1M0I

Crystal Structure of Bacteriophage T7 Endonuclease I with a Wild-Type Active Site


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.55 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.222 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Metal ions bound at the active site of the junction-resolving enzyme T7 endonuclease I

Hadden, J.M.Declais, A.C.Phillips, S.E.Lilley, D.M.

(2002) Embo J. 21: 3505-3515

  • DOI: 10.1093/emboj/cdf337
  • Primary Citation of Related Structures:  1M0D

  • PubMed Abstract: 
  • T7 endonuclease I is a nuclease that is selective for the structure of the four-way DNA junction. The active site is similar to those of a number of restriction enzymes. We have solved the crystal structure of endonuclease I with a wild-type active s ...

    T7 endonuclease I is a nuclease that is selective for the structure of the four-way DNA junction. The active site is similar to those of a number of restriction enzymes. We have solved the crystal structure of endonuclease I with a wild-type active site. Diffusion of manganese ions into the crystal revealed two peaks of electron density per active site, defining two metal ion-binding sites. Site 1 is fully occupied, and the manganese ion is coordinated by the carboxylate groups of Asp55 and Glu65, and the main chain carbonyl of Thr66. Site 2 is partially occupied, and the metal ion has a single protein ligand, the remaining carboxylate oxygen atom of Asp55. Isothermal titration calorimetry showed the sequential exothermic binding of two manganese ions in solution, with dissociation constants of 0.58 +/- 0.019 and 14 +/- 1.5 mM. These results are consistent with a two metal ion mechanism for the cleavage reaction, in which the hydrolytic water molecule is contained in the first coordination sphere of the site 1-bound metal ion.


    Organizational Affiliation

    Astbury Centre for Structural Molecular Biology, School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
endodeoxyribonuclease I
A, B, C, D
138Enterobacteria phage T7EC: 3.1.21.2
Find proteins for P00641 (Enterobacteria phage T7)
Go to UniProtKB:  P00641
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B, C
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.55 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.222 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 123.440α = 90.00
b = 134.550β = 90.00
c = 61.390γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
CCP4data scaling
CNSrefinement
SCALAdata scaling
MOSFLMdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2002-12-18
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance