Imp/OstA is required for cell envelope biogenesis in Escherichia coli

Mol Microbiol. 2002 Sep;45(5):1289-302. doi: 10.1046/j.1365-2958.2002.03091.x.


In Gram-negative bacteria, all components of the outer membrane are synthesized in the cytoplasm or the cytoplasmic leaflet of the inner membrane and must thus traverse the inner membrane and the periplasm on the way to their final destination. In this study, we show Imp/OstA to have characteristics typical for proteins involved in envelope biogenesis. Imp is essential and forms a high-molecular-weight disulphide-bonded complex in the outer membrane. Upon depletion of Imp, lipids and outer membrane proteins appear in a novel membrane fraction with higher density than the outer membrane. We propose Imp to be part of a targeting/usher system for components of the outer membrane.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Base Sequence
  • Cell Membrane / metabolism*
  • DNA, Bacterial / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Genes, Bacterial
  • Macromolecular Substances
  • Membrane Lipids / metabolism
  • Molecular Weight
  • Mutation


  • Bacterial Outer Membrane Proteins
  • DNA, Bacterial
  • Escherichia coli Proteins
  • Macromolecular Substances
  • Membrane Lipids