Crystal structure of the dopamine N-acetyltransferase-acetyl-CoA complex provides insights into the catalytic mechanismCheng, K.C., Liao, J.N., Lyu, P.C.
(2012) Biochem J 446: 395-404
- PubMed: 22716280
- DOI: 10.1042/BJ20120520
- Primary Citation of Related Structures:
- PubMed Abstract:
The daily cycle of melatonin biosynthesis in mammals is regulated by AANAT (arylalkylamine N-acetyltransferase; EC 18.104.22.168), making it an attractive target for therapeutic control of abnormal melatonin production in mood and sleep disorders. Drosoph ...
The daily cycle of melatonin biosynthesis in mammals is regulated by AANAT (arylalkylamine N-acetyltransferase; EC 22.214.171.124), making it an attractive target for therapeutic control of abnormal melatonin production in mood and sleep disorders. Drosophila melanogaster Dat (dopamine N-acetyltransferase) is an AANAT. Until the present study, no insect Dat structure had been solved, and, consequently, the structural basis for its acetyl-transfer activity was not well understood. We report in the present paper the high-resolution crystal structure for a D. melanogaster Dat-AcCoA (acetyl-CoA) complex obtained using one-edge (selenium) single-wavelength anomalous diffraction. A binding study using isothermal titration calorimetry suggested that the cofactor bound to Dat first before substrate. Examination of the complex structure and a substrate-docked model indicated that Dat contains a novel AANAT catalytic triad. Site-directed mutagenesis, kinetic studies and pH-rate profiles confirmed that Glu(47), Ser(182) and Ser(186) were critical for catalysis. Collectively, the results of the present study suggest that Dat possesses a specialized active site structure dedicated to a catalytic mechanism.
Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 30013, Taiwan.