1PL4: Crystal Structure Of Human Mnsod Y166f Mutant

The side chains of His30 and Tyr166 from adjacent subunits in the homotetramer human manganese superoxide dismutase (Mn-SOD) form a hydrogen bond across the dimer interface and participate in a hydrogen-bonded network that extends to the active site. Compared with wild-type Mn-SOD, the site-specific mutants H30N, Y166F, and the corresponding double mutant showed 10-fold decreases in steady-state constants for catalysis measured by pulse radiolysis. The observation of no additional effect upon the second mutation is an example of cooperatively interacting residues. A similar effect was observed in the thermal stability of these enzymes; the double mutant did not reduce the major unfolding transition to an extent greater than either single mutant. The crystal structures of these site-specific mutants each have unique conformational changes, but each has lost the hydrogen bond across the dimer interface, which results in a decrease in catalysis. These same mutations caused an enhancement of the dissociation of the product-inhibited complex. That is, His30 and Tyr166 in wild-type Mn-SOD act to prolong the lifetime of the inhibited complex. This would have a selective advantage in blocking a cellular overproduction of toxic H2O2.
PDB ID: 1PL4Download
MMDB ID: 25690
PDB Deposition Date: 2003/6/6
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.47  Å
Source Organism:
Similar Structures:
Biological Unit for 1PL4: tetrameric; determined by author and by software (PISA)
Molecular Components in 1PL4
Label Count Molecule
Proteins (4 molecules)
Superoxide Dismutase [mn], Mitochondrial(Gene symbol: SOD2)
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB