Chaperone function of FkpA, a heat shock prolyl isomerase, in the periplasm of Escherichia coli

Mol Microbiol. 2001 Jan;39(1):199-210. doi: 10.1046/j.1365-2958.2001.02250.x.


The nature of molecular chaperones in the periplasm of Escherichia coli that assist newly translocated proteins to reach their native state has remained poorly defined. Here, we show that FkpA, a heat shock periplasmic peptidyl-prolyl cis/trans isomerase (PPIase), suppresses the formation of inclusion bodies from a defective-folding variant of the maltose-binding protein, MalE31. This chaperone-like activity of FkpA, which is independent of its PPIase activity, requires a full-length structure of the protein. In vitro, FkpA does not catalyse a slow rate-limiting step in the refolding of MalE31, but prevents its aggregation at stoichiometric amounts and promotes the reactivation of denaturated citrate synthase. We propose that FkpA functions as a chaperone for envelope proteins in the bacterial periplasm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters*
  • Binding Sites / genetics
  • Carrier Proteins / metabolism
  • Circular Dichroism
  • Citrate (si)-Synthase / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins*
  • Heat-Shock Proteins / metabolism*
  • Heat-Shock Response
  • Immunophilins / genetics
  • Immunophilins / metabolism*
  • Inclusion Bodies
  • Maltose-Binding Proteins
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Monosaccharide Transport Proteins*
  • Peptidylprolyl Isomerase / metabolism*
  • Periplasm / metabolism*
  • Periplasmic Binding Proteins*
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Transport
  • Sequence Deletion


  • ATP-Binding Cassette Transporters
  • Carrier Proteins
  • Escherichia coli Proteins
  • Heat-Shock Proteins
  • MalE protein, E coli
  • Maltose-Binding Proteins
  • Membrane Proteins
  • Monosaccharide Transport Proteins
  • Periplasmic Binding Proteins
  • maltose transport system, E coli
  • Citrate (si)-Synthase
  • Immunophilins
  • Peptidylprolyl Isomerase
  • FkpA protein, E coli