Skip to Main content Skip to Navigation
Journal articles

Computer-Aided Engineering of a Transglycosylase for the Glucosylation of an Unnatural Disaccharide of Relevance for Bacterial Antigen Synthesis

Abstract : The exploration of chemo-enzymatic routes to complex carbohydrates has been hampered by the lack of appropriate enzymatic tools having the substrate specificity for new reactions. Here, we used a computer-aided design framework to guide the construction of a small, diversity-controlled library of amino acid sequences of an α-transglucosylase, the sugar binding subsites of which were re-engineered to enable the challenging 1,2-cis-glucosylation of a partially protected β-linked disaccharide allyl (2-deoxy-2-trichloroacetamido-β-d-glucopyranosyl)-(1→2)-α-l-rhamnopyranoside, a potential intermediate in the synthesis of Shigella flexneri cell-surface oligosaccharides. The target disaccharide is not recognized by the parental wild-type enzyme and exhibits a molecular structure very distinct from that of the natural α-(1→4)-linked acceptor. A profound reshaping of the binding pocket had thus to be performed. Following the selection of 23 amino acid positions from the first shell, mutations were sampled using RosettaDesign leading to a subset of 1515 designed sequences, which were further analyzed by determining the amino acid variability among the designed sequences and their conservation in evolutionary-related enzymes. A combinatorial library of 2.7 × 104 variants was finally designed, constructed, and screened. One mutant showing the desired and totally new specificity was successfully identified from this first round of screening. Impressively, this mutant contained seven substitutions in the first shell of the active site leading to a drastic reshaping of the catalytic pocket without significantly perturbing the original specificity for sucrose donor substrate. This work illustrates how computer-aided approaches can undoubtedly offer novel opportunities to design tailored carbohydrate-active enzymes of interest for glycochemistry or synthetic glycobiology.
Complete list of metadatas

https://hal-pasteur.archives-ouvertes.fr/pasteur-02043360
Contributor : Laurence Mulard <>
Submitted on : Wednesday, February 20, 2019 - 11:30:45 PM
Last modification on : Wednesday, May 27, 2020 - 10:25:35 AM

Identifiers

Citation

Alizee Verges, Emmanuelle Cambon, Sophie Barbe, Stéphane Salamone, Yann Le Guen, et al.. Computer-Aided Engineering of a Transglycosylase for the Glucosylation of an Unnatural Disaccharide of Relevance for Bacterial Antigen Synthesis. ACS Catalysis, American Chemical Society, 2015, 5 (2), pp.1186-1198. ⟨10.1021/cs501288r⟩. ⟨pasteur-02043360⟩

Share

Metrics

Record views

266