Data Entry: Please note that the research database will be replaced by UNIverse by the end of October 2023. Please enter your data into the system https://universe-intern.unibas.ch. Thanks
Proximity-accelerated chemical coupling reaction in the benzodiazepine-binding site of gamma-aminobutyric acid type A receptors: superposition of different allosteric modulators
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
Proximity-accelerated chemical coupling reaction in the benzodiazepine-binding site of gamma-aminobutyric acid type A receptors: superposition of different allosteric modulators
Journal
Journal of Biological Chemistry
Volume
282
Number
36
Pages / Article-Number
26316-25
Abstract
Benzodiazepines are widely used drugs. They exert sedative/hypnotic, anxiolytic, muscle relaxant, and anticonvulsant effects and act through a specific high affinity binding site on the major inhibitory neurotransmitter receptor, the gamma-aminobutyric acid type A (GABA(A)) receptor. Ligands of the benzodiazepine-binding site are classified into three groups depending on their mode of action: positive and negative allosteric modulators and antagonists. To rationally design ligands of the benzodiazepine site in different isoforms of the GABA(A) receptor, we need to understand the relative positioning and overlap of modulators of different allosteric properties. To solve these questions, we used a proximity-accelerated irreversible chemical coupling reaction. GABA(A) receptor residues thought to reside in the benzodiazepine-binding site were individually mutated to cysteine and combined with a cysteine-reactive benzodiazepine site ligand. Direct apposition of reaction partners is expected to lead to a covalent reaction. We describe here such a reaction of predominantly alpha(1)H101C and also three other mutants (alpha(1)G157C, alpha(1)V202C, and alpha(1)V211C) with an Imid-NCS derivative in which a reactive isothiocyanate group (-NCS) replaces the azide group (-N(3)) in the partial negative allosteric modulator Ro15-4513. Our results show four contact points of imidazobenzodiazepines with the receptor, alpha(1)H101C being shared by classical benzodiazepines. Taken together with previous data, a similar orientation of these ligands within the benzodiazepine-binding pocket may be proposed.
Publisher
American Society for Biochemistry and Molecular Biology
