Backbone resonance assignments of dopamine N-acetyltransferase in free and cofactor-bound states.

Abstract

Dopamine N-acetyltransferase (Dat), belonging to the GCN5-related N-acetyltransferase (GNAT) superfamily, is an arylalkylamine N-acetyltransferase (AANAT) that is involved in insects neurotransmitter inactivation and the development of insect cuticle sclerotization. By using the cofactor acetyl coenzyme A (Ac-CoA) as an acetyl group donor, Dat produces acetyl-dopamine through the reaction with dopamine. Although AANATs share similar structural features with the GNAT family, they have low sequence identities among insect AANATs (~ 40%) and between insect AANATs and vertebrate AANATs (~ 12%). A common noticed feature in GNATs is the Ac-CoA-binding induced conformational change, and this is important for further selection and catalysis of its substrate. In AANATs, the conformational changes help the sequential binding mechanism. Here, we report the ¹H, ¹³C and ¹⁵N backbone resonance assignments of the 24 kDa Dat from Drosophila melanogaster in the free and Ac-CoA-bound states, and the chemical shift differences revealed a significant conformational change in the α1 region of Dat. These assignments provide a foundation for further investigations of the catalysis and structural regulation of Dat in solution.