1-Naphthylamine (1NA), which is harmful to human and aquatic animals, has been used widely in the manufacturing of dyes, pesticides, and rubber antioxidants. Nevertheless, little is known about its environmental behavior and no bacteria have been reported to use it as the growth substrate. Herein, we describe a pathway for 1NA degradation in isolate Pseudomonas sp. strain JS3066, determine the structure and mechanism of the enzyme NpaA1 that catalyzes the initial reaction, and reveal how the pathway evolved. From genetic and enzymatic analysis, a cluster of 5 genes encoding a dioxygenase system was determined to be responsible for the initial steps in 1NA degradation through glutamylation of 1NA. The γ-glutamylated 1NA was subsequently oxidized to 1,2-dihydroxynaphthalene which was further degraded by the well-established pathway of naphthalene degradation via catechol. Enzymatic analysis showed that NpaA1 catalyzed conversion of various anilines and naphthylamine derivatives. Structural and biochemical studies of NpaA1 revealed that the broad substrate specificity of NpaA1 is due to a large hydrophobic pocket, which is different from type I glutamine synthetase (GSI). The findings enhance understanding of degrading polycyclic aromatic amines, and will also enable the application of bioremediation at naphthylamine contaminated sites.

中文翻译：

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1-萘胺生物降解途径的发现揭示了一种催化 1-萘胺谷氨酰化的酶

1-萘胺（1NA）对人类和水生动物有害，广泛用于制造染料、农药和橡胶抗氧化剂。然而，人们对其环境行为知之甚少，也没有报道称细菌使用它作为生长基质。在此，我们描述了分离假单胞菌中 1NA 降解的途径。菌株JS3066，确定了催化初始反应的酶NpaA1的结构和机制，并揭示了该途径是如何进化的。根据遗传和酶分析，编码双加氧酶系统的 5 个基因簇被确定负责通过 1NA 谷氨酰化降解 1NA 的初始步骤。γ-谷氨酰化的 1NA 随后被氧化为 1,2-二羟基萘，并通过邻苯二酚的萘降解途径进一步降解。酶分析表明NpaA1催化多种苯胺和萘胺衍生物的转化。NpaA1 的结构和生化研究表明，NpaA1 的广泛底物特异性是由于其具有较大的疏水口袋，这与 I 型谷氨酰胺合成酶 (GSI) 不同。这些发现增强了对多环芳香胺降解的理解，也将使生物修复在萘胺污染场地的应用成为可能。