Database accession: MF7000837
Name: OHR (Pseudomonas aeruginosa)
PDB ID: 1n2f
Experimental method: X-ray (2.01 Å)
Assembly: Homodimer
Source organism: Pseudomonas aeruginosa
Primary publication of the structure:
Lesniak J, Barton WA, Nikolov DB
Structural and functional characterization of the Pseudomonas hydroperoxide resistance protein Ohr.
(2002) EMBO J. 21: 6649-59
PMID: 12485986
Abstract:
Bacteria have developed complex strategies to detoxify and repair damage caused by reactive oxygen species. These compounds, produced during bacterial aerobic respiration as well as by the host immune system cells as a defense mechanism against the pathogenic microorganisms, have the ability to damage nucleic acids, proteins and phospholipid membranes. Here we describe the crystal structure of Pseudomonas aeruginosa Ohr, a member of a recently discovered family of organic hydroperoxide resistance proteins. Ohr is a tightly folded homodimer, with a novel alpha/beta fold, and contains two active sites located at the monomer interface on opposite sides of the molecule. Using in vitro assays, we demonstrate that Ohr functions directly as a hydroperoxide reductase, converting both inorganic and organic hydroperoxides to less toxic metabolites. Site-directed mutagenesis confirms that the two conserved cysteines in each active site are essential for catalytic activity. We propose that the Ohr catalytic mechanism is similar to that of the structurally unrelated peroxiredoxins, directly utilizing highly reactive cysteine thiol groups to elicit hydroperoxide reduction.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown.Molecular function: not assigned
Biological process:
response to oxidative stress response to oxidative stress
Cellular component: not assigned
Structural annotations of the participating protein chains.Entry contents: 2 distinct polypeptide molecules
Chains: A, B
Notes: All chains according to the most probable oligomerization state stored in PDBe were considered.
Number of unique protein segments: 1
Name: Organic hydroperoxide resistance protein
Source organism: Pseudomonas aeruginosa
Length: 142 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMQTIKALYTATATATGGRDGRAVSSDGVLDVKLSTPRELGGQGGAATNPEQLFAAGYSACFIGALKFVAGQRKQTLPADASITGKVGIGQIPGGFGLEVELHINLPGLEREAAEALVAAAHQVCPYSNATRGNIDVRLNVSV
UniProtKB AC: Q9HZZ3 (positions: 1-142)
Coverage: 100%
Name: Organic hydroperoxide resistance protein
Source organism: Pseudomonas aeruginosa
Length: 142 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMQTIKALYTATATATGGRDGRAVSSDGVLDVKLSTPRELGGQGGAATNPEQLFAAGYSACFIGALKFVAGQRKQTLPADASITGKVGIGQIPGGFGLEVELHINLPGLEREAAEALVAAAHQVCPYSNATRGNIDVRLNVSV
UniProtKB AC: Q9HZZ3 (positions: 1-142)
Coverage: 100%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: OsmC-like protein
Evidence level: Direct evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
Ohr is a tightly folded homodimer with a large buried hydrophobic surface area. The two monomers are tightly wrapped around each other in a head-to-tail orientation. Dimerization is dominated by helix–helix packing interactions of two long helices at the center of the hydrophobic core of the dimeric enzyme. Also, each β-sheet is composed of six strands, three from one monomer and three from the other (beta sheet augmentation). The hydrophobic core, as well as the surrounding β-sheets, are generated by combining elements of both monomers, therefore, it is clear that the two polypeptide chains have to fold together to form active Ohr, and that each monomer would individually be unstable. The two active sites are also located at the dimer interface (PMID:12485986).
Chain A:
N/A
Chain B:
N/A
Surface and contacts features:
Structures from the PDB that contain the same number of proteins, and the proteins from the two structures show a sufficient degree of pairwise similarity, i.e. they belong to the same UniRef90 cluster (the full proteins exhibit at least 90% sequence identity) and convey roughly the same region to their respective interactions (the two regions from the two proteins share a minimum of 70% overlap). Download the CIF file (.cif)
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