Egebo L A, Nielsen S V, Jochimsen B U
Department of Molecular Biology and Plant Physiology, University of Aarhus, Denmark.
J Bacteriol. 1991 Aug;173(15):4897-901. doi: 10.1128/jb.173.15.4897-4901.1991.
Some strains of Bradyrhizobium japonicum have the ability to catabolize indole-3-acetic acid (IAA). Examination of this catabolism in strain 110 by in vivo experiments has revealed an enzymatic activity catalyzing the degradation of IAA and 5-hydroxy-indole-3-acetic acid. The activity requires addition of the substrates for induction and is oxygen dependent. The highest activity is obtained when the concentration of inducer is 0.2 mM. Spectrophotometric data are consistent with the suggestion that the indole ring is broken during degradation of IAA. We hypothesize that the enzyme catalyzes an oxygen-consuming opening of the indole ring analogous to the one catalyzed by tryptophan 2,3-dioxygenase. The pattern of metabolite usage by known tryptophan-auxotrophic mutants and studies of metabolites by high-performance liquid chromatography indicate that anthranilic acid is a terminal degradation product in the proposed pathway.
某些日本慢生根瘤菌菌株具有分解吲哚 - 3 - 乙酸（IAA）的能力。通过体内实验对110菌株中的这种分解代谢进行检测，发现了一种催化IAA和5 - 羟基吲哚 - 3 - 乙酸降解的酶活性。该活性需要添加底物来诱导，并且依赖于氧气。当诱导剂浓度为0.2 mM时可获得最高活性。分光光度数据与IAA降解过程中吲哚环被破坏的推测一致。我们假设该酶催化吲哚环的耗氧开环反应，类似于色氨酸2,3 - 双加氧酶催化的反应。已知色氨酸营养缺陷型突变体的代谢物利用模式以及高效液相色谱对代谢物的研究表明，邻氨基苯甲酸是所提出途径中的终末降解产物。
