Structural highlights
Function
[PURR_ECOLI] Is the main repressor of the genes involved in the de novo synthesis of purine nucleotides, regulating purB, purC, purEK, purF, purHD, purL, purMN and guaBA expression. In addition, it participates in the regulation or coregulation of genes involved in de novo pyrimidine nucleotide biosynthesis, salvage and uptake (pyrC, pyrD, carAB and codBA), and of several genes encoding enzymes necessary for nucleotide and polyamine biosynthesis (prsA, glyA, gcvTHP, speA, glnB). Binds to a 16-bp palindromic sequence located within the promoter region of pur regulon genes. The consensus binding sequence is 5'-ACGCAAACGTTTTCNT-3'. PurR is allosterically activated to bind its cognate DNA by binding the purine corepressors, hypoxanthine or guanine, thereby effecting transcription repression.[1] [2] [3] [4]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
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.
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[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Meng LM, Kilstrup M, Nygaard P. Autoregulation of PurR repressor synthesis and involvement of purR in the regulation of purB, purC, purL, purMN and guaBA expression in Escherichia coli. Eur J Biochem. 1990 Jan 26;187(2):373-9. PMID:2404765
- ↑ Rolfes RJ, Zalkin H. Purification of the Escherichia coli purine regulon repressor and identification of corepressors. J Bacteriol. 1990 Oct;172(10):5637-42. PMID:2211500
- ↑ Choi KY, Zalkin H. Structural characterization and corepressor binding of the Escherichia coli purine repressor. J Bacteriol. 1992 Oct;174(19):6207-14. PMID:1400170
- ↑ Devroede N, Thia-Toong TL, Gigot D, Maes D, Charlier D. Purine and pyrimidine-specific repression of the Escherichia coli carAB operon are functionally and structurally coupled. J Mol Biol. 2004 Feb 6;336(1):25-42. PMID:14741201
- ↑ Schumacher MA, Choi KY, Zalkin H, Brennan RG. Crystal structure of LacI member, PurR, bound to DNA: minor groove binding by alpha helices. Science. 1994 Nov 4;266(5186):763-70. PMID:7973627
