Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Dihedral - D2  (3D View)
Global Stoichiometry: Homo 4-mer - A4 

Biological assembly 1 assigned by authors and generated by PISA,PQS (software)

Macromolecule Content

• Total Structure Weight: 124.76 kDa 
• Atom Count: 8858 
• Residue Count: 1087 
• Unique protein chains: 1

1OZF

The crystal structure of Klebsiella pneumoniae acetolactate synthase with enzyme-bound cofactors

• DOI: 10.2210/pdb1OZF/pdb

• Classification: LYASE
• Organism(s): Klebsiella pneumoniae
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2003-04-09 Released: 2003-11-11 
• Deposition Author(s): Pang, S.S., Duggleby, R.G., Schowen, R.L., Guddat, L.W.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.30 Å
• R-Value Free: 0.214 
• R-Value Work: 0.165 
• R-Value Observed: 0.165 

Literature

The Crystal Structures of Klebsiella pneumoniae Acetolactate Synthase with Enzyme-bound Cofactor and with an Unusual Intermediate.

Pang, S.S., Duggleby, R.G., Schowen, R.L., Guddat, L.W.

(2004) J Biol Chem 279: 2242-2253

• PubMed: 14557277 
• DOI: 10.1074/jbc.M304038200
• Primary Citation of Related Structures:  
  1N0H, 1OZH, 1OZG, 1OZF


• PubMed Abstract: 
  

Acetohydroxyacid synthase (AHAS) and acetolactate synthase (ALS) are thiamine diphosphate (ThDP)-dependent enzymes that catalyze the decarboxylation of pyruvate to give a cofactor-bound hydroxyethyl group, which is transferred to a second molecule of pyruvate to give 2-acetolactate. AHAS is found in plants, fungi, and bacteria, is involved in the biosynthesis of the branched-chain amino acids, and contains non-catalytic FAD. ALS is found only in some bacteria, is a catabolic enzyme required for the butanediol fermentation, and does not contain FAD. Here we report the 2.3-A crystal structure of Klebsiella pneumoniae ALS. The overall structure is similar to AHAS except for a groove that accommodates FAD in AHAS, which is filled with amino acid side chains in ALS. The ThDP cofactor has an unusual conformation that is unprecedented among the 26 known three-dimensional structures of nine ThDP-dependent enzymes, including AHAS. This conformation suggests a novel mechanism for ALS. A second structure, at 2.0 A, is described in which the enzyme is trapped halfway through the catalytic cycle so that it contains the hydroxyethyl intermediate bound to ThDP. The cofactor has a tricyclic structure that has not been observed previously in any ThDP-dependent enzyme, although similar structures are well known for free thiamine. This structure is consistent with our proposed mechanism and probably results from an intramolecular proton transfer within a tricyclic carbanion that is the true reaction intermediate. Modeling of the second molecule of pyruvate into the active site of the enzyme with the bound intermediate is consistent with the stereochemistry and specificity of ALS.

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Organizational Affiliation: 

Department of Biochemistry and Molecular Biology, the University of Queensland, Brisbane, Queensland 4072, Australia.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Acetolactate synthase, catabolic	A, B	566	Klebsiella pneumoniae	Mutation(s): 0  Gene Names: BUDB OR ILVK, budB, ilvK EC: 4.1.3.18 (PDB Primary Data), 2.2.1.6 (UniProt)
Find proteins for P27696 (Klebsiella pneumoniae) Explore P27696  Go to UniProtKB:  P27696

Small Molecules

Ligands 4 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
TPP	A, B	THIAMINE DIPHOSPHATE C12 H19 N4 O7 P2 S AYEKOFBPNLCAJY-UHFFFAOYSA-O
PEG	A, B	DI(HYDROXYETHYL)ETHER C4 H10 O3 MTHSVFCYNBDYFN-UHFFFAOYSA-N
PO4	A, B	PHOSPHATE ION O4 P NBIIXXVUZAFLBC-UHFFFAOYSA-K
MG	A, B	MAGNESIUM ION Mg JLVVSXFLKOJNIY-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.30 Å
• R-Value Free: 0.214 
• R-Value Work: 0.165 
• R-Value Observed: 0.165 
• Space Group: C 2 2 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 116.822	α = 90
b = 160.573	β = 90
c = 129.374	γ = 90

Software Package:

Software Name	Purpose
ADSC	data collection
SCALEPACK	data scaling
AMoRE	phasing
CNS	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2003-04-09 
• Released Date: 2003-11-11 
Deposition Author(s): Pang, S.S., Duggleby, R.G., Schowen, R.L., Guddat, L.W.

Revision History 

• Version 1.0: 2003-11-11
  Type: Initial release
  
• Version 1.1: 2008-04-29
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Derived calculations, Version format compliance