Substrate binding and catalytic mechanism of human choline acetyltransferase.
Article Details
- CitationCopy to clipboard
Kim AR, Rylett RJ, Shilton BH
Substrate binding and catalytic mechanism of human choline acetyltransferase.
Biochemistry. 2006 Dec 12;45(49):14621-31.
- PubMed ID
- 17144655 [ View in PubMed]
- Abstract
Choline acetyltransferase (ChAT) catalyzes the synthesis of the neurotransmitter acetylcholine from choline and acetyl-CoA, and its presence is a defining feature of cholinergic neurons. We report the structure of human ChAT to a resolution of 2.2 A along with structures for binary complexes of ChAT with choline, CoA, and a nonhydrolyzable acetyl-CoA analogue, S-(2-oxopropyl)-CoA. The ChAT-choline complex shows which features of choline are important for binding and explains how modifications of the choline trimethylammonium group can be tolerated by the enzyme. A detailed model of the ternary Michaelis complex fully supports the direct transfer of the acetyl group from acetyl-CoA to choline through a mechanism similar to that seen in the serine hydrolases for the formation of an acyl-enzyme intermediate. Domain movements accompany CoA binding, and a surface loop, which is disordered in the unliganded enzyme, becomes localized and binds directly to the phosphates of CoA, stabilizing the complex. Interactions between this surface loop and CoA may function to lower the KM for CoA and could be important for phosphorylation-dependent regulation of ChAT activity.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Choline Choline O-acetyltransferase Protein Humans UnknownSubstrateDetails Choline salicylate Choline O-acetyltransferase Protein Humans UnknownSubstrateDetails - Polypeptides
Name UniProt ID Choline O-acetyltransferase P28329 Details