Applying Pairwise Combinations of Amino Acid Mutations for Sorting Out Highly Efficient Glucosylation Tools for Chemo-Enzymatic Synthesis of Bacterial Oligosaccharides

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• 作者：Elise Champion ; Fr茅d茅ric Gu茅rin ; Claire Moulis ; Sophie Barbe ; Thu Hoai Tran ; Sandrine Morel ; Karine Descroix ; Pierre Monsan ; Lionel Mourey ; Laurence A. Mulard ; Samuel Tranier ; Magali Remaud-Sim茅on ; Isabelle Andr茅
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：November 14, 2012
• 年：2012
• 卷：134
• 期：45
• 页码：18677-18688
• 全文大小：559K
• 年卷期：v.134,no.45(November 14, 2012)
• ISSN：1520-5126

文摘

Iterative saturation mutagenesis and combinatorial active site saturation focused on vicinal amino acids were used to alter the acceptor specificity of amylosucrase from Neisseria polysaccharea, a sucrose-utilizing 伪-transglucosidase, and sort out improved variants. From the screening of three semirational sublibraries accounting in total for 20鈥?00 variants, we report here the isolation of three double mutants of N. polysaccharea amylosucrase displaying a spectacular specificity enhancement toward both sucrose, the donor substrate, and the allyl 2-acetamido-2-deoxy-伪-d-glucopyranoside acceptor as compared to the wild-type enzyme. Such levels of activity improvement have never been reported before for this class of carbohydrate-active enzymes. X-ray structure of the best performing enzymes supported by molecular dynamics simulations showed local rigidity of the 鈭? subsite as well as flexibility of loops involved in active site topology, which both account for the enhanced catalytic performances of the mutants. The study well illustrates the importance of taking into account the local conformation of catalytic residues as well as protein dynamics during the catalytic process, when designing enzyme libraries.