Directed OmniChange evolution converts P450 BM3 into an alkyltrimethylammonium hydroxylase
Yu Ji, Alan Maurice Mertens, Christoph Gertler, Sallama Fekiri, Merve Keser, Daniel F. Sauer, Kilian E. C. Smith, and Ulrich Schwaneberg*, Chemistry - A European Journal, 2018, doi:10.1002/chem.201803806
Reengineering of the P450 BM3 substrate specificity towards the hydroxylation of CTAB by OmniChange multi-site mutagenesis method
Bolaform surfactants are a novel class of compounds with a wide range of industrial and technical applications. Bolaform surfactants are capable of forming of very small micelles and therefore are more effective than contemporary surfactants.
However, their production is expensive and involves the use of strong acids and large amounts of solvents. An alternative green synthesis route is the direct hydroxylation through monooxygenases as performed in nature.
In this study, the OmniChange multi-site mutagenesis method was applied for reengineering of the P450 BM3 substrate specificity towards the hydroxylation of CTAB by simultaneous mutagenesis of four relevant positions. Improved variants were identified in a two-step screening system. Then 10 promising P450 BM3 variants were analyzed by HPLC-MS/MS. Four P450 BM3 variants had significantly improved productivities and were kinetically characterized after purification. Interestingly all four variants were capable to di-hydroxylate CTAB and coupling efficiency up to 92.5% were obtained.
Notably, di-hydroxylation products of CTAB with bolaform surfactant properties have for the first time been produced. Bolaform surfactants are biodegradable and sustainable surfactants that offer excellent solubility properties and novel possibilities for drug delivery and/or compound formulations. Additionally, the two-step screening system proved to be efficient to boost coupling efficiency and can likely be used in many other P450 evolution campaigns to generate robust P450 catalysts. This work was funded by the China Scholarship Council, No. 201608080082.
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