Biologically Important Conformations of Aminoglycoside Antibiotics Bound to an Aminoglycoside 3‘-Phosphotransferase as Determined by Transferred Nuclear Overhauser Effect Spectroscopy

Publisher Website
Google Scholar
Abstract
NMR spectroscopy has been used to study the interaction of aminoglycoside antibiotics with an aminoglycoside antibiotic 3‘-phosphotransferase [APH(3‘)-IIIa]. APH(3‘)-IIIa is an enterococcal enzyme that is responsible for the ATP-dependent O-phosphorylation of a broad range of aminoglycoside antibiotics. The NMR method of transferred nuclear Overhauser effect spectroscopy (TRNOESY) was used to detect intra- and inter-ring NOEs for butirosin A and amikacin in their respective ternary complexes with APH(3‘)-IIIa and ATP. NOE-derived distance constraints were used in energy minimization and dynamics routines to yield enzyme-bound structures for butirosin A. These structures suggest that the 2,6-diamino-2,6-dideoxy-d-glucose and d-xylose rings have restricted motions and are in a stacking arrangement. The TRNOE spectra for amikacin suggest that the 6-amino-6-deoxy-d-glucose ring is flexible when the antibiotic is bound to APH(3‘)-IIIa. The 15N resonances of butirosin A were assigned and the pKa values of the amino groups of butirosin A and amikacin were determined by 15N NMR spectroscopy. The N3 amino groups of butirosin A and amikacin have lowered pKa values, which is attributed to the (S)-4-amino-2-hydroxybutyryl (AHB) group of the antibiotics. This work provides an insight into the geometrical and electrostatic nature of aminoglycoside antibiotics bound to a modifying enzyme and will provide a basis for the design of inhibitors of APH(3‘)-IIIa.

This publication has 10 references indexed in Scilit: