1SZG

A198G:L230A flavocytochrome b2 with sulfite bound


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.225 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Altered Substrate Specificity in Flavocytochrome b(2): Structural Insights into the Mechanism of l-Lactate Dehydrogenation

Mowat, C.G.Wehenkel, A.Green, A.J.Walkinshaw, M.D.Reid, G.A.Chapman, S.K.

(2004) Biochemistry 43: 9519-9526

  • DOI: 10.1021/bi049263m
  • Primary Citation of Related Structures:  
    1SZG, 1SZF, 1SZE

  • PubMed Abstract: 
  • Flavocytochrome b(2) from Saccharomyces cerevisiae is a l-lactate/cytochrome c oxidoreductase belonging to a large family of 2-hydroxyacid-dependent flavoenzymes. The crystal structure of the enzyme, with pyruvate bound at the active site, has been determined [Xia, Z ...

    Flavocytochrome b(2) from Saccharomyces cerevisiae is a l-lactate/cytochrome c oxidoreductase belonging to a large family of 2-hydroxyacid-dependent flavoenzymes. The crystal structure of the enzyme, with pyruvate bound at the active site, has been determined [Xia, Z.-X., and Mathews, F. S. (1990) J. Mol. Biol. 212, 837-863]. The authors indicate that the methyl group of pyruvate is in close contact with Ala198 and Leu230. These two residues are not well-conserved throughout the family of (S)-2-hydroxy acid oxidases/dehydrogenases. Thus, to probe substrate specificity in flavocytochrome b(2), these residues have been substituted by glycine and alanine, respectively. Kinetic studies on the L230A mutant enzyme and the A198G/L230A double mutant enzyme indicate a change in substrate selectivity for the enzyme toward larger (S)-2-hydroxy acids. In particular, the L230A enzyme is more efficient at utilizing (S)-2-hydroxyoctanoate by a factor of 40 as compared to the wild-type enzyme [Daff, S., Manson, F. D. C., Reid, G. A., and Chapman, S. K. (1994) Biochem. J. 301, 829-834], and the A198G/L230A double mutant enzyme is 6-fold more efficient with the aromatic substrate l-mandelate than it is with l-lactate [Sinclair, R., Reid, G. A., and Chapman, S. K. (1998) Biochem. J. 333, 117-120]. To complement these solution studies, we have solved the structure of the A198G/L230A enzyme in complex with pyruvate and as the FMN-sulfite adduct (both to 2.7 A resolution). We have also obtained the structure of the L230A mutant enzyme in complex with phenylglyoxylate (the product of mandelate oxidation) to 3.0 A resolution. These structures reveal the increased active-site volume available for binding larger substrates, while also confirming that the integrity of the interactions important for catalysis is maintained. In addition to this, the mode of binding of the bulky phenylglyoxylate at the active site is in accordance with the operation of a hydride transfer mechanism for substrate oxidation/flavin reduction in flavocytochrome b(2), whereas a mechanism involving the formation of a carbanion intermediate would appear to be sterically prohibited.


    Organizational Affiliation

    School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Cytochrome b2, mitochondrial AB511Saccharomyces cerevisiaeMutation(s): 2 
Gene Names: CYB2
EC: 1.1.2.3
Find proteins for P00175 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Explore P00175 
Go to UniProtKB:  P00175
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FNS
Query on FNS

Download Ideal Coordinates CCD File 
A, B
N-SULFO-FLAVIN MONONUCLEOTIDE
C17 H21 N4 O12 P S
ZLPUGFBBLGQWBS-SCRDCRAPSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.225 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 163.966α = 90
b = 163.966β = 90
c = 112.508γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
REFMACrefinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-07-27
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance