Biochemical Characterization of a Recombinant UDP-glucosyltransferase from Rice and Enzymatic Production of Deoxynivalenol-3-O-β-d-glucoside

Toxins

Herbert Michlmayr³  Alexandra Malachová²  Elisabeth Varga²  Jana Kleinová²  Marc Lemmens¹  Sean Newmister⁴  Ivan Rayment⁴  Franz Berthiller²  Gerhard Adam³ 

[1] Biotechnology in Plant Production, Department IFA-Tulln, BOKU, Konrad Lorenz Str. 20, 3430 Tulln, Austria; E-Mail:;Christian Doppler Laboratory for Mycotoxin Metabolism and Center for Analytical Chemistry, Department of Agrobiotechnology (IFA-Tulln), BOKU, Konrad Lorenz Str. 20, 3430 Tulln, Austria; E-Mails:;Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Str. 24, 3430 Tulln, Austria; E-Mail:;Department of Biochemistry, University of Wisconsin, 433 Babcock Dr., Madison, WI 53706, USA; E-Mails:

关键词: masked mycotoxin;    glycosylation;    sucrose synthase;    UDP-glucose recycling;    Fusarium;   

DOI  :  10.3390/toxins7072685

来源: mdpi

【 摘 要 】

Glycosylation is an important plant defense mechanism and conjugates of Fusarium mycotoxins often co-occur with their parent compounds in cereal-based food and feed. In case of deoxynivalenol (DON), deoxynivalenol-3-O-β-d-glucoside (D3G) is the most important masked mycotoxin. The toxicological significance of D3G is not yet fully understood so that it is crucial to obtain this compound in pure and sufficient quantities for toxicological risk assessment and for use as an analytical standard. The aim of this study was the biochemical characterization of a DON-inactivating UDP-glucosyltransferase from rice (OsUGT79) and to investigate its suitability for preparative D3G synthesis. Apparent Michaelis constants (K_m) of recombinant OsUGT79 were 0.23 mM DON and 2.2 mM UDP-glucose. Substrate inhibition occurred at DON concentrations above 2 mM (K_i = 24 mM DON), and UDP strongly inhibited the enzyme. Cu²⁺ and Zn²⁺ (1 mM) inhibited the enzyme completely. Sucrose synthase AtSUS1 was employed to regenerate UDP-glucose during the glucosylation reaction. With this approach, optimal conversion rates can be obtained at limited concentrations of the costly co-factor UDP-glucose. D3G can now be synthesized in sufficient quantity and purity. Similar strategies may be of interest to produce β-glucosides of other toxins.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.