Crystal structure of the disulfide reductase MerA from Staphylococcus aureus

Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.209 
  • R-Value Observed: 0.211 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.2 of the entry. See complete history


MerA functions as a hypothiocyanous acid reductase and defense mechanism in Staphylococcus aureus.

Shearer, H.L.Loi, V.V.Weiland, P.Bange, G.Altegoer, F.Hampton, M.B.Antelmann, H.Dickerhof, N.

(2023) Mol Microbiol 119: 456-470

  • DOI: https://doi.org/10.1111/mmi.15035
  • Primary Citation of Related Structures:  
    8AJJ, 8AJK

  • PubMed Abstract: 

    The major pathogen Staphylococcus aureus has to cope with host-derived oxidative stress to cause infections in humans. Here, we report that S. aureus tolerates high concentrations of hypothiocyanous acid (HOSCN), a key antimicrobial oxidant produced in the respiratory tract. We discovered that the flavoprotein disulfide reductase (FDR) MerA protects S. aureus from this oxidant by functioning as a HOSCN reductase, with its deletion sensitizing bacteria to HOSCN. Crystal structures of homodimeric MerA (2.4 Å) with a Cys 43 -Cys 48 intramolecular disulfide, and reduced MerACys 43 S (1.6 Å) showed the FAD cofactor close to the active site, supporting that MerA functions as a group I FDR. MerA is controlled by the redox-sensitive repressor HypR, which we show to be oxidized to intermolecular disulfides under HOSCN stress, resulting in its inactivation and derepression of merA transcription to promote HOSCN tolerance. Our study highlights the HOSCN tolerance of S. aureus and characterizes the structure and function of MerA as a major HOSCN defense mechanism. Crippling the capacity to respond to HOSCN may be a novel strategy for treating S. aureus infections.

  • Organizational Affiliation

    Centre for Free Radical Research, Department of Pathology and Biomedical Science, University of Otago Christchurch, Christchurch, New Zealand.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Dihydrolipoamide dehydrogenaseA [auth C],
B [auth A],
C [auth B],
446Staphylococcus aureusMutation(s): 0 
Gene Names: 
EC: (PDB Primary Data), 1 (PDB Primary Data)
Find proteins for Q2G0I4 (Staphylococcus aureus (strain NCTC 8325 / PS 47))
Explore Q2G0I4 
Go to UniProtKB:  Q2G0I4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ2G0I4
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.209 
  • R-Value Observed: 0.211 
  • Space Group: P 63 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 250.63α = 90
b = 250.63β = 90
c = 141.14γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
XSCALEdata scaling

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Not funded--

Revision History  (Full details and data files)

  • Version 1.0: 2023-03-01
    Type: Initial release
  • Version 1.1: 2023-04-26
    Changes: Database references
  • Version 1.2: 2024-02-07
    Changes: Data collection, Refinement description