ABSTRACT
Activity of the aminoglycoside phosphotransferase APH(3')-Ia leads to resistance to aminoglycoside antibiotics in pathogenic Gram-negative bacteria, and contributes to the clinical obsolescence of this class of antibiotics. One strategy to rescue compromised antibiotics such as aminoglycosides is targeting the enzymes that confer resistance with small molecules. We demonstrated previously that ePK (eukaryotic protein kinase) inhibitors could inhibit APH enzymes, owing to the structural similarity between these two enzyme families. However, limited structural information of enzyme-inhibitor complexes hindered interpretation of the results. In addition, cross-reactivity of compounds between APHs and ePKs represents an obstacle to their use as aminoglycoside adjuvants to rescue aminoglycoside antibiotic activity. In the present study, we structurally and functionally characterize inhibition of APH(3')-Ia by three diverse chemical scaffolds, anthrapyrazolone, 4-anilinoquinazoline and PP (pyrazolopyrimidine), and reveal distinctions in the binding mode of anthrapyrazolone and PP compounds to APH(3')-Ia compared with ePKs. Using this observation, we identify PP derivatives that select against ePKs, attenuate APH(3')-Ia activity and rescue aminoglycoside antibiotic activity against a resistant Escherichia coli strain. The structures described in the present paper and the inhibition studies provide an important opportunity for structure-based design of compounds to target aminoglycoside phosphotransferases for inhibition, potentially overcoming this form of antibiotic resistance.
Subject(s)
Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/antagonists & inhibitors , Drug Design , Drug Resistance, Bacterial/drug effects , Kanamycin Kinase/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Acinetobacter baumannii/enzymology , Anthracenes/chemistry , Anthracenes/metabolism , Anthracenes/pharmacology , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Binding Sites , Escherichia coli/drug effects , Escherichia coli/growth & development , Escherichia coli/metabolism , Isoenzymes/antagonists & inhibitors , Isoenzymes/chemistry , Isoenzymes/genetics , Isoenzymes/metabolism , Kanamycin/chemistry , Kanamycin/metabolism , Kanamycin/pharmacology , Kanamycin Kinase/chemistry , Kanamycin Kinase/genetics , Kanamycin Kinase/metabolism , Microbial Sensitivity Tests , Molecular Conformation , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Pyrazoles/chemistry , Pyrazoles/metabolism , Pyrazoles/pharmacology , Pyrimidines/chemistry , Pyrimidines/metabolism , Pyrimidines/pharmacology , Quinazolines/chemistry , Quinazolines/metabolism , Quinazolines/pharmacology , Recombinant Proteins/antagonists & inhibitors , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Structure-Activity RelationshipABSTRACT
Palladium complexes incorporating ligands based on a 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phosphaadamantanyl scaffold were used to catalyze the arylation of ethyl cyanoacetate, malononitrile, and various ketones. The products from these reactions can be elaborated to substituted ß-arylethylamines and used in microwave-assisted Pictet-Spengler reactions. The protocol developed is suitable for the synthesis of libraries of substituted isoquinolines.
