title: A Pseudomonas aeruginosa PAO1 acetylcholinesterase is encoded by the PA4921 gene and belongs to the SGNH hydrolase family.
abstract: Through the use of molecular and biochemical experiments and bioinformatic tools, this work demonstrates that the PA4921 gene of the Pseudomonas aeruginosa PAO1 genome is a gene responsible for cholinesterase (ChoE) activity. Similar to the acetylcholinesterase (AchE) of Zea mays, this ChoE belongs to the SGNH hydrolase family. In mature ChoE, i.e., without a signal peptide, (18)Ser, (78)Gly, (127)N, and (268)H are conserved aminoacyl residues. Acetylthiocholine (ATC) and propionylthiocholine (PTC) are substrates of this enzyme, but butyrylcholine is an inhibitor. The enzyme also catalyzes the hydrolysis of the artificial esters p-nitrophenyl propionate (pNPP) and p-nitrophenyl butyrate (pNPB) but with lower catalytic efficiency with respect to ATC or PTC. The second difference is that pNPP and pNPB did not produce inhibition at high substrate concentrations, as occurred with ATC and PTC. These differences plus preliminary biochemical and kinetic studies with alkylammonium compounds led us to propose that this enzyme is an acetylcholinesterase (AchE) or propionylcholinesterase. Studies performed with the purified recombinant enzyme indicated that the substrate saturation curves and the catalytic mechanism are similar to those properties described for mammalian AchEs. Therefore, the results of this work suggest that the P. aeruginosa ChoE is an AchE that may also be found in Pseudomonas fluorescens.
authors.affiliation: Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
authors.forename: Diego G
authors.initials: DG
authors.lastname: Sánchez
authors.forename: Lisandro H
authors.initials: LH
authors.lastname: Otero
authors.forename: C Magdalena
authors.initials: CM
authors.lastname: Hernández
authors.forename: Ana L
authors.initials: AL
authors.lastname: Serra
authors.forename: Sergio
authors.initials: S
authors.lastname: Encarnación
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Domenech
authors.forename: Angela T
authors.initials: AT
authors.lastname: Lisa
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D000122:Acetylthiocholine / Q000378:metabolism; D002794:Choline / Q000031:analogs & derivatives / Q000378:metabolism; D017124:Conserved Sequence; D004791:Enzyme Inhibitors / Q000378:metabolism; D006867:Hydrolases / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D010802:Phylogeny; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013860:Thiocholine / Q000031:analogs & derivatives / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; C009063:propionylthiocholine; C017100:butyrylcholine; D000122:Acetylthiocholine; D013860:Thiocholine; D006867:Hydrolases; D000110:Acetylcholinesterase; D002794:Choline