1SO4

Crystal structure of K64A mutant of 3-keto-L-gulonate 6-phosphate decarboxylase with bound L-threonohydroxamate 4-phosphate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.162 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Evolution of Enzymatic Activities in the Orotidine 5'-Monophosphate Decarboxylase Suprafamily: Crystallographic Evidence for a Proton Relay System in the Active Site of 3-Keto-l-gulonate 6-Phosphate Decarboxylase(,)

Wise, E.L.Yew, W.S.Gerlt, J.A.Rayment, I.

(2004) Biochemistry 43: 6438-6446

  • DOI: 10.1021/bi0497392
  • Primary Citation of Related Structures:  1SO3, 1SO5, 1SO6

  • PubMed Abstract: 
  • 3-Keto-L-gulonate 6-phosphate decarboxylase (KGPDC), a member of the orotidine monophosphate decarboxylase (OMPDC) suprafamily, catalyzes the Mg(2+)-dependent decarboxylation of 3-keto-L-gulonate 6-phosphate to L-xylulose 5-phosphate. Structural and ...

    3-Keto-L-gulonate 6-phosphate decarboxylase (KGPDC), a member of the orotidine monophosphate decarboxylase (OMPDC) suprafamily, catalyzes the Mg(2+)-dependent decarboxylation of 3-keto-L-gulonate 6-phosphate to L-xylulose 5-phosphate. Structural and biochemical evidence suggests that the KGPDC reaction proceeds via a Mg(2+)-stabilized 1,2-cis-enediolate intermediate. Protonation of the enediolate intermediate occurs in a nonstereospecific manner to form L-xylulose 5-phosphate. Although the exact mechanism of proton delivery is not known, Glu112, His136, and Arg139 have been implicated in this process [Yew, W. S., Wise, E., Rayment, I., and Gerlt, J. A. (2004) Biochemistry 43, 6427-6437]. Surprisingly, single amino acid substitutions of these positions do not substantially reduce catalytic activity but rather alter the stereochemical course of the reaction. Here, we report the X-ray crystal structures of four mutants, K64A, H136A, E112Q, and E112Q/H136A, each determined in the presence of L-threonohydroxamate 4-phosphate, an analogue of the enediolate intermediate, to 1.7, 1.9, 1.8, and 1.9 A resolution, respectively. These structures reveal that substitutions of Lys64, Glu112, and His136 cause changes in the positions of the intermediate analogue and two active site water molecules that were previously identified as possible proton donors. These changes correlate with the observed alterations in the reaction stereochemistry for these mutants, thereby supporting a reaction mechanism in which water molecules competitively shuttle protons from the side chains of His136 and Arg139 to alternate faces of the cis-enediolate intermediate. These studies further underscore the wide variation in the reaction mechanisms in the OMPDC suprafamily.


    Organizational Affiliation

    Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
3-keto-L-gulonate 6-phosphate decarboxylase
A, B
216Escherichia coli (strain K12)Gene Names: ulaD (sgaH, yjfV)
EC: 4.1.1.85
Find proteins for P39304 (Escherichia coli (strain K12))
Go to UniProtKB:  P39304
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MG
Query on MG

Download SDF File 
Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
TX4
Query on TX4

Download SDF File 
Download CCD File 
A, B
L-THREONOHYDROXAMATE 4-PHOSPHATE
C4 H12 N O8 P
CSVKNYIFCYRDJM-NUNKFHFFSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.205 
  • R-Value Work: 0.162 
  • Space Group: C 1 2 1
Unit Cell:
Length (Å)Angle (°)
a = 122.976α = 90.00
b = 41.900β = 96.92
c = 91.322γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
HKL-2000data reduction
HKL-2000data collection
REFMACrefinement
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-06-08
    Type: Initial release
  • Version 1.1: 2008-04-29
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance