Fluorinated Aminoglycosides and Their Mechanistic Implication for Aminoglycoside 3'-Phosphotransferases from Gram-Negative Bacteria

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• 作者：Choonkeun Kim ; Jalal Haddad ; Sergei B. Vakulenko ; Samy O. Meroueh ; Yan Wu ; Honggao Yan ; and Shahriar Mobashery
• 刊名：Biochemistry
• 出版年：2004
• 出版时间：March 9, 2004
• 年：2004
• 卷：43
• 期：9
• 页码：2373 - 2383
• 全文大小：146K
• 年卷期：v.43,no.9(March 9, 2004)
• ISSN：1520-4995

文摘

Aminoglycoside 3'-phosphotransferases [APH(3')s] are important bacterial resistance enzymesfor aminoglycoside antibiotics. These enzymes phosphorylate the 3'-hydroxyl of these antibiotics, a reactionthat inactivates the drug. A series of experiments were carried out to shed light on the details of theturnover chemistry by these enzymes. Quench-flow pre-steady-state kinetic analyses of the reactions ofGram-negative APH(3') types Ia and IIa with kanamycin A, neamine, and their respective difluorinatedanalogues 4'-deoxy-4',4'-difluorokanamycin A and 4'-deoxy-4',4'-difluoroneamine were carried out, inconjunction with measurements of thio effect and viscosity studies. The fluorinated analogues were shownto be severely impaired as substrates for these enzymes. The magnitude of the effect of the impairmentof the fluorinated substrates was in the same range as when the D198A mutant APH(3')-Ia was studiedwith nonfluorinated substrates. Residue 198 is the proposed active site base that promotes theaminoglycoside hydroxyl for phosphorylation. These findings collectively argue that the Gram-negativeAPH(3')s show significant nucleophilic participation in the transition state for the phosphate transferreaction.