Structural and Molecular Dynamics Analysis of Plant Serotonin N ‐Acetyltransferase Reveal an Acid/Base‐Assisted Catalysis in Melatonin Biosynthesis
| Autor: | Yucheng Zhao, Youdong Xu, Yuhao Zhang, Xikai Liu, Zhixiong Zeng, Yuanze Zhou, Xinxin Chen, Lijing Liao, Biao Liu, Yan Guo |
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| Rok vydání: | 2021 |
| Předmět: |
Serotonin
AANAT Molecular Dynamics Simulation Crystallography X-Ray 010402 general chemistry Arylalkylamine N-Acetyltransferase 01 natural sciences Catalysis 5-Methoxytryptamine Acetyl Coenzyme A Catalytic Domain Ternary complex Plant Proteins chemistry.chemical_classification 010405 organic chemistry Mutagenesis Hydrogen Bonding Oryza General Chemistry Protein engineering General Medicine 0104 chemical sciences Enzyme chemistry Biochemistry Acetyltransferase Mutation Biocatalysis Mutagenesis Site-Directed Arylalkylamine Function (biology) Protein Binding |
| Zdroj: | Angewandte Chemie. 133:12127-12133 |
| ISSN: | 1521-3757 0044-8249 |
| DOI: | 10.1002/ange.202100992 |
| Popis: | Serotonin N -acetyltransferase (SNAT) is the key rate-limiting enzyme in melatonin biosynthesis. SNAT mediates dual pathways of melatonin biosynthesis in plants by using serotonin and 5-methoxytryptamine (5-MT) as substrates, and a high reaction pH and temperature are essential to its activity. However, little is known of its underlying mechanisms. Herein, we present a detailed reaction mechanism of a SNAT from Oryza sativa through combined structural and molecular dynamics (MD) analysis. We report for the first time the crystal structures of plant SNAT in the apo and binary/ternary complex forms with acetyl-CoA (AcCoA), serotonin, and 5-MT. These structures reveal that Os SNAT exhibits a unique enzymatically active dimeric fold that is not found in all the known structures of arylalkylamine N-acetyltransferase (AANAT) family. The key residues W188, D189, D226, N220, and Y233 located around the active pocket have important role in catalysis which is subsequently confirmed by site-directed mutagenesis. Combined with MD simulations, we hypothesize a novel plausible catalytic mechanism in which D226 and Y233 function as catalytic base and acid during the acetyl-transfer reaction. This work provides a molecular framework for understanding the catalytic mechanisms of plant SNAT and has implications for future protein engineering and biocatalytic applications. |
| Databáze: | OpenAIRE |
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