6K5M

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

Summary for 6K5M

• Entry DOI: 10.2210/pdb6k5m/pdb
• Descriptor: Serotonin N-acetyltransferase 1, chloroplastic (2 entities in total)
• Functional Keywords: serotonin n-acetyltransferase, transferase
• Biological source: Oryza sativa subsp. japonica (Rice)
• Total number of polymer chains: 1
• Total formula weight: 19514.59

Authors

Zhou, Y.Z.,Liao, L.J.,Liu, X.K.,Guo, Y.,Zhao, Y.C.,Zeng, Z.X. (deposition date: 2019-05-29, release date: 2020-06-03, Last modification date: 2024-11-13)

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 (1.793 Å)