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| {{STRUCTURE_1xhu| PDB=1xhu | SCENE= }} | | {{STRUCTURE_1xhu| PDB=1xhu | SCENE= }} |
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| '''HincII bound to cleaved, cognate DNA containing GTCGAC'''
| | ===HincII bound to cleaved, cognate DNA containing GTCGAC=== |
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| ==Overview==
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| The three-dimensional X-ray crystal structures of HincII bound to cognate DNA containing GTCGAC and Mn(2+) or Mg(2+), at 2.50A and 2.95A resolution, respectively, are presented. In both structures, the DNA is found cleaved, and the positions of the active-site groups, cleaved phosphate group, and 3' oxygen atom of the leaving group are in very similar positions. Two highly occupied Mn(2+) positions are found in each active site of the four crystallographically independent subunit copies in the HincII/DNA/Mn(2+) structure. The manganese ion closest to the previously identified single Ca(2+) position of HincII is shifted 1.7A and has lost direct ligation to the active-site aspartate residue, Asp127. A Mn(2+)-ligated water molecule in a position analogous to that seen in the HincII/DNA/Ca(2+) structure, and proposed to be the attacking nucleophile, is beyond hydrogen bonding distance from the active-site lysine residue, Lys129, but remains within hydrogen bonding distance from the proRp oxygen atom of the phosphate group 3' to the scissile phosphate group. In addition, the position of the cleaved phosphate group is on the opposite side of the axis connecting the two metal ions relative to that found in the BamHI/product DNA/Mn(2+) structure. Mechanistic implications are discussed, and a model for the two-metal-ion mechanism of DNA cleavage by HincII is proposed. | | The line below this paragraph, {{ABSTRACT_PUBMED_15476804}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15476804 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15476804}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Phosphoryl transfer]] | | [[Category: Phosphoryl transfer]] |
| [[Category: Restriction endonuclease]] | | [[Category: Restriction endonuclease]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:02:59 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 14:04:20 2008'' |
