Structural basis for ligand-regulated oligomerization of AraC

Stephen M. Soisson, Beth MacDougall-Shackleton, Robert Schleif, Cynthia Wolberger

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Abstract

The crystal structure of the arabinose-binding and dimerization domain of the Escherichia coli gene regulatory protein AraC was determined in the presence and absence of L-arabinose. The 1.5 angstrom structure of the arabinose-bound molecule shows that the protein adopts an unusual fold, binding sugar within a β barrel and completely burying the arabinose with the amino-terminal arm of the protein. Dimer contacts in the presence of arabinose are mediated by an antiparallel coiled-coil. In the 2.8 angstrom structure of the uncomplexed protein, the amino-terminal arm is disordered, uncovering the sugarbinding pocket and allowing if to serve as an oligomerization interface. The ligand-gated oligomerization as seen in AraC provides the basis of a plausible mechanism for modulating the protein's DNA- looping properties.

Original languageEnglish (US)
Pages (from-to)421-425
Number of pages5
JournalScience
Volume276
Issue number5311
DOIs
Publication statusPublished - Apr 18 1997

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ASJC Scopus subject areas

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Cite this

Soisson, S. M., MacDougall-Shackleton, B., Schleif, R., & Wolberger, C. (1997). Structural basis for ligand-regulated oligomerization of AraC. Science, 276(5311), 421-425. https://doi.org/10.1126/science.276.5311.421