6UQW

Crystal structure of ChoE in complex with acetate and thiocholine

Summary for 6UQW

• Entry DOI: 10.2210/pdb6uqw/pdb
• Descriptor: ChoE, ACETATE ION, 2-(TRIMETHYLAMMONIUM)ETHYL THIOL, ... (5 entities in total)
• Functional Keywords: esterase, acetylcholine, hydrolase
• Biological source: Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)
• Total number of polymer chains: 2
• Total formula weight: 63657.48

Authors

Pham, V.D.,Shi, R. (deposition date: 2019-10-21, release date: 2020-05-13, Last modification date: 2024-10-09)

Primary citation

Pham, V.D.,To, T.A.,Gagne-Thivierge, C.,Couture, M.,Lague, P.,Yao, D.,Picard, M.E.,Lortie, L.A.,Attere, S.A.,Zhu, X.,Levesque, R.C.,Charette, S.J.,Shi, R.
Structural insights into the putative bacterial acetylcholinesterase ChoE and its substrate inhibition mechanism.
J.Biol.Chem., 295:8708-8724, 2020

PubMed Abstract: Mammalian acetylcholinesterase (AChE) is well-studied, being important in both cholinergic brain synapses and the peripheral nervous systems and also a key drug target for many diseases. In contrast, little is known about the structures and molecular mechanism of prokaryotic acetylcholinesterases. We report here the structural and biochemical characterization of ChoE, a putative bacterial acetylcholinesterase from Analysis of WT and mutant strains indicated that ChoE is indispensable for growth with acetylcholine as the sole carbon and nitrogen source. The crystal structure of ChoE at 1.35 Å resolution revealed that this enzyme adopts a typical fold of the SGNH hydrolase family. Although ChoE and eukaryotic AChEs catalyze the same reaction, their overall structures bear no similarities constituting an interesting example of convergent evolution. Among Ser-38, Asp-285, and His-288 of the catalytic triad residues, only Asp-285 was not essential for ChoE activity. Combined with kinetic analyses of WT and mutant proteins, multiple crystal structures of ChoE complexed with substrates, products, or reaction intermediate revealed the structural determinants for substrate recognition, snapshots of the various catalytic steps, and the molecular basis of substrate inhibition at high substrate concentrations. Our results indicate that substrate inhibition in ChoE is due to acetate release being blocked by the binding of a substrate molecule in a nonproductive mode. Because of the distinct overall folds and significant differences of the active site between ChoE and eukaryotic AChEs, these structures will serve as a prototype for other prokaryotic acetylcholinesterases.

PubMed: 32371400
DOI: 10.1074/jbc.RA119.011809

Experimental method

X-RAY DIFFRACTION (1.65 Å)