1
|
Wegner U, Matthes F, von Wirén N, Lemke I, Bode R, Vorbrodt HM, Rauter M, Kunze G. Enhancing a Sphaerobacter thermophilus ω-transaminase for kinetic resolution of β- and γ-amino acids. AMB Express 2023; 13:117. [PMID: 37864072 PMCID: PMC10589169 DOI: 10.1186/s13568-023-01623-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 10/03/2023] [Indexed: 10/22/2023] Open
Abstract
Sphaerobacter thermophilus synthesizes an ω-transaminase (ω-TA) that allows the production of enantiomerically pure β-amino acids. To obtain ω-TA variants with a higher activity and more favorable properties for industrial use, we modified critical amino acid residues either in the catalytic center or in a previously proposed signature motif critical for aromatic β-amino acid ω-TAs. Seventeen different variants of this enzyme were generated and their activity was examined with four β-amino acids and one γ-amino acid, and compared with the wildtype's activity. Among all variants, seven showed up to ninefold higher activity with at least one of the tested substrates. For most of these seven variants, the temperature optimum was even lower as in the wild type enzyme, with keeping a high temperature stability, making them more valuable for industrial purposes. Our results indicate that for the production of enantiomerically pure β-amino acids replacement of critical amino acid residues in the proposed signature motif of ω-TAs is a more effective strategy than modifying their catalytic center. Another finding was, that the proposed motif is not only suitable for aromatic amino acid ω-TAs, because some of the variants have a higher activity with β-alanine or β-leucine than with aromatic β-amino acids.
Collapse
Affiliation(s)
- Uwe Wegner
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Seeland, OT Gatersleben, Germany
| | - Falko Matthes
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Seeland, OT Gatersleben, Germany
| | - Nicolaus von Wirén
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Seeland, OT Gatersleben, Germany
| | - Ina Lemke
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Seeland, OT Gatersleben, Germany
| | - Rüdiger Bode
- Institute of Microbiology, University of Greifswald, Jahnstr. 15, 17487, Greifswald, Germany
| | - H-Matthias Vorbrodt
- Orgentis Chemicals GmbH, Bahnhofstr. 3-5, 06466, Seeland, OT Gatersleben, Germany
| | - Marion Rauter
- Orgentis Chemicals GmbH, Bahnhofstr. 3-5, 06466, Seeland, OT Gatersleben, Germany
| | - Gotthard Kunze
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Seeland, OT Gatersleben, Germany.
| |
Collapse
|
2
|
Crystal structure of a novel putative sugar isomerase from the psychrophilic bacterium Paenibacillus sp. R4. Biochem Biophys Res Commun 2021; 585:48-54. [PMID: 34784551 DOI: 10.1016/j.bbrc.2021.11.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 11/07/2021] [Indexed: 11/20/2022]
Abstract
Sugar isomerases (SIs) catalyze the reversible conversion of aldoses to ketoses. A novel putative SI gene has been identified from the genome sequence information on the psychrophilic bacterium Paenibacillus sp. R4. Here, we report the crystal structure of the putative SI from Paenibacillus sp. R4 (PbSI) at 2.98 Å resolution. It was found that the overall structure of PbSI adopts the triose-phosphate isomerase (TIM) barrel fold. PbSI was also identified to have two heterogeneous metal ions as its cofactors at the active site in the TIM barrel, one of which was confirmed as a Zn ion through X-ray anomalous scattering and inductively coupled plasma mass spectrometry analysis. Structural comparison with homologous SI proteins from mesophiles, hyperthermophiles, and a psychrophile revealed that key residues in the active site are well conserved and that dimeric PbSI is devoid of the extended C-terminal region, which tetrameric SIs commonly have. Our results provide novel structural information on the cold-adaptable SI, including information on the metal composition in the active site.
Collapse
|