2flc
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Post-Reactive Complex of Restriction Endonuclease HinP1I with Nicked Cognate DNA and Magnesium Ions
OverviewOverview
HinP1I recognizes and cleaves the palindromic tetranucleotide sequence G, downward arrowCGC in DNA. We report three structures of HinP1I-DNA, complexes: in the presence of Ca(2+) (pre-reactive complex), in the, absence of metal ion (binary complex) and in the presence of Mg(2+), (post-reactive complex). HinP1I forms a back-to-back dimer with two active, sites and two DNA duplexes bound on the outer surfaces of the dimer facing, away from each other. The 10 bp DNA duplexes undergo protein-induced, distortions exhibiting features of A-, B- and Z-conformations: bending on, one side (by intercalation of a phenylalanine side chain into the major, groove), base flipping on the other side of the recognition site (by, expanding the step rise distance of the local base pair to Z-form) and a, local A-form conformation between the two central C:G base pairs of the, recognition site (by binding of the N-terminal helix in the minor groove)., In the pre- and post-reactive complexes, two metals (Ca(2+) or Mg(2+)) are, found in the active site. The enzyme appears to cleave DNA sequentially, hydrolyzing first one DNA strand, as seen in the post-reactive complex in, the crystalline state, and then the other, as supported by the observation, that, in solution, a nicked DNA intermediate accumulates before, linearization.
About this StructureAbout this Structure
2FLC is a Single protein structure of sequence from Haemophilus influenzae with and as ligands. Active as Type II site-specific deoxyribonuclease, with EC number 3.1.21.4 Full crystallographic information is available from OCA.
ReferenceReference
DNA nicking by HinP1I endonuclease: bending, base flipping and minor groove expansion., Horton JR, Zhang X, Maunus R, Yang Z, Wilson GG, Roberts RJ, Cheng X, Nucleic Acids Res. 2006 Feb 9;34(3):939-48. Print 2006. PMID:16473850
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