Database accession: MF7000475
Name: FosB with BS-Cys9 disulfide (Staphylococcus aureus)
PDB ID: 4nb0
Experimental method: X-ray (1.62 Å)
Assembly: Homodimer
Source organism: Staphylococcus aureus
Primary publication of the structure:
Thompson MK, Keithly ME, Goodman MC, Hammer ND, Cook PD, Jagessar KL, Harp J, Skaar EP, Armstrong RN
Structure and function of the genomically encoded fosfomycin resistance enzyme, FosB, from Staphylococcus aureus.
(2014) Biochemistry 53: 755-65
PMID: 24447055
Abstract:
The Gram-positive pathogen Staphylococcus aureus is a leading cause of global morbidity and mortality. Like many multi-drug-resistant organisms, S. aureus contains antibiotic-modifying enzymes that facilitate resistance to a multitude of antimicrobial compounds. FosB is a Mn(2+)-dependent fosfomycin-inactivating enzyme found in S. aureus that catalyzes nucleophilic addition of either l-cysteine (l-Cys) or bacillithiol (BSH) to the antibiotic, resulting in a modified compound with no bactericidal properties. The three-dimensional X-ray crystal structure of FosB from S. aureus (FosB(Sa)) has been determined to a resolution of 1.15 Å. Cocrystallization of FosB(Sa) with either l-Cys or BSH results in a disulfide bond between the exogenous thiol and the active site Cys9 of the enzyme. An analysis of the structures suggests that a highly conserved loop region of the FosB enzymes must change conformation to bind fosfomycin. While two crystals of FosB(Sa) contain Zn(2+) in the active site, kinetic analyses of FosB(Sa) indicated that the enzyme is inhibited by Zn(2+) for l-Cys transferase activity and only marginally active for BSH transferase activity. Fosfomycin-treated disk diffusion assays involving S. aureus Newman and the USA300 JE2 methicillin-resistant S. aureus demonstrate a marked increase in the sensitivity of the organism to the antibiotic in either the BSH or FosB null strains, indicating that both are required for survival of the organism in the presence of the antibiotic. This work identifies FosB as a primary fosfomycin-modifying pathway of S. aureus and establishes the enzyme as a potential therapeutic target for increased efficacy of fosfomycin against the pathogen.
Annotations from the GeneOntology database. Only terms that fit at least two of the interacting proteins are shown. Molecular function:
magnesium ion binding magnesium ion binding
transferase activity, transferring alkyl or aryl (other than methyl) groups transferase activity, transferring alkyl or aryl (other than methyl) groups
Biological process:
response to antibiotic response to antibiotic
Cellular component:
cytoplasm cytoplasm
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: Metallothiol transferase FosB
Source organism: Staphylococcus aureus
Length: 139 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMLKSINHICFSVRNLNDSIHFYRDILLGKLLLTGKKTAYFELAGLWIALNEEKDIPRNEIHFSYTHIAFTIDDSEFKYWHQRLKDNNVNILEGRVRDIRDRQSIYFTDPDGHKLELHTGTLENRLNYYKEAKPHMTFYK
UniProtKB AC: P60864 (positions: 2-138)
Coverage: 98%
Name: Metallothiol transferase FosB
Source organism: Staphylococcus aureus
Length: 139 residues
Sequence:Sequence according to the corresponding UniProt protein segmentMLKSINHICFSVRNLNDSIHFYRDILLGKLLLTGKKTAYFELAGLWIALNEEKDIPRNEIHFSYTHIAFTIDDSEFKYWHQRLKDNNVNILEGRVRDIRDRQSIYFTDPDGHKLELHTGTLENRLNYYKEAKPHMTFYK
UniProtKB AC: P60864 (positions: 2-138)
Coverage: 98%
Evidence demonstrating that the participating proteins are unstructured prior to the interaction and their folding is coupled to binding. Representative domain in related structures: Glyoxalase/Bleomycin resistance protein/Dioxygenase superfamily
Evidence level: Indirect evidence
Evidence coverage: The full structure participates in mutual synergistic folding.
Complex Evidence:
The VOC superfamily of metalloenzymes is characterized by a three-dimensional domain-swapped arrangement of tandem βαβββ-motifs (PMID:24447055). The original gene duplication event led to the βαβββ tandem structure, which appears to require dimerization for stability. Two different forms of domain-swapped dimers may coexist in solution (PMID:12121648) in which both subunits of the homodimer participate in coordination of each metal ion and formation of the U-shaped active sites in the enzyme (PMID:24004181). The complex is predominantly dimeric in solution (gel filtration) (PMID:12121648).
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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