1xxc
From Proteopedia
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C-TERMINAL DOMAIN OF ESCHERICHIA COLI ARGININE REPRESSOR
Overview
The structure of the oligomerization and L-arginine binding domain of the, Escherichia coli arginine repressor (ArgR) has been determined using X-ray, diffraction methods at 2.2 A resolution with bound arginine and at 2.8 A, in the unliganded form. The oligomeric core is a 3-fold rotationally, symmetric hexamer formed from six identical subunits corresponding to the, 77 C-terminal residues (80 to 156) of ArgR. Each subunit has an alpha/beta, fold containing a four-stranded antiparallel beta-sheet and two, antiparallel alpha-helices. The hexamer is formed from two trimers, each, with tightly packed hydrophobic cores. In the absence of arginine, the, trimers stack back-to-back through a dyad-symmetric, sparsely packed, hydrophobic interface. Six molecules of arginine bind at the trimer-trimer, interface, each making ten hydrogen bonds to the protein including a, direct ion pair that crosslinks the two protein trimers. Solution, experiments with wild-type ArgR and oligomerization domain indicate that, the hexameric form is greatly stabilized upon arginine binding. The, crystal structures and solution experiments together suggest possible, mechanisms of how arginine activates ArgR to bind to its DNA targets and, provides a stereochemical basis for interpreting the results of, mutagenesis and biochemical experiments with ArgR.
About this Structure
1XXC is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure of the oligomerization and L-arginine binding domain of the arginine repressor of Escherichia coli., Van Duyne GD, Ghosh G, Maas WK, Sigler PB, J Mol Biol. 1996 Feb 23;256(2):377-91. PMID:8594204
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