Loop engineering of aryl sulfotransferase B for improving catalytic performance in regioselective sulfation
Yu Ji, Shohana Islam, Haiyang Cui, Gaurao V. Dhoke, Mehdi D. Davari, Alan M. Mertens, Ulrich Schwaneberg, Catalysis Science & Technology, 2020, 10, 2369-2377
Reengineering of loop12 and loop 13 of aryl sulfotransferase B yielded variant with high sulfate transfer efficiency up to 94%.
Catechol sulfates act in our body as important antioxidants and often have anti-inflammatory properties. This study focuses on reengineering of loop 12 and loop 13 of aryl sulfotransferase B from Desulfitobacterium hafniense in order to improve the sulfate transfer efficiency of six catechols. The obtained aryl sulfotransferase B variants were generated in a KnowVolution campaign using the random mutagenesis method SeSaM and the multi-site saturation method OmniChange. The catalytic activity and catalytic efficiency of the final variant were improved for all six investigated catechols when compared to the wild type (e.g., 13.6-fold improvement of catalytic activity for 3-bromocatechol). HPLC-MS analysis confirmed the improved sulfate stoichiometry of aryl sulfotransferase B variant with a transfer efficiency up to 94% for 3-methylcatechol in comparison to 24% for the wild type. A molecular understanding of the improved sulfation activity of the variant was achieved through molecular docking studies and electron effects of catechol substituents were analyzed by Hammett equation. Enzymatic sulfation of catechol as well as substituted catechols by aryl sulfotransferases opens up an environmentally friendly route for chemo- and / or regioselective sulfation of valuable compounds, such as mycamine, sodium picosulfate, and minoxidil sulfate.