Adaptor-dependent degradation of a cell-cycle regulator uses a unique substrate architecture

Structure. 2012 Jul 3;20(7):1223-32. doi: 10.1016/j.str.2012.04.019. Epub 2012 Jun 7.


In Caulobacter crescentus, the ClpXP protease degrades several crucial cell-cycle regulators, including the phosphodiesterase PdeA. Degradation of PdeA requires the response regulator CpdR and signals a morphological transition in concert with initiation of DNA replication. Here, we report the structure of a Per-Arnt-Sim (PAS) domain of PdeA and show that it is necessary for CpdR-dependent degradation in vivo and in vitro. CpdR acts as an adaptor, tethering the amino-terminal PAS domain to ClpXP and promoting recognition of the weak carboxyl-terminal degron of PdeA, a combination that ensures processive proteolysis. We identify sites on the PAS domain needed for CpdR recognition and find that one subunit of the PdeA dimer can be delivered to ClpXP by its partner. Finally, we show that improper stabilization of PdeA in vivo alters cellular behavior. These results introduce an adaptor/substrate pair for ClpXP and reveal broad diversity in adaptor-mediated proteolysis.

Publication types

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

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry*
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Caulobacter crescentus / genetics
  • Caulobacter crescentus / metabolism*
  • Cell Cycle
  • Crystallography, X-Ray
  • DNA Replication
  • Dimerization
  • Endopeptidase Clp / chemistry*
  • Endopeptidase Clp / genetics
  • Endopeptidase Clp / metabolism
  • Escherichia coli
  • Kinetics
  • Models, Molecular
  • Phosphoric Diester Hydrolases / chemistry*
  • Phosphoric Diester Hydrolases / genetics
  • Phosphoric Diester Hydrolases / metabolism
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Proteolysis
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction
  • Substrate Specificity


  • Adaptor Proteins, Signal Transducing
  • Bacterial Proteins
  • Recombinant Proteins
  • Phosphoric Diester Hydrolases
  • Endopeptidase Clp