BACKGROUND: The purine repressor (PurR) regulates genes that encode enzymes for purine biosynthesis. PurR has a two domain structure with an N-terminal DNA-binding domain (DBD) and a C-terminal corepressor-binding domain (CBD). The three dimensional structure of a ternary complex of PurR bound to both corepressor and a specific DNA sequence has recently been determined by X-ray crystallography. RESULTS: We have determined the solution structure of the PurR DBD by NMR. It contains three helices, with the first and second helices forming a helix-turn-helix motif. The tertiary structure of the three helices is very similar to that of the corresponding region in the ternary complex. The structure of the hinge helical region, however, which makes specific base contacts in the minor groove of DNA, is disordered in the DNA-free form. CONCLUSION: The stable formation of PurR hinge helices requires PurR dimerization, which brings the hinge regions proximal to each other. The dimerization of the hinge helices is likely to be controlled by the CBD dimerization interface, but is induced by specific-DNA binding.
PDB ID: 1PRUDownload
MMDB ID: 57168
PDB Deposition Date: 1995/5/8
Updated in MMDB: 2007/11
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Biological Unit for 1PRU: monomeric; determined by author
Molecular Components in 1PRU
Label Count Molecule
Protein (1 molecule)
Purine Repressor(Gene symbol: purR)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB