Tyrian purple, mainly composed of 6,6'-dibromoindigo (6BrIG), is an ancient dye extracted from sea snails and was recently demonstrated as a biocompatible semiconductor material. However, its synthesis remains limited due to uncharacterized biosynthetic pathways and the difficulty of regiospecific bromination. Here, we introduce an effective 6BrIG production strategy in Escherichia coli using tryptophan 6-halogenase SttH, tryptophanase TnaA and flavin-containing monooxygenase MaFMO. Since tryptophan halogenases are expressed in highly insoluble forms in E. coli, a flavin reductase (Fre) that regenerates FADH₂ for the halogenase reaction was used as an N-terminal soluble tag of SttH. A consecutive two-cell reaction system was designed to overproduce regiospecifically brominated precursors of 6BrIG by spatiotemporal separation of bromination and bromotryptophan degradation. These approaches led to 315.0 mg l⁻¹ 6BrIG production from tryptophan and successful synthesis of regiospecifically dihalogenated indigos. Furthermore, it was demonstrated that 6BrIG overproducing cells can be directly used as a bacterial dye.

Tyrian Purple 主要由 6,6'-二溴靛蓝 (6BrIG) 组成，是一种从海螺中提取的古老染料，最近被证明是一种生物相容的半导体材料。然而，由于未表征的生物合成途径和区域特异性溴化的困难，其合成仍然有限。在这里，我们使用色氨酸 6-卤素酶 SttH、色氨酸酶 TnaA 和含黄素的单加氧酶 MaFMO在大肠杆菌中介绍了一种有效的 6BrIG 生产策略。由于色氨酸卤化酶在大肠杆菌中以高度不溶的形式表达，因此一种可再生 FADH _{2的黄素还原酶 (Fre)}用于卤化酶反应的用作 SttH 的 N 端可溶性标签。设计了一个连续的双细胞反应系统，通过溴化和溴色氨酸降解的时空分离，过量产生区域特异性溴化的 6BrIG 前体。这些方法导致从色氨酸生产 315.0 mg l ^-1 6BrIG 并成功合成区域特异性二卤化靛蓝。此外，证明了过量产生 6BrIG 的细胞可以直接用作细菌染料。