3GF4

Structure of UDP-galactopyranose mutase bound to UDP-glucose


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.45 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.192 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Ligand binding and substrate discrimination by UDP-galactopyranose mutase.

Gruber, T.D.Borrok, M.J.Westler, W.M.Forest, K.T.Kiessling, L.L.

(2009) J.Mol.Biol. 391: 327-340

  • DOI: 10.1016/j.jmb.2009.05.081

  • PubMed Abstract: 
  • Galactofuranose (Galf) residues are present in cell wall glycoconjugates of numerous pathogenic microbes. Uridine 5'-diphosphate (UDP) Galf, the biosynthetic precursor of Galf-containing glycoconjugates, is produced from UDP-galactopyranose (UDP-Galp ...

    Galactofuranose (Galf) residues are present in cell wall glycoconjugates of numerous pathogenic microbes. Uridine 5'-diphosphate (UDP) Galf, the biosynthetic precursor of Galf-containing glycoconjugates, is produced from UDP-galactopyranose (UDP-Galp) by the flavoenzyme UDP-galactopyranose mutase (UGM). The gene encoding UGM (glf) is essential for the viability of pathogens, including Mycobacterium tuberculosis, and this finding underscores the need to understand how UGM functions. Considerable effort has been devoted to elucidating the catalytic mechanism of UGM, but progress has been hindered by a lack of structural data for an enzyme-substrate complex. Such data could reveal not only substrate binding interactions but how UGM can act preferentially on two very different substrates, UDP-Galp and UDP-Galf, yet avoid other structurally related UDP sugars present in the cell. Herein, we describe the first structure of a UGM-ligand complex, which provides insight into the catalytic mechanism and molecular basis for substrate selectivity. The structure of UGM from Klebsiella pneumoniae bound to the substrate analog UDP-glucose (UDP-Glc) was solved by X-ray crystallographic methods and refined to 2.5 A resolution. The ligand is proximal to the cofactor, a finding that is consistent with a proposed mechanism in which the reduced flavin engages in covalent catalysis. Despite this proximity, the glucose ring of the substrate analog is positioned such that it disfavors covalent catalysis. This orientation is consistent with data indicating that UDP-Glc is not a substrate for UGM. The relative binding orientations of UDP-Galp and UDP-Glc were compared using saturation transfer difference NMR. The results indicate that the uridine moiety occupies a similar location in both ligand complexes, and this relevant binding mode is defined by our structural data. In contrast, the orientations of the glucose and galactose sugar moieties differ. To understand the consequences of these differences, we derived a model for the productive UGM-substrate complex that highlights interactions that can contribute to catalysis and substrate discrimination.


    Organizational Affiliation

    Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706-1544, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
UDP-galactopyranose mutase
A, B
390Klebsiella pneumoniaeGene Names: rfbD
EC: 5.4.99.9
Find proteins for Q48485 (Klebsiella pneumoniae)
Go to UniProtKB:  Q48485
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
UPG
Query on UPG

Download SDF File 
Download CCD File 
A
URIDINE-5'-DIPHOSPHATE-GLUCOSE
URIDINE-5'-MONOPHOSPHATE GLUCOPYRANOSYL-MONOPHOSPHATE ESTER
C15 H24 N2 O17 P2
HSCJRCZFDFQWRP-JZMIEXBBSA-N
 Ligand Interaction
FAD
Query on FAD

Download SDF File 
Download CCD File 
A, B
FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
 Ligand Interaction
U5P
Query on U5P

Download SDF File 
Download CCD File 
B
URIDINE-5'-MONOPHOSPHATE
C9 H13 N2 O9 P
DJJCXFVJDGTHFX-XVFCMESISA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
UPGKd: 750000 nM BINDINGMOAD
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.45 Å
  • R-Value Free: 0.238 
  • R-Value Work: 0.192 
  • Space Group: P 41
Unit Cell:
Length (Å)Angle (°)
a = 93.951α = 90.00
b = 93.951β = 90.00
c = 130.259γ = 90.00
Software Package:
Software NamePurpose
PHASERphasing
SCALEPACKdata scaling
DENZOdata reduction
REFMACrefinement
HKL-2000data reduction
PDB_EXTRACTdata extraction
HKL-2000data collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-06-09
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-11-01
    Type: Refinement description