title: Defining the molecular forces that determine the impact of neomycin on bacterial protein synthesis: importance of the 2'-amino functionality.
abstract: 2-Deoxystreptamine (2-DOS) aminoglycosides exert their antibiotic actions by binding to the A site of the 16S rRNA and interfering with bacterial protein synthesis. However, the molecular forces that govern the antitranslational activities of aminoglycosides are poorly understood. Here, we describe studies aimed at elucidating these molecular forces. In this connection, we compare the bactericidal, antitranslational, and rRNA binding properties of the 4,5-disubstituted 2-DOS aminoglycoside neomycin (Neo) and a conformationally restricted analog of Neo (CR-Neo) in which the 2'-nitrogen atom is covalently conjugated to the 5''-carbon atom. The bactericidal potency of Neo exceeds that of CR-Neo, with this enhanced antibacterial activity reflecting a correspondingly enhanced antitranslational potency. Time-resolved fluorescence anisotropy studies suggest that the enhanced antitranslational potency of Neo relative to that of CR-Neo is due to a greater extent of drug-induced reduction in the mobilities of the nucleotides at positions 1492 and 1493 of the rRNA A site. Buffer- and salt-dependent binding studies, coupled with high-resolution structural information, point to electrostatic contacts between the 2'-amino functionality of Neo and the host rRNA as being an important modulator of 1492 and 1493 base mobilities and therefore antitranslational activities.
authors.affiliation: UMDNJ-Robert Wood Johnson Medical School, Department of Pharmacology, Piscataway, NJ 08854-5635, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Barbieri
authors.forename: Malvika
authors.initials: M
authors.lastname: Kaul
authors.forename: Melanie
authors.initials: M
authors.lastname: Bozza-Hingos
authors.forename: Fang
authors.initials: F
authors.lastname: Zhao
authors.forename: Yitzhak
authors.initials: Y
authors.lastname: Tor
authors.forename: Thomas
authors.initials: T
authors.lastname: Hermann
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Pilch
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009355:Neomycin / Q000494:pharmacology*; D014176:Protein Biosynthesis / Q000187:drug effects*; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D012336:RNA, Ribosomal, 16S; D009355:Neomycin