PMID:7973627
| Citation |
Schumacher, MA, Choi, KY, Zalkin, H and Brennan, RG (1994) Crystal structure of LacI member, PurR, bound to DNA: minor groove binding by alpha helices. Science 266:763-70 |
|---|---|
| Abstract |
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. |
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| Keywords |
Amino Acid Sequence; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Sequence; Binding Sites; Computer Graphics; Crystallography, X-Ray; DNA/chemistry; DNA/metabolism; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli Proteins; Hydrogen Bonding; Hypoxanthine; Hypoxanthines/metabolism; Lac Repressors; Models, Molecular; Molecular Sequence Data; Nucleic Acid Conformation; Operator Regions, Genetic; Protein Conformation; Protein Structure, Secondary; Repressor Proteins/chemistry; Repressor Proteins/genetics; Repressor Proteins/metabolism |
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