Improved allelic exchange vectors and their use to analyze 987P fimbria gene expression

Gene. 1998 Jan 30;207(2):149-57. doi: 10.1016/s0378-1119(97)00619-7.


A series of vectors has been developed to provide improved positive and negative selection for allelic exchange. Based on homologous regions of DNA ranging in size from less than 200 bp to over 1 kb, we have successfully used these new plasmids to introduce or remove markers in chromosomal or plasmid DNA. Wild type fimbria genes were replaced both in Salmonella enteritidis (sefA, agfA and fimC) and Escherichia coli (fasA and fasH). Regulation of 987P fimbriation could be identified after replacement of fasA and fasH with allelic reporter fusions. The expression of fasA but not fasH is dependent upon the osmolarity of the growth medium in an HNS-dependent manner, but unlike some other fimbrial systems expression is not dependent on the exogenous iron concentration.

Publication types

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

MeSH terms

  • Adhesins, Escherichia coli / genetics*
  • Alleles
  • Antigens, Bacterial / genetics*
  • Antigens, Surface / genetics*
  • Bacterial Proteins / genetics
  • Base Sequence
  • Chloramphenicol O-Acetyltransferase / genetics
  • DNA, Bacterial
  • DNA-Binding Proteins / genetics
  • Escherichia coli / genetics*
  • Fimbriae Proteins*
  • Fimbriae, Bacterial / genetics*
  • Gene Expression Regulation, Bacterial*
  • Genetic Vectors*
  • Iron / physiology
  • Molecular Sequence Data
  • Osmolar Concentration
  • Recombinant Fusion Proteins / genetics
  • Salmonella enteritidis / genetics*
  • beta-Lactamases / genetics


  • Adhesins, Escherichia coli
  • Antigens, Bacterial
  • Antigens, Surface
  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Binding Proteins
  • H-NS protein, bacteria
  • Recombinant Fusion Proteins
  • antigen 987P, E coli
  • Fimbriae Proteins
  • Iron
  • Chloramphenicol O-Acetyltransferase
  • beta-Lactamases