1AK0: P1 Nuclease In Complex With A Substrate Analog

Citation:
Abstract
The reaction mechanism of nuclease P1 from Penicillium citrinum has been investigated using single-stranded dithiophosphorylated di-, tetra-, and hexanucleotides as substrate analogs. The complexes crystallize in tetragonal and orthorhombic space groups and have been solved by molecular replacement. The high resolution structures give a clear picture of base recognition by P1 nuclease at its two nucleotide-binding sites, especially the 1.8 A structure of a P1-tetranucleotide complex which can be considered a P1-product complex. The observed binding modes are in agreement with a catalytic mechanism where the two closely spaced zinc ions activate the attacking water while the third, more exposed zinc ion stabilizes the leaving 03' oxyanion. Stacking as well as hydrogen bonding interactions with the base 5' to the cleaved phosphodiester bond are important elements of substrate binding and recognition. Modelling of a productive P1-substrate complex based on the solved structures suggests steric hindrance as the likely reason for the resistance of Rp-phosphorothioates and phosphorodithioates. Differences with the highly homologous nuclease S1 from Aspergillus oryzae are discussed.
PDB ID: 1AK0Download
MMDB ID: 47892
PDB Deposition Date: 1997/5/28
Updated in MMDB: 2012/10
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 1AK0: monomeric; determined by author
Molecular Components in 1AK0
Label Count Molecule
Protein (1 molecule)
1
P1 Nuclease
Molecule annotation
Chemicals (12 molecules)
1
4
2
4
3
1
4
3
* Click molecule labels to explore molecular sequence information.

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