7DAI

The crystal structure of a serotonin N-acetyltransferase from Oryza Sativa

Summary for 7DAI

• Entry DOI: 10.2210/pdb7dai/pdb
• Descriptor: Serotonin N-acetyltransferase 1, chloroplastic (2 entities in total)
• Functional Keywords: n-acetyltransferase, transferase
• Biological source: Oryza sativa subsp. japonica (Rice)
• Total number of polymer chains: 3
• Total formula weight: 55521.42

Authors

Zhou, Y.Z.,Liao, L.J.,Tang, T.,Guo, Y.,Liu, X.K.,Liu, B.,Zhao, Y.C. (deposition date: 2020-10-16, release date: 2021-09-22, Last modification date: 2023-11-29)

Primary citation

Liao, L.,Zhou, Y.,Xu, Y.,Zhang, Y.,Liu, X.,Liu, B.,Chen, X.,Guo, Y.,Zeng, Z.,Zhao, Y.
Structural and Molecular Dynamics Analysis of Plant Serotonin N-Acetyltransferase Reveal an Acid/Base-Assisted Catalysis in Melatonin Biosynthesis.
Angew.Chem.Int.Ed.Engl., 60:12020-12026, 2021

PubMed Abstract: Serotonin N-acetyltransferase (SNAT) is the key rate-limiting enzyme in melatonin biosynthesis. It mediates melatonin biosynthesis in plants by using serotonin and 5-methoxytryptamine (5-MT), but 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 the crystal structures of plant SNAT in the apo and binary/ternary complex forms with acetyl-CoA (AcCoA), serotonin, and 5-MT. OsSNAT exhibits a unique enzymatically active dimeric fold not found in the known structures of arylalkylamine N-acetyltransferase (AANAT) family. The key residues W188, D189, D226, N220, and Y233 located around the active pocket are important in catalysis, 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.

PubMed: 33682300
DOI: 10.1002/anie.202100992

Experimental method

X-RAY DIFFRACTION (2.3 Å)