BshA from Staphylococcus aureus complexed with UDP and N-acetylglucosamine

Experimental Data Snapshot

  • Resolution: 2.35 Å
  • R-Value Free: 0.196 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 

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A structural and functional analysis of the glycosyltransferase BshA from Staphylococcus aureus: Insights into the reaction mechanism and regulation of bacillithiol production.

Royer, C.J.Cook, P.D.

(2019) Protein Sci 28: 1083-1094

  • DOI: https://doi.org/10.1002/pro.3617
  • Primary Citation of Related Structures:  
    6D9T, 6N1X

  • PubMed Abstract: 

    Bacillithiol is a glucosamine-derived antioxidant found in several pathogenic Gram-positive bacteria. The compound is involved in maintaining the appropriate redox state within the cell as well as detoxifying foreign agents like the antibiotic fosfomycin. Bacillithiol is produced via the action of three enzymes, including BshA, a retaining GT-B glycosyltransferase that utilizes UDP-N-acetylglucosamine and l-malate to produce N-acetylglucosaminyl-malate. Recent studies suggest that retaining GT-B glycosyltransferases like BshA utilize a substrate-assisted mechanism that goes through an S N i-like transition state. In a previous study, we relied on X-ray crystallography as well as computational simulations to hypothesize the manner in which substrates would bind the enzyme, but several questions about substrate binding and the role of one of the amino acid residues persisted. Another study demonstrated that BshA might be subject to feedback inhibition by bacillithiol, but this phenomenon was not analyzed further to determine the exact mechanism of inhibition. Here we present X-ray crystallographic structures and steady-state kinetics results that help elucidate both of these issues. Our ligand-bound crystal structures demonstrate that the active site provides an appropriate steric and geometric arrangement of ligands to facilitate the substrate-assisted mechanism. Finally, we show that bacillithiol is competitive for UDP-N-acetylglucosamine with a K i value near 120-130 μM and likely binds within the BshA active site, suggesting that bacillithiol modulates BshA activity via feedback inhibition. The work presented here furthers our understanding of bacillithiol metabolism and can aid in the development of inhibitors to counteract resistance to antibiotics such as fosfomycin.

  • Organizational Affiliation

    Department of Chemistry, Grand Valley State University, Allendale, Michigan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glycosyltransferase377Staphylococcus aureus subsp. aureus CN1Mutation(s): 0 
Gene Names: SAKOR_01400
EC: 2.4.1
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on UDP

Download Ideal Coordinates CCD File 
C9 H14 N2 O12 P2
Query on NDG

Download Ideal Coordinates CCD File 
C [auth A]2-acetamido-2-deoxy-alpha-D-glucopyranose
C8 H15 N O6
Experimental Data & Validation

Experimental Data

  • Resolution: 2.35 Å
  • R-Value Free: 0.196 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 
  • Space Group: P 2 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 135.143α = 90
b = 135.143β = 90
c = 135.143γ = 90
Software Package:
Software NamePurpose
Aimlessdata scaling
PDB_EXTRACTdata extraction
HKL-2000data reduction

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)United States1R15GM117488

Revision History  (Full details and data files)

  • Version 1.0: 2019-08-21
    Type: Initial release
  • Version 1.1: 2020-01-01
    Changes: Author supporting evidence
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Structure summary
  • Version 2.1: 2023-10-11
    Changes: Data collection, Database references, Refinement description, Structure summary