The identification and 3D structural characterization of a homolog 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 h. 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.

An (R)-Selective Transaminase From Thermomyces stellatus: Stabilizing the Tetrameric Form / C.M. Heckmann, L.J. Gourlay, B. Dominguez, F. Paradisi. - In: FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY. - ISSN 2296-4185. - 8(2020 Jul), pp. 707.1-707.13. [10.3389/fbioe.2020.00707]

An (R)-Selective Transaminase From Thermomyces stellatus: Stabilizing the Tetrameric Form

Gourlay L. J.;
2020-07

Abstract

The identification and 3D structural characterization of a homolog 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 h. 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.
amino transferase; biocatalysis; chiral amine; crystal structure; enzyme characterization; enzyme engineering; quaternary structure; thermostability
Settore BIO/10 - Biochimica
FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/776991
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