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Publication Abstract from PubMed

alpha5 subunit-containing gamma-aminobutyric acid type A (GABA(A)) receptors represent a promising drug target for neurological and neuropsychiatric disorders. Altered expression and function contributes to neurodevelopmental disorders such as Dup15q and Angelman syndromes, developmental epilepsy and autism. Effective drug action without side effects is dependent on both alpha5-subtype selectivity and the strength of the positive or negative allosteric modulation (PAM or NAM). Here we solve structures of drugs bound to the alpha5 subunit. These define the molecular basis of binding and alpha5 selectivity of the beta-carboline, methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), type II benzodiazepine NAMs, and a series of isoxazole NAMs and PAMs. For the isoxazole series, each molecule appears as an 'upper' and 'lower' moiety in the pocket. Structural data and radioligand binding data reveal a positional displacement of the upper moiety containing the isoxazole between the NAMs and PAMs. Using a hybrid molecule we directly measure the functional contribution of the upper moiety to NAM versus PAM activity. Overall, these structures provide a framework by which to understand distinct modulator binding modes and their basis of alpha5-subtype selectivity, appreciate structure-activity relationships, and empower future structure-based drug design campaigns.

The molecular basis of drug selectivity for alpha5 subunit-containing GABA(A) receptors.,Kasaragod VB, Malinauskas T, Wahid AA, Lengyel J, Knoflach F, Hardwick SW, Jones CF, Chen WN, Lucas X, El Omari K, Chirgadze DY, Aricescu AR, Cecere G, Hernandez MC, Miller PS Nat Struct Mol Biol. 2023 Oct 30. doi: 10.1038/s41594-023-01133-1. PMID:37903907^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.