Functional characterization of tobacco (Nicotiana benthamiana) serotonin N-acetyltransferases (NbSNAT1 and NbSNAT2)

Functional analysis of tobacco SNAT genes

  • Kyoungwhan Back Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
  • Lee Hyoung Yool Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
  • Hwang Ok Jin Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of Korea
DOI: https://doi.org/10.32794/mr112500109
Keywords: melatonin, N-acetylserotonin, 5-methoxytryptamine, serotonin N-acetyltransferase (SNAT), tobacco

Abstract

Nicotiana benthamiana (tobacco) is an important dicotyledonous model plant; however, no serotonin N-acetyltransferases (SNATs) have been characterized in tobacco. In this study, we identified, cloned, and characterized the enzyme kinetics of two SNAT genes from N. benthamiana, NbSNAT1 and NbSNAT2. The substrate affinity (Km) and maximum reaction rate (Vmax) for NbSNAT1 were 579 µM and 136 pkat/mg protein for serotonin, and 945 µM and 298 pkat/mg protein for 5-methoxytryptamine, respectively. Similarly, the Km and Vmax values for NbSNAT2 were 326 µM and 26 pkat/mg protein for serotonin, and 872 µM and 92 pkat/mg protein for 5-methoxytryptamine, respectively. Moreover, we found that NbSNAT1 and NbSNAT2 localized to chloroplasts, similar to SNAT proteins from other plant species. The activities of the NbSNAT proteins were not affected by melatonin feedback inhibition in vitro. Finally, transgenic tobacco plants overexpressing either NbSNAT1 or NbSNAT2 did not exhibit increased melatonin levels, possibly due to the expression of catabolic enzymes. Generating transgenic tobacco plants with downregulated NbSNAT expression would provide further insight into the functional role of melatonin in tobacco plants.

 


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Published
2021-12-31
How to Cite
[1]
Back, K., Hyoung Yool, L. and Ok Jin, H. 2021. Functional characterization of tobacco (Nicotiana benthamiana) serotonin N-acetyltransferases (NbSNAT1 and NbSNAT2). Melatonin Research. 4, 4 (Dec. 2021), 507-521. DOI:https://doi.org/https://doi.org/10.32794/mr112500109.
Issue
Vol 4 No 4 (2021): Melatonin Research
Section
Research Articles
DOI
https://doi.org/10.32794/mr112500109
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