PDBsum entry 1pl4

Oxidoreductase

PDB id: 1pl4

Contents

Protein chains

198 a.a. *

Metals

_MN ×4

Waters ×680

* Residue conservation analysis

PDB id:

1pl4

Name:

Oxidoreductase

Title:

Crystal structure of human mnsod y166f mutant

Structure:

Superoxide dismutase [mn], mitochondrial. Chain: a, b, c, d. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Organelle: mitochondria. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Tetramer (from PQS)

Resolution:

1.47Å R-factor: 0.201 R-free: 0.237

Authors:

L.Fan,J.A.Tainer

Key ref:

A.S.Hearn et al. (2004). Amino acid substitution at the dimeric interface of human manganese superoxide dismutase. J Biol Chem, 279, 5861-5866. PubMed id: 14638684 DOI: 10.1074/jbc.M311310200

Date:

06-Jun-03 Release date: 16-Dec-03

Protein chains

P04179  (SODM_HUMAN) -  Superoxide dismutase [Mn], mitochondrial from Homo sapiens

Seq: 222 a.a.

Struc: 198 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.15.1.1 - superoxide dismutase.
• Reaction: 2 superoxide + 2 H⁺ = H2O2 + O2
• Cofactor: Fe cation or Mn(2+) or (Zn(2+) and Cu cation)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1074/jbc.M311310200

J Biol Chem 279:5861-5866 (2004)

PubMed id: 14638684

Amino acid substitution at the dimeric interface of human manganese superoxide dismutase.

A.S.Hearn, L.Fan, J.R.Lepock, J.P.Luba, W.B.Greenleaf, D.E.Cabelli, J.A.Tainer, H.S.Nick, D.N.Silverman.

ABSTRACT

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.

Selected figure(s)

Figure 2.
FIG. 2. The least squares superimposed structures of wild-type human Mn-SOD (purple) and Y166F Mn-SOD (green) showing residues in the active site. In the mutant, the side chain of Asn171(B) emanating from the adjacent residue has rotated 130° around the C- -C- bond to form a hydrogen bond with His30. The side chain of His30 has also rotated 98° around the C- -C- bond overlapping the site of a water molecule in the wild type.

Figure 3.
FIG. 3. The least squares superimposed structures of wild-type human Mn-SOD (purple) and H30N/Y166F Mn-SOD (yellow) showing residues in the active site. Similar to Asn171(B) in the single mutant, this side chain turned toward subunit A in the double mutant, but there is no hydrogen bond between Asn171(B) and Asn30(A). Instead, the N -2 of Asn30 formed a weak hydrogen bond with the phenolic OH of Tyr34.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 5861-5866) copyright 2004.

Figures were selected by an automated process.