Aminoglycoside acetyltransferase

Enzymes transferring an acetyl moiety to one specific of several amino-groups of the aminocyclitol-aminoglycoside antibiotics (e.g. gentamicin, amikacin, kanamycin) are called aminoglycoside acetyltransferases... 

Genes encoding 3-iV-aminoglycoside acetyltransferases confer resistance to aminoglycosides... 

Gene encoding an aminoglycoside acetyltransferase confers reduced susceptibility to ciprofloxacin and norfloxacin... 

Unit, [tg/mL Kan, kanamycin S. aureus, Staphylococcus aureus P. aeruginosa, Pseudomonas aeruginosa AAC, aminoglycoside acetyltransferase ANT, aminoglycoside nucleotidyltransferase Perm, mutant, mutant strain impermeable to kanamycin A and B. 

Fig. 13.5 Structure of kanamycin B showing system of ring numbering and sites of action of some aminoglycosidemodifying enzymes. AAC, aminoglycoside acetyltransferase ANT, aminoglycoside nucleotidyltransferase and APH, aminoglycoside phosphotransferase.

These depend on the fact that bacterial resistance to aminoglycosides (Chapter 13), such as gentamicin, tobramycin, amikacin, netilmicin, streptomycin, spectinomycin, etc. and chloramphenicol is frequently associated with the presence of specific enzymes (often coded for by transmissible plasmids), which either acetylate, adenylylate or phosphory-late the antibiotics, thereby rendering them inactive (Chapter 13). Aminoglycosides may be susceptible to attack by aminoglycoside acetyltransferases... 

Figure 18 Enzymatic inactivation of ciprofloxacin by N-acetylation catalyzed by the aminoglycoside acetyltransferase AAC(6 )-lb enzyme.

Figure 3 First-generation bisubstrate analog inhibitors of aminoglycoside acetyltransferases.

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