A novel repeated DNA sequence located in the intergenic regions of bacterial chromosomes

Nucleic Acids Res. 1990 Nov 25;18(22):6503-8. doi: 10.1093/nar/18.22.6503.


We report the discovery of a novel group of highly conserved DNA sequences located within the intergenic regions of the chromosomes of Escherichia coli, Salmonella typhimurium and other bacteria. These intergenic repeat units (IRUs) are 124-127 nucleotides long and have the potential to form stable stem-loop structures. The location of these sequences within the intergenic regions is variable with respect to known or putative signals for transcription and translation of the flanking genes. Some of the IRU sequences are transcribed, others are probably not. The structure and possible functions of these sequences are discussed in relation to palindromic units and other repeated DNA sequences in bacteria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Biological Evolution
  • Chromosomes, Bacterial / ultrastructure*
  • Consensus Sequence
  • DNA / chemistry*
  • Escherichia coli / genetics*
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • RNA, Messenger / chemistry
  • Repetitive Sequences, Nucleic Acid
  • Salmonella typhimurium / genetics*
  • Thermodynamics


  • RNA, Messenger
  • DNA