5D84

Staphyloferrin B precursor biosynthetic enzyme SbnA bound to PLP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.45 Å
  • R-Value Free: 0.175 
  • R-Value Work: 0.124 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Deciphering the Substrate Specificity of SbnA, the Enzyme Catalyzing the First Step in Staphyloferrin B Biosynthesis.

Kobylarz, M.J.Grigg, J.C.Liu, Y.Lee, M.S.Heinrichs, D.E.Murphy, M.E.

(2016) Biochemistry 55: 927-939

  • DOI: 10.1021/acs.biochem.5b01045
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Staphylococcus aureus assembles the siderophore, staphyloferrin B, from l-2,3-diaminopropionic acid (l-Dap), α-ketoglutarate, and citrate. Recently, SbnA and SbnB were shown to produce l-Dap and α-ketoglutarate from O-phospho-l-serine (OPS) and l-glu ...

    Staphylococcus aureus assembles the siderophore, staphyloferrin B, from l-2,3-diaminopropionic acid (l-Dap), α-ketoglutarate, and citrate. Recently, SbnA and SbnB were shown to produce l-Dap and α-ketoglutarate from O-phospho-l-serine (OPS) and l-glutamate. SbnA is a pyridoxal 5'-phosphate (PLP)-dependent enzyme with homology to O-acetyl-l-serine sulfhydrylases; however, SbnA utilizes OPS instead of O-acetyl-l-serine (OAS), and l-glutamate serves as a nitrogen donor instead of a sulfide. In this work, we examined how SbnA dictates substrate specificity for OPS and l-glutamate using a combination of X-ray crystallography, enzyme kinetics, and site-directed mutagenesis. Analysis of SbnA crystals incubated with OPS revealed the structure of the PLP-α-aminoacrylate intermediate. Formation of the intermediate induced closure of the active site pocket by narrowing the channel leading to the active site and forming a second substrate binding pocket that likely binds l-glutamate. Three active site residues were identified: Arg132, Tyr152, Ser185 that were essential for OPS recognition and turnover. The Y152F/S185G SbnA double mutant was completely inactive, and its crystal structure revealed that the mutations induced a closed form of the enzyme in the absence of the α-aminoacrylate intermediate. Lastly, l-cysteine was shown to be a competitive inhibitor of SbnA by forming a nonproductive external aldimine with the PLP cofactor. These results suggest a regulatory link between siderophore and l-cysteine biosynthesis, revealing a potential mechanism to reduce iron uptake under oxidative stress.


    Organizational Affiliation

    Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia , Vancouver, British Columbia, Canada V6T 1Z3.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Probable siderophore biosynthesis protein SbnA
A
326Staphylococcus aureus (strain Newman)Mutation(s): 0 
Gene Names: sbnA
EC: 2.5.1.140
Find proteins for A6QDA0 (Staphylococcus aureus (strain Newman))
Go to UniProtKB:  A6QDA0
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MG
Query on MG

Download SDF File 
Download CCD File 
A
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
PLP
Query on PLP

Download SDF File 
Download CCD File 
A
PYRIDOXAL-5'-PHOSPHATE
VITAMIN B6 Phosphate
C8 H10 N O6 P
NGVDGCNFYWLIFO-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.45 Å
  • R-Value Free: 0.175 
  • R-Value Work: 0.124 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 56.080α = 90.00
b = 115.828β = 90.00
c = 45.138γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data reduction
PDB_EXTRACTdata extraction
PHENIXphasing
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
Canadian Institutes of Health ResearchCanadaMOP-102596

Revision History 

  • Version 1.0: 2016-02-03
    Type: Initial release
  • Version 1.1: 2016-02-24
    Type: Database references