title: Analysis of the pi-pi stacking interactions between the aminoglycoside antibiotic kinase APH(3')-IIIa and its nucleotide ligands.
abstract: A key contact in the active site of an aminoglycoside phosphotransferase enzyme (APH(3')-IIIa) is a pi-pi stacking interaction between Tyr42 and the adenine ring of bound nucleotides. We investigated the prevalence of similar Tyr-adenine contacts and found that many different protein systems employ Tyr residues in the recognition of the adenine ring. The geometry of these stacking interactions suggests that electrostatics play a role in the attraction between these aromatic systems. Kinetic and calorimetric experiments on wild-type and mutant forms of APH(3')-IIIa yielded further experimental evidence of the importance of electrostatics in the adenine binding region and suggested that the stacking interaction contributes approximately 2 kcal/mol of binding energy. This type of information concerning the forces that govern nucleotide binding in APH(3')-IIIa will facilitate inhibitor design strategies that target the nucleotide binding site of APH-type enzymes.
authors.affiliation: Antimicrobial Research Centre, Department of Biochemistry, McMaster University, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.
authors.forename: David D
authors.initials: DD
authors.lastname: Boehr
authors.forename: Adam R
authors.initials: AR
authors.lastname: Farley
authors.forename: Gerard D
authors.initials: GD
authors.lastname: Wright
authors.forename: James R
authors.initials: JR
authors.lastname: Cox
mesh_terms: D000225:Adenine; D000244:Adenosine Diphosphate / Q000737:chemistry* / Q000494:pharmacology; D002151:Calorimetry; D004583:Electrons; D019868:Kanamycin Kinase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D011485:Protein Binding; D055672:Static Electricity; D013816:Thermodynamics; D014443:Tyrosine
chemical_list: D008024:Ligands; D014443:Tyrosine; D000244:Adenosine Diphosphate; D019868:Kanamycin Kinase; D000225:Adenine