1m08

Crystal structure of the unbound nuclease domain of ColE7

spinqualitylabelsall models 1m08, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1m08 is a 2 chain structure with sequence from Escherichia coli str. K-12 substr. W3110. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: PO4, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CEA7_ECOLX This plasmid-coded bactericidal protein is an endonuclease active on both single- and double-stranded DNA but with undefined specificity. Colicins are polypeptide toxins produced by and active against E.coli and closely related bacteria. 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 bacterial toxin ColE7 contains an H-N-H endonuclease domain (nuclease ColE7) that digests cellular DNA or RNA non-specifically in target cells, leading to cell death. In the host cell, protein Im7 forms a complex with ColE7 to inhibit its nuclease activity. Here, we present the crystal structure of the unbound nuclease ColE7 at a resolution of 2.1A. Structural comparison between the unbound and bound nuclease ColE7 in complex with Im7, suggests that Im7 is not an allosteric inhibitor that induces backbone conformational changes in nuclease ColE7, but rather one that inhibits by blocking the substrate-binding site. There were two nuclease ColE7 molecules in the P1 unit cell in crystals and they appeared as a dimer related to each other by a non-crystallographic dyad symmetry. Gel-filtration and cross-linking experiments confirmed that nuclease ColE7 indeed formed dimers in solution and that the dimeric conformation was more favored in the presence of double-stranded DNA. Structural comparison of nuclease ColE7 with the His-Cys box homing endonuclease I-PpoI further demonstrated that H-N-H motifs in dimeric nuclease ColE7 were oriented in a manner very similar to that of the betabetaalpha-fold of the active sites found in dimeric I-PpoI. A mechanism for the binding of double-stranded DNA by dimeric H-N-H nuclease ColE7 is suggested. The crystal structure of the nuclease domain of colicin E7 suggests a mechanism for binding to double-stranded DNA by the H-N-H endonucleases.,Cheng YS, Hsia KC, Doudeva LG, Chak KF, Yuan HS J Mol Biol. 2002 Nov 22;324(2):227-36. PMID:12441102 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Colicin 3D structures

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