Directed Evolution of a Tryptophan 2,3-Dioxygenase for the Diastereoselective Monooxygenation of Tryptophans.

Yanxin Wei, Chen Lu, Shengsheng Jiang, Yanyan Zhang, Qiuchun Li, Wen-Ju Bai, Xiqing Wang

Angewandte Chemie (International ed. in English) 2020 Feb 17

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Herein, we report an engineered enzyme that can monooxygenate unprotected tryptophan into the corresponding 3a-hydroxyhexahydropyrrolo[2,3-b]indole-2-carboxylic acid (HPIC) in a single, scalable step with excellent turnover number and diastereoselectivity. Taking advantage of directed evolution, we analyzed the stepwise oxygen-insertion mechanism of tryptophan 2,3-dioxygenases, and transformed tryptophan 2,3-dioxygenase from Xanthomonas campestris into a monooxygenase for oxidative cyclization of tryptophans. It was revealed that residue F51 is vital in determining the product ratio of HPIC to N'-formylkynurenine. Our reactions and purification procedures use no organic solvents, resulting in an eco-friendly method to prepare HPICs for further applications. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Citation

Yanxin Wei, Chen Lu, Shengsheng Jiang, Yanyan Zhang, Qiuchun Li, Wen-Ju Bai, Xiqing Wang. Directed Evolution of a Tryptophan 2,3-Dioxygenase for the Diastereoselective Monooxygenation of Tryptophans. Angewandte Chemie (International ed. in English). 2020 Feb 17;59(8):3043-3047