INHIBITION OF AMINOGLYCOSIDE ANTIBIOTIC-RESISTANCE ENZYMES BY PROTEIN-KINASE INHIBITORS

Bacterial resistance to the aminoglycoside antibiotics is manifested p rimarily through the expression of enzymes which covalently modify the se drugs, One important mechanism of aminoglycoside modification is th rough ATP-dependent O-phosphorylation, catalyzed by a family of aminog lycoside kinases, The structure of one of these kinases, APH(3')-IIIa has recently been determined by x-ray crystallography, and the general fold is strikingly similar to eukaryotic protein kinases (Hon, W. C., McKay, G. A. Thompson, P. R., Sweet, R. M., Yang, D. S. C., Wright, G . D., and Berghuis, A. M. (1997) Cell 89, 887-895), Based on this simi larity, we have examined the effect of known inhibitors of eukaryotic protein kinases on two aminoglycoside kinases, APH(3')-IIIa and the en zyme AAC(6')-APH(2 '') which also exhibits acetyl-CoA-dependent aminog lycoside modification activity, We report that several known protein k inase inhibitors are also good inhibitors of aminoglycoside kinases, C ompounds belonging to the isoquinolinesulfonamide group are especially effective in this regard, giving competitive inhibition in the microm olar range with respect to ATP and noncompetitive inhibition versus th e aminoglycoside substrate, This study provides the basis for future a minoglycoside kinase inhibitor design and for the development of compo unds which could reverse antibiotic resistance in the clinic.