title: Effects of 39 Compounds on Calmodulin-Regulated Adenylyl Cyclases AC1 and Bacillus anthracis Edema Factor.
abstract: Adenylyl cyclases (ACs) catalyze the conversion of ATP into the second messenger cAMP. Membranous AC1 (AC1) is involved in processes of memory and learning and in muscle pain. The AC toxin edema factor (EF) of Bacillus anthracis is involved in the development of anthrax. Both ACs are stimulated by the eukaryotic Ca(2+)-sensor calmodulin (CaM). The CaM-AC interaction could constitute a potential target to enhance or impair the AC activity of AC1 and EF to intervene in above (patho)physiological mechanisms. Thus, we analyzed the impact of 39 compounds including typical CaM-inhibitors, an anticonvulsant, an anticholinergic, antidepressants, antipsychotics and Ca(2+)-antagonists on CaM-stimulated catalytic activity of AC1 and EF. Compounds were tested at 10 μM, i.e., a concentration that can be reached therapeutically for certain antidepressants and antipsychotics. Calmidazolium chloride decreased CaM-stimulated AC1 activity moderately by about 30%. In contrast, CaM-stimulated EF activity was abrogated by calmidazolium chloride and additionally decreased by chlorpromazine, felodipine, penfluridol and trifluoperazine by about 20-40%. The activity of both ACs was decreased by calmidazolium chloride in the presence and absence of CaM. Thus, CaM-stimulated AC1 activity is more insensitive to inhibition by small molecules than CaM-stimulated EF activity. Inhibition of AC1 and EF by calmidazolium chloride is largely mediated via a CaM-independent allosteric mechanism.
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Hannover, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Lübker
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Hannover, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Seifert
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors / Q000494:pharmacology*; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000942:Antigens, Bacterial; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors*; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D061987:Sf9 Cells; D054852:Small Molecule Libraries / Q000494:pharmacology*; D018411:Spodoptera
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D002492:Central Nervous System Depressants; D054852:Small Molecule Libraries; C030325:anthrax toxin; D000262:Adenylyl Cyclases; C106670:adenylyl cyclase 1