4M55

Crystal structure of Human UDP-xylose synthase R236H substitution


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.86 Å
  • R-Value Free: 0.285 
  • R-Value Work: 0.228 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Man o' war mutation in UDP-alpha-D-xylose synthase favors the abortive catalytic cycle and uncovers a latent potential for hexamer formation.

Walsh Jr., R.M.Polizzi, S.J.Kadirvelraj, R.Howard, W.W.Wood, Z.A.

(2015) Biochemistry 54: 807-819

  • DOI: 10.1021/bi501357c
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The man o' war (mow) phenotype in zebrafish is characterized by severe craniofacial defects due to a missense mutation in UDP-α-d-xylose synthase (UXS), an essential enzyme in proteoglycan biosynthesis. The mow mutation is located in the UXS dimer in ...

    The man o' war (mow) phenotype in zebrafish is characterized by severe craniofacial defects due to a missense mutation in UDP-α-d-xylose synthase (UXS), an essential enzyme in proteoglycan biosynthesis. The mow mutation is located in the UXS dimer interface ∼16 Å away from the active site, suggesting an indirect effect on the enzyme mechanism. We have examined the structural and catalytic consequences of the mow mutation (R236H) in the soluble fragment of human UXS (hUXS), which shares 93% sequence identity with the zebrafish enzyme. In solution, hUXS dimers undergo a concentration-dependent association to form a tetramer. Sedimentation velocity studies show that the R236H substitution induces the formation of a new hexameric species. Using two new crystal structures of the hexamer, we show that R236H and R236A substitutions cause a local unfolding of the active site that allows for a rotation of the dimer interface necessary to form the hexamer. The disordered active sites in the R236H and R236A mutant constructs displace Y231, the essential acid/base catalyst in the UXS reaction mechanism. The loss of Y231 favors an abortive catalytic cycle in which the reaction intermediate, UDP-α-d-4-keto-xylose, is not reduced to the final product, UDP-α-d-xylose. Surprisingly, the mow-induced hexamer is almost identical to the hexamers formed by the deeply divergent UXS homologues from Staphylococcus aureus and Helicobacter pylori (21% and 16% sequence identity, respectively). The persistence of a latent hexamer-building interface in the human enzyme suggests that the ancestral UXS may have been a hexamer.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of Georgia , Athens, Georgia 30602, United States.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
UDP-glucuronic acid decarboxylase 1
A, B, C, D, E, F
336Homo sapiensMutation(s): 1 
Gene Names: UXS1
EC: 4.1.1.35
Find proteins for Q8NBZ7 (Homo sapiens)
Go to Gene View: UXS1
Go to UniProtKB:  Q8NBZ7
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
POP
Query on POP

Download SDF File 
Download CCD File 
A, C
PYROPHOSPHATE 2-
H2 O7 P2
XPPKVPWEQAFLFU-UHFFFAOYSA-L
 Ligand Interaction
SO4
Query on SO4

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Download CCD File 
A, B, C
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
NAD
Query on NAD

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Download CCD File 
A, B, C, D, E, F
NICOTINAMIDE-ADENINE-DINUCLEOTIDE
C21 H27 N7 O14 P2
BAWFJGJZGIEFAR-NNYOXOHSSA-N
 Ligand Interaction
UDP
Query on UDP

Download SDF File 
Download CCD File 
B, D
URIDINE-5'-DIPHOSPHATE
C9 H14 N2 O12 P2
XCCTYIAWTASOJW-XVFCMESISA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.86 Å
  • R-Value Free: 0.285 
  • R-Value Work: 0.228 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 83.171α = 90.00
b = 85.145β = 90.00
c = 292.549γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
PHENIXrefinement
PDB_EXTRACTdata extraction
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-08-28
    Type: Initial release
  • Version 1.1: 2014-11-12
    Type: Structure summary
  • Version 1.2: 2015-06-03
    Type: Database references
  • Version 1.3: 2018-04-25
    Type: Data collection, Database references