Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice
A new clade of serotonin <i>N</i>-acetyltransferase (SNAT), the penultimate enzyme in the melatonin biosynthetic pathway, has been reported in the archaeon <i>Thermoplasma volcanium</i>. The closest homolog of archaea SNAT in human was an <i>N</i>-alpha-acetyltran...
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| Format: | Article |
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MDPI AG
2023-01-01
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| Series: | Antioxidants |
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| Online Access: | https://www.mdpi.com/2076-3921/12/2/319 |
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| author | Kyungjin Lee Kyoungwhan Back |
| author_facet | Kyungjin Lee Kyoungwhan Back |
| author_sort | Kyungjin Lee |
| collection | DOAJ |
| description | A new clade of serotonin <i>N</i>-acetyltransferase (SNAT), the penultimate enzyme in the melatonin biosynthetic pathway, has been reported in the archaeon <i>Thermoplasma volcanium</i>. The closest homolog of archaea SNAT in human was an <i>N</i>-alpha-acetyltransferase50 (Naa50). To determine whether human Naa50 (hNaa50) shows SNAT enzyme activity, we chemically synthesized and expressed the <i>hNaa50</i> gene in <i>Escherichia coli</i>, followed by Ni<sup>2+</sup> affinity purification. Purified recombinant hNaa50 showed SNAT activity (<i>K</i><sub>m</sub> and <i>V</i><sub>max</sub> values of 986 μM and 1800 pmol/min/mg protein, respectively). To assess its in vivo function, <i>hNaa50</i> was overexpressed in rice (<i>hNaa50-</i>OE). The transgenic rice plants produced more melatonin than nontransgenic wild-type rice, indicating that <i>hNaa50</i> is functionally coupled with melatonin biosynthesis. Due to its overproduction of melatonin, <i>hNaa50</i>-OE had a higher tolerance against osmotic stress than the wild type. Enhanced expression of the chaperone genes <i>BIP1</i> and <i>CNX</i> in <i>hNaa50</i>-OE plants was responsible for the increased tolerance. It is concluded that <i>hNaa50</i> harbors serotonin <i>N</i>-acetyltransferase enzyme activity in addition to its initial <i>N</i>-alpha-acetyltransferase, suggesting the bifunctionality of the <i>hNaa50</i> enzyme toward serotonin and protein substrates. Consequently, ectopic overexpression of <i>hNaa50</i> in rice enhanced melatonin synthesis, indicating that <i>hNaa50</i> is in fact involved in melatonin biosynthesis. |
| first_indexed | 2024-03-11T09:13:44Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2076-3921 |
| language | English |
| last_indexed | 2024-03-11T09:13:44Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Antioxidants |
| spelling | doaj.art-1762053bf59e42bf80528f8914a9d98a2023-11-16T18:46:30ZengMDPI AGAntioxidants2076-39212023-01-0112231910.3390/antiox12020319Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in RiceKyungjin Lee0Kyoungwhan Back1Department of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of KoreaDepartment of Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 61186, Republic of KoreaA new clade of serotonin <i>N</i>-acetyltransferase (SNAT), the penultimate enzyme in the melatonin biosynthetic pathway, has been reported in the archaeon <i>Thermoplasma volcanium</i>. The closest homolog of archaea SNAT in human was an <i>N</i>-alpha-acetyltransferase50 (Naa50). To determine whether human Naa50 (hNaa50) shows SNAT enzyme activity, we chemically synthesized and expressed the <i>hNaa50</i> gene in <i>Escherichia coli</i>, followed by Ni<sup>2+</sup> affinity purification. Purified recombinant hNaa50 showed SNAT activity (<i>K</i><sub>m</sub> and <i>V</i><sub>max</sub> values of 986 μM and 1800 pmol/min/mg protein, respectively). To assess its in vivo function, <i>hNaa50</i> was overexpressed in rice (<i>hNaa50-</i>OE). The transgenic rice plants produced more melatonin than nontransgenic wild-type rice, indicating that <i>hNaa50</i> is functionally coupled with melatonin biosynthesis. Due to its overproduction of melatonin, <i>hNaa50</i>-OE had a higher tolerance against osmotic stress than the wild type. Enhanced expression of the chaperone genes <i>BIP1</i> and <i>CNX</i> in <i>hNaa50</i>-OE plants was responsible for the increased tolerance. It is concluded that <i>hNaa50</i> harbors serotonin <i>N</i>-acetyltransferase enzyme activity in addition to its initial <i>N</i>-alpha-acetyltransferase, suggesting the bifunctionality of the <i>hNaa50</i> enzyme toward serotonin and protein substrates. Consequently, ectopic overexpression of <i>hNaa50</i> in rice enhanced melatonin synthesis, indicating that <i>hNaa50</i> is in fact involved in melatonin biosynthesis.https://www.mdpi.com/2076-3921/12/2/319archaeahumanNaa50<i>N</i>-acetylserotoninsynthetic genemelatonin |
| spellingShingle | Kyungjin Lee Kyoungwhan Back Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice Antioxidants archaea human Naa50 <i>N</i>-acetylserotonin synthetic gene melatonin |
| title | Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice |
| title_full | Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice |
| title_fullStr | Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice |
| title_full_unstemmed | Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice |
| title_short | Human Naa50 Shows Serotonin <i>N</i>-Acetyltransferase Activity, and Its Overexpression Enhances Melatonin Biosynthesis, Resulting in Osmotic Stress Tolerance in Rice |
| title_sort | human naa50 shows serotonin i n i acetyltransferase activity and its overexpression enhances melatonin biosynthesis resulting in osmotic stress tolerance in rice |
| topic | archaea human Naa50 <i>N</i>-acetylserotonin synthetic gene melatonin |
| url | https://www.mdpi.com/2076-3921/12/2/319 |
| work_keys_str_mv | AT kyungjinlee humannaa50showsserotonininiacetyltransferaseactivityanditsoverexpressionenhancesmelatoninbiosynthesisresultinginosmoticstresstoleranceinrice AT kyoungwhanback humannaa50showsserotonininiacetyltransferaseactivityanditsoverexpressionenhancesmelatoninbiosynthesisresultinginosmoticstresstoleranceinrice |