Aminoglycoside multiacetylating activity of the enhanced intracellular survival protein from Mycobacterium smegmatis and its inhibition

Biochemistry. 2012 Jun 19;51(24):4959-67. doi: 10.1021/bi3004473. Epub 2012 Jun 5.


The enhanced intracellular survival (Eis) protein improves the survival of Mycobacterium smegmatis (Msm) in macrophages and functions as the acetyltransferase responsible for kanamycin A resistance, a hallmark of extensively drug-resistant (XDR) tuberculosis, in a large number of Mycobacterium tuberculosis (Mtb) clinical isolates. We recently demonstrated that Eis from Mtb (Eis_Mtb) efficiently multiacetylates a variety of aminoglycoside (AG) antibiotics. Here, to gain insight into the origin of substrate selectivity of AG multiacetylation by Eis, we analyzed AG acetylation by Eis_Msm, investigated its inhibition, and compared these functions to those of Eis_Mtb. Even though for several AGs the multiacetylation properties of Eis_Msm and Eis_Mtb are similar, there are three major differences. (i) Eis_Msm diacetylates apramycin, a conformationally constrained AG, which Eis_Mtb cannot modify. (ii) Eis_Msm triacetylates paromomycin, which can be only diacetylated by Eis_Mtb. (iii) Eis_Msm only monoacetylates hygromycin, a structurally unique AG that is diacetylated by Eis_Mtb. Several nonconserved amino acid residues lining the AG-binding pocket of Eis are likely responsible for these differences between the two Eis homologues. Specifically, we propose that because the AG-binding pocket of Eis_Msm is more open than that of Eis_Mtb, it accommodates apramycin for acetylation in Eis_Msm, but not in Eis_Mtb. We also demonstrate that inhibitors of Eis_Mtb that we recently discovered can inhibit Eis_Msm activity. These observations help define the structural origins of substrate preference among Eis homologues and suggest that Eis_Mtb inhibitors may be applied against all pathogenic mycobacteria to overcome AG resistance caused by Eis upregulation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Amino Acid Sequence
  • Aminoglycosides / chemistry
  • Aminoglycosides / metabolism*
  • Bacterial Proteins / antagonists & inhibitors*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Binding, Competitive
  • Catalytic Domain
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Mycobacterium smegmatis*
  • Stereoisomerism
  • Substrate Specificity


  • Aminoglycosides
  • Bacterial Proteins