Structure-Activity Relationships for the Interactions of 2′- and 3′-)-(-Methyl)anthraniloyl-Substituted Purine and Pyrimidine Nucleotides with Mammalian Adenylyl Cyclases

Cibele Pinto (1) , Gerald H. Lushington (2) , Mark Richter (3) , Andreas Gille (1) , Jens Geduhn (4) , Burkhard König (4) , Tung-Chung Mou (5) , Stephen R. Sprang (5) , Roland Seifert (6)

1 Department of Pharmacology and Toxicology
2 KU - University of Kansas [Lawrence]
3 Department of Molecular Biosciences
4 University of Regensburg
5 University of Montana
6 MHH - Medizinische Hochschule Hannover = Hannover Medical School

Membranous adenylyl cyclases (ACs) play a key role in signal transduction and are promising drug targets. In previous studies we showed that 2′,3′-()-(-methylanthraniloyl) (MANT)-substituted nucleotides are potent AC inhibitors. The aim of this study was to provide systematic structure-activity relationships for 21 (M)ANT-substituted nucleotides at the purified catalytic AC subunit heterodimer VC1:IIC2, the VC1:VC1 homodimer and recombinant ACs 1, 2 and 5. (M)ANT-nucleotides inhibited fully activated VC1:IIC2 in the order of affinity for bases hypoxanthine>uracil>cytosine>adenine ∼ guanine >> xanthine. Omission of a hydroxyl group at the 2′ or 3′-position reduced inhibitor potency as did introduction of a γ-thiophosphate group or omission of the γ-phosphate group. Substitution of the MANT-group by an ANT-group had little effect on affinity. Although all nucleotides bound to VC1:IIC2 similarly according to the tripartite pharmacophore model with a site for the base, the ribose, and the phosphate chain, nucleotides exhibited subtle differences in their binding modes as revealed by fluorescence spectroscopy and molecular modelling. MANT-nucleotides also differentially interacted with the VC1:VC1 homodimer as assessed by fluorescence spectroscopy and modelling. Similar structure-activity relationships as for VC1:IIC2 were obtained for recombinant ACs 1, 2 and 5, with AC2 being the least sensitive AC isoform in terms of inhibition. Overall, ACs possess a broad base-specificity with no preference for the "cognate" base adenine as verified by enzyme inhibition, fluorescence spectroscopy and molecular modelling. These properties of ACs are indicative for ligand-specific conformational landscapes that extend to the VC1:VC1 homodimer and should facilitate development of non-nucleotide inhibitors.

Mots clés: Adenylyl Cyclase; MANT-nucleotides; fluorescence spectroscopy; molecular modeling; conformational landscape

Domaines: Pharmacologie

Cibele Pinto, Gerald H. Lushington, Mark Richter, Andreas Gille, Jens Geduhn, et al.. Structure-Activity Relationships for the Interactions of 2′- and 3′-)-(-Methyl)anthraniloyl-Substituted Purine and Pyrimidine Nucleotides with Mammalian Adenylyl Cyclases. Biochemical Pharmacology, 2011, 82 (4), pp.358. ⟨10.1016/j.bcp.2011.05.010⟩. ⟨hal-00718036⟩