2pub
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(New page: 200px<br /><applet load="2pub" size="450" color="white" frame="true" align="right" spinBox="true" caption="2pub, resolution 2.700Å" /> '''CRYSTAL STRUCTURE O...)
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Revision as of 11:33, 21 November 2007
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CRYSTAL STRUCTURE OF THE LACI FAMILY MEMBER, PURR, BOUND TO DNA: MINOR GROOVE BINDING BY ALPHA HELICES
Overview
The three-dimensional structure of a ternary complex of the purine, repressor, PurR, bound to both its corepressor, hypoxanthine, and the, 16-base pair purF operator site has been solved at 2.7 A resolution by, x-ray crystallography. The bipartite structure of PurR consists of an, amino-terminal DNA-binding domain and a larger carboxyl-terminal, corepressor binding and dimerization domain that is similar to that of the, bacterial periplasmic binding proteins. The DNA-binding domain contains a, helix-turn-helix motif that makes base-specific contacts in the major, groove of the DNA. Base contacts are also made by residues of, symmetry-related alpha helices, the "hinge" helices, which bind deeply in, the minor groove. Critical to hinge helix-minor groove binding is the, intercalation of the side chains of Leu54 and its symmetry-related mate, Leu54', into the central CpG-base pair step. These residues thereby act as, "leucine levers" to pry open the minor groove and kink the purF operator, by 45 degrees.
About this Structure
2PUB is a Single protein structure of sequence from Escherichia coli with ADE as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structure of LacI member, PurR, bound to DNA: minor groove binding by alpha helices., Schumacher MA, Choi KY, Zalkin H, Brennan RG, Science. 1994 Nov 4;266(5186):763-70. PMID:7973627
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