Functional consequences and structural interpretation of mutations of human choline acetyltransferase

Xin Ming Shen, Thomas O. Crawford, Joan Brengman, Gyula Acsadi, Susan Iannaconne, Emin Karaca, Chaouky Khoury, Jean K. Mah, Shimon Edvardson, Zeljko Bajzer, David Rodgers, Andrew G. Engel

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Choline acetyltransferase (ChAT; EC catalyzes synthesis of acetylcholine from acetyl-CoA (AcCoA) and choline in cholinergic neurons. Mutations in CHAT cause potentially lethal congenital myasthenic syndromes associated with episodic apnea (ChAT-CMS). Here, we analyze the functional consequences of 12 missense and one nonsense mutations of CHAT in 11 patients. Nine of the mutations are novel. We examine expression of the recombinant missense mutants in Bosc 23 cells, determine their kinetic properties and thermal stability, and interpret the functional effects of 11 mutations in the context of the atomic structural model of human ChAT. Five mutations (p.Trp421Ser, p.Ser498Pro, p.Thr553Asn, p.Ala557Thr, and p.Ser572Trp) reduce enzyme expression to less than 50% of wild-type. Mutations with severe kinetic effects are located in the active-site tunnel (p.Met202Arg, p.Thr553Asn, and p.Ala557Thr) or adjacent to the substrate binding site (p.Ser572Trp), or exert their effect allosterically (p.Trp421Ser and p.Ile689Ser). Two mutations with milder kinetic effects (p.Val136Met and p.Ala235Thr) are also predicted to act allosterically. One mutation (p.Thr608Asn) below the nucleotide binding site of CoA enhances dissociation of AcCoA from the enzyme-substrate complex. Two mutations introducing a proline residue into an α-helix (p.Ser498Pro and p.Ser704Pro) impair the thermal stability of ChAT.

Original languageEnglish
Pages (from-to)1259-1267
Number of pages9
JournalHuman Mutation
Issue number11
StatePublished - Nov 2011


  • CHAT
  • Choline acetyltransferase
  • Congenital myasthenic syndrome
  • Kinetics
  • Thermal stability

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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