A novel DnaJ-like protein in Escherichia coli inserts into the cytoplasmic membrane with a type III topology

Mol Microbiol. 1996 Jun;20(6):1273-86. doi: 10.1111/j.1365-2958.1996.tb02646.x.


We describe a novel Escherichia coli protein, DjlA, containing a highly conserved J-region motif, which is present in the DnaJ protein chaperone family and required for interaction with DnaK. Remarkably, DjlA is shown to be a membrane protein, localized to the inner membrane with the unusual Type III topology (N-out, C-in). Thus, DjlA appears to present an extremely short N-terminus to the periplasm and has a single transmembrane domain (TMD) and a large cytoplasmic domain containing the C-terminal J-region. Analysis of the TMD of DjlA and recently identified homologues in Coxiella burnetti and Haemophilus influenzae revealed a striking pattern of conserved glycines (or rarely alanine), with a four-residue spacing. This motif, predicted to form a spiral groove in the TMD, is more marked than a repeating glycine motif, implicated in the dimerization of TMDs of some eukaryotic proteins. This feature of DjlA could represent a promiscuous docking mechanism for interaction with a variety of membrane proteins. DjlA null mutants can be isolated but these appear rapidly to accumulate suppressors to correct envelope and growth defects. Moderate (10-fold) overproduction of DjlA suppresses a mutation in FtsZ but markedly perturbs cell division and cell-envelope growth in minimal medium. We propose that DjlA plays a role in the correct assembly, activity and/or maintenance of a number of membrane proteins, including two-component signal-transduction systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Bacterial / immunology
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Cell Extracts
  • Cell Membrane / metabolism
  • Culture Media
  • Cytoskeletal Proteins*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins / chemistry
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Polysaccharides
  • Polysaccharides, Bacterial
  • Rabbits
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism


  • Antibodies, Bacterial
  • Bacterial Proteins
  • Cell Extracts
  • Culture Media
  • Cytoskeletal Proteins
  • DjlA protein, E coli
  • DnaJ protein, E coli
  • Escherichia coli Proteins
  • FtsZ protein, Bacteria
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Membrane Proteins
  • Polysaccharides
  • Polysaccharides, Bacterial
  • Recombinant Fusion Proteins
  • colanic acid