3N7B : SgrAI bound to secondary site DNA and Ca(II)

  • Elizabeth J. Little (Contributor)
  • Pete W. Dunten (Contributor)
  • Nancy C Horton (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2010-11-24
Deposition Date:2010-05-26
Revision Date:2011-07-13
Molecular Weight:85803.39
Macromolecule Type:Protein#DNA
Residue Count:708
Atom Site Count:6575

SgrAI is a type II restriction endonuclease that cuts an unusually long recognition sequence and exhibits allosteric self-activation with expansion of DNA-sequence specificity. The three-dimensional crystal structures of SgrAI bound to cleaved primary-site DNA and Mg²(+) and bound to secondary-site DNA with either Mg²(+) or Ca²(+) are presented. All three structures show a conformation of enzyme and DNA similar to the previously determined dimeric structure of SgrAI bound to uncleaved primary-site DNA and Ca²(+) [Dunten et al. (2008), Nucleic Acids Res. 36, 5405-5416], with the exception of the cleaved bond and a slight shifting of the DNA in the SgrAI/cleaved primary-site DNA/Mg²(+) structure. In addition, a new metal ion binding site is located in one of the two active sites in this structure, which is consistent with proposals for the existence of a metal-ion site near the 3'-O leaving group.
Date made available2010

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