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Identification of novel thermostable taurine–pyruvate transaminase from Geobacillus thermodenitrificans for chiral amine synthesis

Abstract

ω-Transaminases (ω-TAs) are one of the most popular candidate enzymes in the biosynthesis of chiral amines. Determination of yet unidentified ω-TAs is important to broaden their potential for synthetic application. Taurine–pyruvate TA (TPTA, EC 2.6.1.77) is an ω-TA belonging to class III of TAs. In this study, we cloned a novel thermostable TPTA from Geobacillus thermodenitrificans (TPTAgth) and overexpressed it in Escherichia coli. The enzyme showed the highest activity at pH 9.0 and 65 °C, with remarkable thermostability and tolerance toward organic solvents. Its K M and v max values for taurine were 5.3 mM and 0.28 μmol s−1 mg−1, respectively. Determination of substrate tolerance indicated its broad donor and acceptor ranges for unnatural substrates. Notably, the enzyme showed relatively good activity toward ketoses, suggesting its potential for catalyzing the asymmetric synthesis of chiral amino alcohols. The active site of TPTAgth was identified by performing protein sequence alignment, three-dimensional structure simulation, and coenzyme pyridoxamine phosphate docking. The protein sequence and structure of TPTAgth were similar to those of TAs belonging to the 3N5M subfamily. Its active site was found to be its special large pocket and substrate tunnel. In addition, TPTAgth showed a unique mechanism of sulfonate/α-carboxylate recognition contributed by Arg163 and Gln160. We also determined the protein sequence fingerprint of TPTAs in the 3N5M subfamily, which involved Arg163 and Gln160 and seven additional residues from 413 to 419 and lacked Phe/Tyr22, Phe85, and Arg409.

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Acknowledgments

This work was funded by the National Natural Science Funds of China (Grant No. 21406069).

Conflict of interest

Mr. Yujie Chen declares that he has no conflict of interest.

Dr. Dong Yi declares that he has no conflict of interest.

Ms. Shuiqin Jiang declares that she has no conflict of interest.

Prof. Dr. Dongzhi Wei declares that he has no conflict of interest.

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This article does not contain any studies with human participants or animals performed by any of the authors.

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Correspondence to Dong Yi or Dongzhi Wei.

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Yujie Chen and Dong Yi contributed equally to this work.

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Fig. S1

Nucleotide sequence of TPTAgth. The nucleotide sequence of TPTAgth has been deposited in the GenBank database under accession number KT719298. (PDF 99 kb)

Fig. S2

SDS-PAGE analysis of purified recombinant TPTAgth. (PDF 151 kb)

Fig. S3

Protein sequence alignment of TPTAgth. ω-TApde: ω-TA from Paracoccus denitrificans (UniProt ID: A1B956), ω-TAvfl: ω-TA from Vibrio fluvialis (UniProt ID: F2XBU9), ω-TAcvi: ω-TA from Chromobacterium violaceum (UniProt ID: Q7NWG4), ω-TAppu: ω-TA from Pseudomonas putida (UniProt ID: P28269), 3N5M: PDB item 3N5M, TPTAban: TPTA from Bacillus anthracis (UniProt ID: Q81SL2), TPTAbsu: TPTA from Bacillus subtilis (UniProt ID: P33189), TPTAbwa: TPTA from Bilophila wadsworthia (UniProt ID: Q9APM5), TPTApde: TPTA from Paracoccus denitrificans (UniProt ID: A1B9Z3), TPTArpo: TPTA from Ruegeria pomeroyi (UniProt ID: Q5LVM7). The sequence alignment was achieved by NTI Vector software 11.5 (ThermoFischer, USA). The identical residues are marked as *. The key residues are highlighted in bold. Arg163, Gln160 and the additional loop between α15 and β13 are highlighted in grey. (PDF 143 kb)

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Chen, Y., Yi, D., Jiang, S. et al. Identification of novel thermostable taurine–pyruvate transaminase from Geobacillus thermodenitrificans for chiral amine synthesis. Appl Microbiol Biotechnol 100, 3101–3111 (2016). https://doi.org/10.1007/s00253-015-7129-5

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  • DOI: https://doi.org/10.1007/s00253-015-7129-5

Keywords

  • Taurine–pyruvate transaminase
  • ω-Transaminase
  • Biocatalysis
  • Thermostable transaminase
  • Chiral amine