Biological Assembly 1  

 3D View: Structure | Electron Density | Ligand Interaction

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

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

Macromolecule Content

• Total Structure Weight: 150.41 kDa 
• Atom Count: 10553 
• Modelled Residue Count: 1178 
• Deposited Residue Count: 1354 
• Unique protein chains: 1

1T9B

Crystal structure of yeast acetohydroxyacid synthase in complex with a sulfonylurea herbicide, chlorsulfuron

• DOI: 10.2210/pdb1T9B/pdb

• Classification: TRANSFERASE
• Organism(s): Saccharomyces cerevisiae
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2004-05-16 Released: 2004-12-21 
• Deposition Author(s): McCourt, J.A., Pang, S.S., Guddat, L.W., Duggleby, R.G.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.20 Å
• R-Value Free: 0.195 
• R-Value Work: 0.162 
• R-Value Observed: 0.165 

Literature

Elucidating the specificity of binding of sulfonylurea herbicides to acetohydroxyacid synthase.

McCourt, J.A., Pang, S.S., Guddat, L.W., Duggleby, R.G.

(2005) Biochemistry 44: 2330-2338

• PubMed: 15709745 
• DOI: 10.1021/bi047980a
• Primary Citation of Related Structures:  
  1T9D, 1T9C, 1T9B, 1T9A


• PubMed Abstract: 
  

Acetohydroxyacid synthase (AHAS, EC 2.2.1.6) is the target for the sulfonylurea herbicides, which act as potent inhibitors of the enzyme. Chlorsulfuron (marketed as Glean) and sulfometuron methyl (marketed as Oust) are two commercially important members of this family of herbicides. Here we report crystal structures of yeast AHAS in complex with chlorsulfuron (at a resolution of 2.19 A), sulfometuron methyl (2.34 A), and two other sulfonylureas, metsulfuron methyl (2.29 A) and tribenuron methyl (2.58 A). The structures observed suggest why these inhibitors have different potencies and provide clues about the differential effects of mutations in the active site tunnel on various inhibitors. In all of the structures, the thiamin diphosphate cofactor is fragmented, possibly as the result of inhibitor binding. In addition to thiamin diphosphate, AHAS requires FAD for activity. Recently, it has been reported that reduction of FAD can occur as a minor side reaction due to reaction with the carbanion/enamine of the hydroxyethyl-ThDP intermediate that is formed midway through the catalytic cycle. Here we report that the isoalloxazine ring has a bent conformation that would account for its ability to accept electrons from the hydroxyethyl intermediate. Most sequence and mutation data suggest that yeast AHAS is a high-quality model for the plant enzyme.

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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, mitochondrial	A, B	677	Saccharomyces cerevisiae	Mutation(s): 0  Gene Names: ILV2, SMR1, YMR108W, YM9718.07 EC: 2.2.1.6
Find proteins for P07342 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c)) Explore P07342  Go to UniProtKB:  P07342

Small Molecules

Ligands 8 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
FAD	F [auth A], N [auth B]	FLAVIN-ADENINE DINUCLEOTIDE C27 H33 N9 O15 P2 VWWQXMAJTJZDQX-UYBVJOGSSA-N
1CS	E [auth A], M [auth B]	1-(2-CHLOROPHENYLSULFONYL)-3-(4-METHOXY-6-METHYL-L,3,5-TRIAZIN-2-YL)UREA C12 H12 Cl N5 O4 S VJYIFXVZLXQVHO-UHFFFAOYSA-N
P25	L [auth B]	PENTYL TRIHYDROGEN DIPHOSPHATE C5 H14 O7 P2 VFFCVKZHJFIUBM-UHFFFAOYSA-N
YF3	I [auth A]	2-{[(4-AMINO-2-METHYLPYRIMIDIN-5-YL)METHYL]AMINO}PROPANE-1-THIOL C9 H16 N4 S BGGAKPFEDJLRDQ-UHFFFAOYSA-N
P22	H [auth A]	ETHYL DIHYDROGEN DIPHOSPHATE C2 H8 O7 P2 OJDJHGIXNZPZFD-UHFFFAOYSA-N
NSP	G [auth A]	5-(AMINOMETHYL)-2-METHYLPYRIMIDIN-4-AMINE C6 H10 N4 OZOHTVFCSKFMLL-UHFFFAOYSA-N
K	C [auth A], J [auth B]	POTASSIUM ION K NPYPAHLBTDXSSS-UHFFFAOYSA-N
MG	D [auth A], K [auth B]	MAGNESIUM ION Mg JLVVSXFLKOJNIY-UHFFFAOYSA-N

External Ligand Annotations
ID	Binding Affinity (Sequence Identity %)
1CS	Ki:  127   nM  Binding MOAD
1CS	Ki:  127   nM  BindingDB

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.20 Å
• R-Value Free: 0.195 
• R-Value Work: 0.162 
• R-Value Observed: 0.165 
• Space Group: P 4 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 154.579	α = 90
b = 154.579	β = 90
c = 178.759	γ = 90

Software Package:

Software Name	Purpose
Adxv	data processing
SCALEPACK	data scaling
AMoRE	phasing
CNS	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2004-05-16 
• Released Date: 2004-12-21 
Deposition Author(s): McCourt, J.A., Pang, S.S., Guddat, L.W., Duggleby, R.G.

Revision History  

• Version 1.0: 2004-12-21
  Type: Initial release
  
• Version 1.1: 2008-04-30
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2017-10-11
  Changes: Refinement description