PMID:8809778
| Citation |
Clarke, DJ, Jacq, A and Holland, IB (1996) A novel DnaJ-like protein in Escherichia coli inserts into the cytoplasmic membrane with a type III topology. Mol. Microbiol. 20:1273-86 |
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| Abstract |
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. |
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| Keywords |
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 |
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