The structural basis of ordered substrate binding by serotonin N-acetyltransferase: enzyme complex at 1.8 A resolution with a bisubstrate analog.Hickman, A.B., Namboodiri, M.A., Klein, D.C., Dyda, F.
(1999) Cell 97: 361-369
- PubMed: 10319816
- DOI: https://doi.org/10.1016/s0092-8674(00)80745-x
- Primary Citation of Related Structures:
- PubMed Abstract:
Serotonin N-acetyltransferase, a member of the GNAT acetyltransferase superfamily, is the penultimate enzyme in the conversion of serotonin to melatonin, the circadian neurohormone. Comparison of the structures of the substrate-free enzyme and the complex with a bisubstrate analog, coenzyme A-S-acetyltryptamine, demonstrates that acetyl coenzyme A (AcCoA) binding is accompanied by a large conformational change that in turn leads to the formation of the serotonin-binding site. The structure of the complex also provides insight into how the enzyme may facilitate acetyl transfer. A water-filled channel leading from the active site to the surface provides a pathway for proton removal following amine deprotonation. Furthermore, structural and mutagenesis results indicate an important role for Tyr-168 in catalysis.
Laboratory of Developmental Neurobiology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-0560, USA.