The Salmonella typhimurium invasion genes invF and invG encode homologues of the AraC and PulD family of proteins

Mol Microbiol. 1994 Aug;13(4):555-68. doi: 10.1111/j.1365-2958.1994.tb00450.x.


We have identified two novel Salmonella typhimurium genes, invF and invG, which are required for the efficient entry of these organisms into cultured epithelial cells. invF and invG are located immediately upstream of invE, a previously identified gene also required for Salmonella entry. Non-polar mutations in these genes rendered S. typhimurium severely deficient for entry into cultured epithelial cells. The nucleotide sequences of invF and invG indicated that these genes encode polypeptides with predicted molecular weights of 24,373 and 62,275, respectively. Proteins of similar sizes were observed when invF and invG were expressed in a bacteriophage T7 RNA polymerase-based expression system. Comparison of the predicted sequence of InvF with translated sequences in the existing databases indicated that this protein is homologous to members of the AraC family of prokaryotic transcription regulators. However, mutations in invF did not significantly affect the expression of other members of the inv locus. InvG was found to be homologous to members of the PulD family of specialized translocases. This homology suggests that InvG may be necessary for the export of invasion-related determinants or involved in the assembly of a supramolecular structure that promotes entry.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • AraC Transcription Factor
  • Bacterial Outer Membrane Proteins*
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Cells, Cultured
  • Cloning, Molecular
  • DNA-Binding Proteins*
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial / genetics*
  • Membrane Proteins / genetics
  • Membrane Transport Proteins*
  • Molecular Sequence Data
  • Mutagenesis
  • Recombinant Proteins / biosynthesis
  • Repressor Proteins / genetics
  • Restriction Mapping
  • Salmonella typhimurium / genetics*
  • Salmonella typhimurium / pathogenicity
  • Sequence Homology, Amino Acid
  • Transcription Factors*
  • Transcription, Genetic
  • Virulence / genetics


  • AraC Transcription Factor
  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • DNA-Binding Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Recombinant Proteins
  • Repressor Proteins
  • Transcription Factors
  • invF protein, Salmonella
  • invG protein, Salmonella typhimurium
  • PulD protein, Klebsiella pneumoniae

Associated data

  • GENBANK/U08280