Evolved Thermostable Transketolase for Stereoselective Two-Carbon Elongation of Non-Phosphorylated Aldoses to Naturally Rare Ketoses

Abstract : We propose an ecofriendly, efficient, stereoselective procedure for the two-carbon elongation of nonphosphorylated aldoses (C4–C6) to the corresponding Cn+2 ketoses (C6–C8) in one step, using hydroxypyruvate (HPA) as a ketol donor substrate and an evolved thermostable transketolase from Geobacillus stearothermophilus (TKgst) as a biocatalyst. Simultaneous site saturation mutagenesis (SSM) at two or three key positions in the TKgst active site yielded efficient variants, L382F/F435Y, R521Y/S385/H462N, and R521V/S385D/H462S, with increased activity compared to wild-type TKgst for conversion of two tetroses (d-threose, l-erythrose), two pentoses (d-xylose, d-ribose), and two hexoses (d-allose, d-glucose), respectively. These six Cn aldoses as acceptor and HPA as donor substrates were transformed by the TKgst variants at 60 °C with practically complete conversion. The corresponding Cn+2 ketoses, including two hexuloses (d-tagatose, l-psicose), two heptuloses (d-altro-heptulose, d-ido-heptulose), and two octuloses (d-glycero-d-ido-octulose, d-glycero-d-altro-octulose) are naturally rare compounds with important biological functions, which were obtained with high diastereoselectivity.
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https://hal.archives-ouvertes.fr/hal-02195534
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Submitted on : Friday, July 26, 2019 - 1:39:49 PM
Last modification on : Saturday, July 27, 2019 - 1:20:15 AM

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Marion Lorillière, Romain Dumoulin, Mélanie L’enfant, Agnès Rambourdin, Vincent Thery, et al.. Evolved Thermostable Transketolase for Stereoselective Two-Carbon Elongation of Non-Phosphorylated Aldoses to Naturally Rare Ketoses. ACS Catalysis, American Chemical Society, 2019, 9 (6), pp.4754-4763. ⟨10.1021/acscatal.9b01339⟩. ⟨hal-02195534⟩

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