Functional analysis of CbpA, a DnaJ homolog and nucleoid-associated DNA-binding protein

J Biol Chem. 2006 Nov 10;281(45):34349-56. doi: 10.1074/jbc.M603365200. Epub 2006 Sep 14.


DnaK/Hsp70 proteins are universally conserved ATP-dependent molecular chaperones that help proteins adopt and maintain their native conformations. DnaJ/Hsp40 and GrpE are co-chaperones that assist DnaK. CbpA is an Escherichia coli DnaJ homolog. It acts as a multicopy suppressor for dnaJ mutations and functions in vitro in combination with DnaK and GrpE in protein remodeling reactions. CbpA binds nonspecifically to DNA with preference for curved DNA and is a nucleoid-associated protein. The DNA binding and co-chaperone activities of CbpA are modulated by CbpM, a small protein that binds specifically to CbpA. To identify the regions of CbpA involved in the interaction of CbpA with CbpM and those involved in DNA binding, we constructed and characterized deletion and substitution mutants of CbpA. We discovered that CbpA interacted with CbpM through its N-terminal J-domain. We found that the region C-terminal to the J-domain was required for DNA binding. Moreover, we found that the CbpM interaction, DNA binding, and co-chaperone activities were separable; some mutants were proficient in some functions and defective in others.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cross-Linking Reagents
  • DNA Helicases / genetics
  • DNA Helicases / metabolism
  • DNA, Bacterial / genetics
  • DNA, Bacterial / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • HSP40 Heat-Shock Proteins / genetics
  • HSP40 Heat-Shock Proteins / metabolism
  • HSP70 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / metabolism
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Luciferases / metabolism
  • Molecular Chaperones*
  • Mutagenesis, Site-Directed
  • Mutation / genetics
  • Plasmids / genetics
  • Protein Structure, Tertiary
  • Subcellular Fractions
  • Trans-Activators / genetics
  • Trans-Activators / metabolism


  • Bacterial Proteins
  • Carrier Proteins
  • CbpA protein, bacteria
  • CbpM protein, E coli
  • Cross-Linking Reagents
  • DNA, Bacterial
  • DNA-Binding Proteins
  • DnaJ protein, E coli
  • Escherichia coli Proteins
  • GrpE protein, E coli
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Trans-Activators
  • replication initiator protein
  • Luciferases
  • dnaK protein, E coli
  • DNA Helicases