DNA looping alters local DNA conformation during transcription

J Mol Biol. 1991 Jun 20;219(4):615-22. doi: 10.1016/0022-2836(91)90658-s.


The effect of protein-mediated DNA looping on local DNA conformation during active transcription was studied using the lac repressor-operator system. Our results suggest that lac repressor-mediated DNA looping within a plasmid DNA molecule containing two lac repressor binding sequences in vivo effectively separates plasmid DNA into two topological domains. Supercoils generated by transcription within each topological domain can be rapidly removed by DNA topoisomerase I.

Publication types

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

MeSH terms

  • Base Sequence
  • DNA, Bacterial / chemistry*
  • DNA, Bacterial / genetics
  • DNA, Superhelical / chemistry*
  • DNA, Superhelical / genetics
  • Escherichia coli / genetics*
  • Molecular Sequence Data
  • Nucleic Acid Conformation*
  • Plasmids
  • Protein Biosynthesis
  • Repressor Proteins / chemistry*
  • Repressor Proteins / metabolism
  • Transcription, Genetic*


  • DNA, Bacterial
  • DNA, Superhelical
  • Repressor Proteins