1e7d
|
ENDONUCLEASE VII (ENDOVII) FROM PHAGE T4
OverviewOverview
The structure of the N62D mutant of the junction-resolving endonuclease, VII (EndoVII) from phage T4 has been refined at 1.3 A, and a second, wild-type crystal form solved and refined at 2.8 A resolution. Comparison, of the mutant with the wild-type protein structure in two different, crystal environments reveals considerable conformational flexibility at, the dimer level affecting the substrate-binding cleft, the dimerization, interface and the orientation of the C-terminal domains. The opening of, the DNA-binding cleft, the orientation of the C-terminal domains relative, to the central dimerization domain as well as the relative positioning of, helices in the dimerization interface appear to be sensitive to the, crystal packing environment. The highly unexpected rearrangement within, the extended hydrophobic interface does change the contact surface area, but keeps the number of hydrophobic contacts about the same and will, therefore not require significant energy input. The conformational, flexibility most likely is of functional significance for the broad, substrate specificity of EndoVII. Binding of sulphate ions in the mutant, structure and their positions relative to the active-site metal ions and, residues known to be essential for catalysis allows us to propose a, possible catalytic mechanism. A comparison with the active-site geometries, of other magnesium-dependent nucleases, among them the homing endonuclease, I-PpoI and Serratia endonuclease, shows common features, suggesting, related catalytic mechanisms.
About this StructureAbout this Structure
1E7D is a Single protein structure of sequence from Enterobacteria phage t2 with ZN, CA and CL as ligands. Structure known Active Sites: AC1, AC2, AC3 and AC4. Full crystallographic information is available from OCA.
ReferenceReference
Conformational flexibility in T4 endonuclease VII revealed by crystallography: implications for substrate binding and cleavage., Raaijmakers H, Toro I, Birkenbihl R, Kemper B, Suck D, J Mol Biol. 2001 Apr 27;308(2):311-23. PMID:11327769
Page seeded by OCA on Mon Nov 5 16:07:25 2007