酸6-半醛代谢4-氨基-3-羟基苯甲酸。来自于培养于4-氨基-3-羟基苯甲酸的细胞的细胞提取物显示出高水平的NAD+-依赖性2-羟基穆康酸6-半醛脱氢酶、4-草酰克罗通酸互变异构酶、4-草酰克罗通酸脱羧酶和2-氧戊-4-烯酸水合酶活性,但没有检测到2-羟基穆康酸6-半醛水解酶活性。这些参与4-氨基-3-羟基苯甲酸代谢的酶被纯化并进行了特征分析。当在含有NAD+和来自于4-氨基-3-羟基苯甲酸的细胞提取物的反应混合物中使用2-羟基穆康酸6-半醛作为底物时,4-草酰克罗通酸、2-氧戊-4-烯酸和4-羟基-2-氧戊酸被鉴定为中间产物,而丙酮酸被鉴定为最终产物。提出了10d株对4-氨基-3-羟基苯甲酸的完整代谢途径。10d株通过脱氢途径代谢由4-氨基-3-羟基苯甲酸衍生的2-羟基穆康酸6-半醛,而不是通过水解途径。这种提议的代谢途径与2-氨基酚的改良元断裂途径以及之前报道的甲基和氯衍生物的途径有显著不同。