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Updated: Aug 23, 2026

Inducing a Site Specific Replication Blockage in E. coli Using a Fluorescent Repressor Operator System
Published on: August 21, 2016
E. coli trp repressor forms a domain-swapped array in aqueous alcohol
Catherine L Lawson1, Brian Benoff, Tatyana Berger
1Rutgers University, Department of Chemistry and Chemical Biology, 610 Taylor Road, Piscataway, NJ 08854, USA. cathy.lawson@rutgers.edu
Abstract:
The E. coli trp repressor (trpR) homodimer recognizes its palindromic DNA binding site through a pair of flexible helix-turn-helix (HTH) motifs displayed on an intertwined helical core. Flexible N-terminal arms mediate association between dimers bound to tandem DNA sites. The 2.5 A X-ray structure of trpR crystallized in 30% (v/v) isopropanol reveals a substantial conformational rearrangement of HTH motifs and N-terminal arms, with the protein appearing in the unusual form of an ordered 3D domain-swapped supramolecular array. Small angle X-ray scattering measurements show that the self-association properties of trpR in solution are fundamentally altered by isopropanol.
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