Structural basis for ligand-regulated oligomerization of AraC.
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Soisson SM, MacDougall-Shackleton B, Schleif R, Wolberger C
Structural basis for ligand-regulated oligomerization of AraC.
Science. 1997 Apr 18;276(5311):421-5.
- PubMed ID
- 9103202 [ View in PubMed]
- Abstract
The crystal structure of the arabinose-binding and dimerization domain of the Escherchia 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 beta 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 sugar-binding pocket and allowing it 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.