Visualization of Substrate Binding and Translocation by the ATP-dependent Protease, ClpXP

Mol Cell. 2000 Dec;6(6):1515-21. doi: 10.1016/s1097-2765(00)00148-9.


Binding and internalization of a protein substrate by E. coli ClpXP was investigated by electron microscopy. In sideviews of ATP gamma S-stabilized ClpXP complexes, a narrow axial channel was visible in ClpX, surrounded by protrusions on its distal surface. When substrate lambda O protein was added, extra density attached to this surface. Upon addition of ATP, this density disappeared as lambda O was degraded. When ATP was added to proteolytically inactive ClpXP-lambda O complexes, the extra density transferred to the center of ClpP and remained inside ClpP after separation from ClpX. We propose that substrates of ATP-dependent proteases bind to specific sites on the distal surface of the ATPase, and are subsequently unfolded and translocated into the internal chamber of the protease.

MeSH terms

  • ATPases Associated with Diverse Cellular Activities
  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphatases / ultrastructure*
  • Adenosine Triphosphate / analogs & derivatives*
  • Adenosine Triphosphate / metabolism
  • Bacteriophage lambda
  • Binding Sites
  • Dimerization
  • Endopeptidase Clp
  • Escherichia coli / enzymology*
  • Escherichia coli Proteins*
  • Image Processing, Computer-Assisted
  • Macromolecular Substances
  • Microscopy, Electron
  • Models, Molecular
  • Molecular Chaperones
  • Polylysine / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Serine Endopeptidases / chemistry
  • Serine Endopeptidases / metabolism*
  • Serine Endopeptidases / ultrastructure*
  • Viral Proteins / metabolism
  • Viral Proteins / ultrastructure


  • Escherichia coli Proteins
  • Macromolecular Substances
  • Molecular Chaperones
  • O protein, Bacteriophage lambda
  • Viral Proteins
  • Polylysine
  • adenosine 5'-O-(3-thiotriphosphate)
  • Adenosine Triphosphate
  • Serine Endopeptidases
  • ClpXP protease, E coli
  • Endopeptidase Clp
  • Adenosine Triphosphatases
  • ClpX protein, E coli
  • ATPases Associated with Diverse Cellular Activities