Expression Patterns and Functional Analysis of Three <i>SmTAT</i> Genes Encoding Tyrosine Aminotransferases in <i>Salvia miltiorrhiza</i>
Tyrosine aminotransferase (TAT, E.C. 2.6.1.5) is a pyridoxal phosphate-dependent aminotransferase that is widely found in living organisms. It catalyzes the transfer of the amino group on tyrosine to α-ketoglutarate to produce 4-hydroxyphenylpyruvic acid (4-HPP) and is the first enzyme for tyrosine...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-10-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/24/21/15575 |
| Summary: | Tyrosine aminotransferase (TAT, E.C. 2.6.1.5) is a pyridoxal phosphate-dependent aminotransferase that is widely found in living organisms. It catalyzes the transfer of the amino group on tyrosine to α-ketoglutarate to produce 4-hydroxyphenylpyruvic acid (4-HPP) and is the first enzyme for tyrosine degradation. Three <i>SmTATs</i> have been identified in the genome of <i>Salvia miltiorrhiza</i> (a model medicinal plant), but their information is very limited. Here, the expression profiles of the three <i>SmTAT</i> genes (<i>SmTAT1</i>, <i>SmTAT2</i>, and <i>SmTAT3</i>) were studied. All three genes expressed in different tissues and responded to methyl jasmonate stimuli. <i>Sm</i>TAT proteins are localized in the cytoplasm. The recombinant <i>Sm</i>TATs were subjected to in vitro biochemical properties. All three recombinant enzymes had TAT activities and <i>Sm</i>TAT1 had the highest catalytic activity for tyrosine, followed by <i>Sm</i>TAT3. Also, <i>Sm</i>TAT1 preferred the direction of tyrosine deamination to 4-HPP, while <i>Sm</i>TAT2 preferred transamination of 4-HPP to tyrosine. In parallel, transient overexpression of <i>SmTATs</i> in tobacco leaves revealed that all three <i>Sm</i>TAT proteins catalyzed tyrosine to 4-HPP in vivo, with <i>Sm</i>TAT1 exhibiting the highest enzymatic activity. Overall, our results lay a foundation for the production of tyrosine-derived secondary metabolites via metabolic engineering or synthetic biology in the future. |
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| ISSN: | 1661-6596 1422-0067 |