The Aminoglycoside N-Acetyltransferases (AAC) family of enzymes is composed of four major subclasses based on regiospecificity of aminoglycoside acetyltransfer: AAC(6 ), AAC(2 ), AAC(1), and AAC(3). These enzymes are found in both Gram-positive and Gram-negative bacteria and generally present a very broad aminoglycoside resistance profile. The AACs form the largest family of aminoglycoside resistance enzymes and are dominated by the large number of AAC(6 ) homologs, many of which are chromosomally encoded.
The crystal structure of AACs enzymes
reveal their similarity to one another and their affiliation with the
GCN5-related N-acetyltransferases (GNAT) superfamily . The family is defined
by a common 3D-folding pattern formed around an acyl-CoA binding pocket. The AAC
enzymes share little amino acid sequence homology with other members of the GNAT
superfamily such as the histone acetyltransferases. However, they share the
folding motifs that define this family: an N-terminal α-helix, a central
antiparallel β-sheet, and a four stranded mixed b-sheet
flanked by two a-helices at the C-terminus.
1. Vetting, M. W.; de Carvalho LP, S. d. C.; Yu, M.; Hegde, S. S.; Magnet, S.; Roderick, S. L.; Blanchard, J. S. Arch. Biochem. Biophys. 2005, 433, 212.
2. Robicsek, A.; Strahilevitz, J.; Jacoby, G. A.; Macielag, M.; Abbanat, D.; Park, C. H.; Bush, K.; Hooper, D. C. Nat. Med. 2006, 12, 83.
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