3E43 : Q138F HincII bound to GTTAAC and cocrystallized with 2.5 mM MgCl2

  • Andrea C. Babić (Contributor)
  • Elizabeth J. Little (Contributor)
  • Veena M. Manohar (Contributor)
  • Nancy C Horton (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2008-08-26
Deposition Date:2008-08-08
Revision Date:2011-07-13
Molecular Weight:68241.77
Macromolecule Type:Protein#DNA
Residue Count:542
Atom Site Count:4432

Five new structures of the Q138F HincII enzyme bound to a total of three different DNA sequences and three different metal ions (Ca(2+), Mg(2+), and Mn(2+)) are presented. While previous structures were produced from soaking Ca(2+) into preformed Q138F HincII/DNA crystals, the new structures are derived from cocrystallization with Ca(2+), Mg(2+), or Mn(2+). The Mn(2)(+)-bound structure provides the first view of a product complex of Q138F HincII with cleaved DNA. Binding studies and a crystal structure show how Ca(2+) allows trapping of a Q138F HincII complex with noncognate DNA in a catalytically incompetent conformation. Many Q138F HincII/DNA structures show asymmetry, despite the binding of a symmetric substrate by a symmetric enzyme. The various complexes are fit into a model describing the different conformations of the DNA-bound enzyme and show how DNA conformational energetics determine DNA-cleavage rates by the Q138F HincII enzyme.
Date made available2008

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