6k5m
From Proteopedia
The crystal structure of a serotonin N-acetyltransferase from Oryza Sativa (Rice)
Structural highlights
Function[SNAT1_ORYSJ] Catalyzes the N-acetylation of serotonin into N-acetylserotonin, the penultimate step in the synthesis of melatonin (PubMed:22998587, PubMed:24134674, PubMed:27121038). Catalyzes in vitro the N-acetylation of tryptamine to produce N-acetyltryptamine, 5-methoxytryptamine to produce melatonin and tyramine to produce N-acetyltyramine (PubMed:27121038). Acetyltransferase required for geminivirus infection and systemic spread (By similarity).[UniProtKB:Q7X9V3][1] [2] [3] Publication Abstract from PubMedSerotonin 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. Structural and Molecular Dynamics Analysis of Plant Serotonin N-Acetyltransferase Reveal an Acid/Base-Assisted Catalysis in Melatonin Biosynthesis.,Liao L, Zhou Y, Xu Y, Zhang Y, Liu X, Liu B, Chen X, Guo Y, Zeng Z, Zhao Y Angew Chem Int Ed Engl. 2021 May 17;60(21):12020-12026. doi:, 10.1002/anie.202100992. Epub 2021 Apr 7. PMID:33682300[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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