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Original Research ARTICLE

Front. Bioeng. Biotechnol. | doi: 10.3389/fbioe.2020.00707

An (R)-Selective Transaminase from Thermomyces stellatus: Stabilizing the Tetrameric Form Provisionally accepted The final, formatted version of the article will be published soon. Notify me

  • 1University of Nottingham, United Kingdom
  • 2University of Milan, Italy
  • 3Johnson Matthey (United Kingdom), United Kingdom
  • 4University of Bern, Switzerland

The identification and 3D structural characterization of a homologue of the (R)-selective transaminase (RTA) from Aspergillus terreus (AtRTA), from the thermotolerant fungus Thermomyces stellatus (TsRTA) is here reported. The thermostability of TsRTA (40% retained activity after 7 days at 40°C) was initially attributed to its tetrameric form in solution, however subsequent studies of AtRTA revealed it also exists predominantly as a tetramer yet, at 40°C, it is inactivated within 48 hours. The engineering of a cysteine residue to promote disulfide bond formation across the dimer-dimer interface stabilized both enzymes, with TsRTA_G205C retaining almost full activity after incubation at 50 °C for 7 days. Thus, the role of this mutation was elucidated and the importance of stabilizing the tetramer for overall stability of RTAs is highlighted. TsRTA accepts the common amine donors (R)-methylbenzylamine, isopropylamine, and d-alanine as well as aromatic and aliphatic ketones and aldehydes.

Keywords: Biocatalysis, Amino transferase, crystal structure, Chiral amine, thermostability Words: 5679; Figures/Tables: 7

Received: 06 Apr 2020; Accepted: 05 Jun 2020.

Copyright: © 2020 Heckmann, Gourlay, Dominguez and Paradisi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Francesca Paradisi, University of Bern, Bern, Switzerland, francesca.paradisi@dcb.unibe.ch