Antibiotic Binding Drives Catalytic Activation of Aminoglycoside Kinase APH(2″)-Ia

Structure. 2016 Jun 7;24(6):935-45. doi: 10.1016/j.str.2016.04.002. Epub 2016 May 5.


APH(2″)-Ia is a widely disseminated resistance factor frequently found in clinical isolates of Staphylococcus aureus and pathogenic enterococci, where it is constitutively expressed. APH(2″)-Ia confers high-level resistance to gentamicin and related aminoglycosides through phosphorylation of the antibiotic using guanosine triphosphate (GTP) as phosphate donor. We have determined crystal structures of the APH(2″)-Ia in complex with GTP analogs, guanosine diphosphate, and aminoglycosides. These structures collectively demonstrate that aminoglycoside binding to the GTP-bound kinase drives conformational changes that bring distant regions of the protein into contact. These changes in turn drive a switch of the triphosphate cofactor from an inactive, stabilized conformation to a catalytically competent active conformation. This switch has not been previously reported for antibiotic kinases or for the structurally related eukaryotic protein kinases. This catalytic triphosphate switch presents a means by which the enzyme can curtail wasteful hydrolysis of GTP in the absence of aminoglycosides, providing an evolutionary advantage to this enzyme.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoglycosides / metabolism
  • Anti-Bacterial Agents / metabolism*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Crystallography, X-Ray
  • Enzyme Activation
  • Gentamicins / metabolism
  • Guanosine Triphosphate / metabolism
  • Models, Molecular
  • Phosphorylation
  • Phosphotransferases (Alcohol Group Acceptor) / chemistry*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Protein Binding
  • Protein Conformation
  • Staphylococcus aureus / chemistry
  • Staphylococcus aureus / enzymology*


  • Aminoglycosides
  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Gentamicins
  • Guanosine Triphosphate
  • Phosphotransferases (Alcohol Group Acceptor)
  • aminoglycoside 2''-phosphotransferase