3zde

Potassium free structure of E. coli ExoIX

spinqualitylabelsall models 3zde, resolution 2.45Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3zde is a 1 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 3zd8, 3zd9, 3zda, 3zdb, 3zdc, 3zdd Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [XNI_ECO57] May have a role in processing of nucleic acids. It is probably not an exonuclease; metal-binding residues found in paralogs are missing (By similarity). Publication Abstract from PubMed Escherichia coli Exonuclease IX (ExoIX), encoded by the xni gene, was the first identified member of a novel subfamily of ubiquitous flap endonucleases (FENs), which possess only one of the two catalytic metal-binding sites characteristic of other FENs. We have solved the first structure of one of these enzymes, that of ExoIX itself, at high resolution in DNA-bound and DNA-free forms. In the enzyme-DNA cocrystal, the single catalytic site binds two magnesium ions. The structures also reveal a binding site in the C-terminal domain where a potassium ion is directly coordinated by five main chain carbonyl groups, and we show this site is essential for DNA binding. This site resembles structurally and functionally the potassium sites in the human FEN1 and exonuclease 1 enzymes. Fluorescence anisotropy measurements and the crystal structures of the ExoIX:DNA complexes show that this potassium ion interacts directly with a phosphate diester in the substrate DNA. The structure of Escherichia coli ExoIX--implications for DNA binding and catalysis in flap endonucleases.,Anstey-Gilbert CS, Hemsworth GR, Flemming CS, Hodskinson MR, Zhang J, Sedelnikova SE, Stillman TJ, Sayers JR, Artymiuk PJ Nucleic Acids Res. 2013 Jul 2. PMID:23821668 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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