title: The binding site of the V-ATPase inhibitor apicularen is in the vicinity of those for bafilomycin and archazolid.
abstract: The investigation of V-ATPases as potential therapeutic drug targets and hence of their specific inhibitors is a promising approach in osteoporosis and cancer treatment because the occurrence of these diseases is interrelated to the function of the V-ATPase. Apicularen belongs to the novel inhibitor family of the benzolactone enamides, which are highly potent but feature the unique characteristic of not inhibiting V-ATPases from fungal sources. In this study we specify, for the first time, the binding site of apicularen within the membrane spanning V(O) complex. By photoaffinity labeling using derivatives of apicularen and of the plecomacrolides bafilomycin and concanamycin, each coupled to (14)C-labeled 4-(3-trifluoromethyldiazirin-3-yl)benzoic acid, we verified that apicularen binds at the interface of the V(O) subunits a and c. The binding site is in the vicinity to those of the plecomacrolides and of the archazolids, a third family of V-ATPase inhibitors. Expression of subunit c homologues from Homo sapiens and Manduca sexta, both species sensitive to benzolactone enamides, in a Saccharomyces cerevisiae strain lacking the corresponding intrinsic gene did not transfer this sensitivity to yeast. Therefore, the binding site of benzolactone enamides cannot be formed exclusively by subunit c. Apparently, subunit a substantially contributes to the binding of the benzolactone enamides.
authors: Fachbereich Biologie/Chemie, Abteilung Tierphysiologie, Universität Osnabrück, Barbarastrasse 11, 49069 Osnabrück, German.
authors: Christin
authors: C
authors: Osteresch
authors: Tobias
authors: T
authors: Bender
authors: Stephanie
authors: S
authors: Grond
authors: Paultheo
authors: P
authors: von Zezschwitz
authors: Brigitte
authors: B
authors: Kunze
authors: Rolf
authors: R
authors: Jansen
authors: Markus
authors: M
authors: Huss
authors: Helmut
authors: H
authors: Wieczorek
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D018942:Macrolides / Q000737:chemistry* / Q000494:pharmacology; D018402:Manduca; D008968:Molecular Conformation; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D013844:Thiazoles / Q000737:chemistry* / Q000494:pharmacology; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000737:chemistry
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D004791:Enzyme Inhibitors; D018942:Macrolides; D013844:Thiazoles; C117813:apicularen A; C519727:archazolid A; C057620:bafilomycin A; C076477:concanamycin F; D025262:Vacuolar Proton-Translocating ATPases