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[摘要]：The synthesis of terpenoid glycosides typically uses a chem. strategy since few biocatalysts have been identified that recognize these scaffolds. In this study, a platform of 107 recombinant glycosyltransferases (GTs), comprising the multigene family of small mol. GTs of Arabidopsis thaliana have been screened against a range of model terpenoid acceptors to identify those enzymes with high activity. Twenty-seven GTs are shown to glycosylate a diversity of mono-, sesqui- and diterpenes, such as geraniol, perillyl alc., artemisinic acid and retinoic acid. Certain enzymes showing substantial sequence similarity recognize terpenoids contg. a primary alc., irresp. of the linear or cyclical structure of the scaffold; other GTs glycosylate scaffolds contg. secondary and tertiary alcs.; the carboxyl group of other terpenoids also represents a feature that is recognized by GTs previously known to form glucose esters with many different compds. These data underpin the rapid prediction of potential biocatalysts from GT sequence information. To explore the potential of GTs as biocatalysts, their use for the prodn. of terpenoid glycosides was investigated by using a microbial-based whole-cell biotransformation system capable of regenerating the cofactor, UDP-glucose. A high cell d. fermn. system was shown to produce several hundred milligrams of a model terpenoid, geranyl-glucoside. The activities of the GTs are discussed in relation to their substrate recognition and their utility in biotransformations as a complement or alternative to chem. synthesis. |
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