In vitro phosphorylation of acetylcholinesterase at non-consensus protein kinase A sites enhances the rate of acetylcholine hydrolysis.

Grifman, M; Arbel, A; Ginzberg, D; Glick, D; Elgavish, S; Shaanan, B; Soreq, H

Grifman, M; Arbel, A; Ginzberg, D; Glick, D; Elgavish, S; Shaanan, B; Soreq, H.

Afiliación

Grifman M; Department of Biological Chemistry, Institute of Life Sciences, Hebrew University of Jerusalem, Israel.

Brain Res Mol Brain Res ; 51(1-2): 179-87, 1997 Nov.

Article en En | MEDLINE | ID: mdl-9427520

RESUMEN

Here, we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) but not casein kinase II or protein kinase C phosphorylates recombinant human acetylcholinesterase (AChE) in vitro. This enhances acetylthiocholine hydrolysis up to 10-fold as compared to untreated AChE, while leaving unaffected the enzyme's affinity for this substrate and for various active and peripheral site inhibitors. Alkaline phosphatase treatment enhanced the electrophoretic migration, under denaturing conditions, of part of the AChE proteins isolated from various mammalian sources and raised the isoelectric point of some of the treated AChE molecules, indicating that part of the AChE molecules are also phosphorylated in vivo. Enhancement of acetylthiocholine hydrolysis also occurred with Torpedo AChE, which has no consensus motif for PKA phosphorylation. Further, mutating the single PKA site in human AChE (threonine-249) did not prevent this enhancement, suggesting that in both cases it was due to phosphorylation at non-consensus sites. In vivo suppression of the acetylcholine hydrolyzing activity of AChE and consequent impairment in cholinergic neurotransmission occur under exposure to both natural and pharmacological compounds, including organophosphate and carbamate insecticides and chemical warfare agents. Phosphorylation of AChE may possibly offer a rapid feedback mechanism that can compensate for impairments in cholinergic neurotransmission, modulating the hydrolytic activity of this enzyme and enabling acetylcholine hydrolysis to proceed under such challenges.

Asunto(s)

Acetilcolina/metabolismo; Acetilcolinesterasa/química; Acetilcolinesterasa/metabolismo; Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo; Conformación Proteica; Acetiltiocolina/metabolismo; Animales; Encéfalo/enzimología; Bovinos; Clonación Molecular; Secuencia de Consenso; Proteínas Quinasas Dependientes de AMP Cíclico/química; Eritrocitos/enzimología; Escherichia coli; Humanos; Hidrólisis; Cinética; Sustancias Macromoleculares; Modelos Moleculares; Mutagénesis Sitio-Dirigida; Fosforilación; Reacción en Cadena de la Polimerasa; Proteínas Recombinantes/química; Proteínas Recombinantes/metabolismo; Serina; Treonina

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Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Acetilcolinesterasa / Conformación Proteica / Acetilcolina / Proteínas Quinasas Dependientes de AMP Cíclico Límite: Animals / Humans Idioma: En Revista: Brain Res Mol Brain Res Asunto de la revista: BIOLOGIA MOLECULAR / CEREBRO Año: 1997 Tipo del documento: Article País de afiliación: Israel Pais de publicación: Países Bajos

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