Gal repressosome contains an antiparallel DNA loop

Mark Geanacopoulos, George Vasmatzis, Victor B. Zhurkin, Sankar Adhya

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Gal repressosome assembly and repression of the galoperon in Escherichia coil occurs when two dimeric GalR proteins and the histone-like HU protein bind to cognate sites causing DNA looping. Structure-based genetic analysis defined the GalR surfaces interacting to form a stacked, V-shaped, tetrameric structure. Stereochemical models of the four possible DNA loops compatible with the GalR tetramer configuration were constructed using the sequence-dependent structural parameters of the interoperator DNA and conformation changes caused by GalR and asymmetric HU binding. Evaluation of their DNA elastic energies gave unambiguous preference to a loop structure in which the two gal operators adopt an antiparallel orientation causing undertwisting of DNA.

Original languageEnglish (US)
Pages (from-to)432-436
Number of pages5
JournalNature Structural Biology
Issue number5
StatePublished - 2001

ASJC Scopus subject areas

  • Structural Biology
  • Biochemistry
  • Genetics


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