2flc
Post-Reactive Complex of Restriction Endonuclease HinP1I with Nicked Cognate DNA and Magnesium Ions
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| , resolution 2.59Å | |||||||
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| Ligands: | , , , , , | ||||||
| Gene: | hinP1IR (Haemophilus influenzae) | ||||||
| Activity: | Type II site-specific deoxyribonuclease, with EC number 3.1.21.4 | ||||||
| Related: | 1YNM
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
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. 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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