5WJ1

Crystal structure of Arabidopsis thaliana acetohydroxyacid synthase in complex with a triazolopyrimidine herbicide, penoxsulam


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.52 Å
  • R-Value Free: 0.165 
  • R-Value Work: 0.140 
  • R-Value Observed: 0.141 

Starting Model: experimental
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Ligand Structure Quality Assessment 


This is version 1.4 of the entry. See complete history


Literature

Structural insights into the mechanism of inhibition of AHAS by herbicides.

Lonhienne, T.Garcia, M.D.Pierens, G.Mobli, M.Nouwens, A.Guddat, L.W.

(2018) Proc Natl Acad Sci U S A 115: E1945-E1954

  • DOI: https://doi.org/10.1073/pnas.1714392115
  • Primary Citation of Related Structures:  
    5WJ1, 5WKC

  • PubMed Abstract: 

    Acetohydroxyacid synthase (AHAS), the first enzyme in the branched amino acid biosynthesis pathway, is present only in plants and microorganisms, and it is the target of >50 commercial herbicides. Penoxsulam (PS), which is a highly effective broad-spectrum AHAS-inhibiting herbicide, is used extensively to control weed growth in rice crops. However, the molecular basis for its inhibition of AHAS is poorly understood. This is despite the availability of structural data for all other classes of AHAS-inhibiting herbicides. Here, crystallographic data for Saccharomyces cerevisiae AHAS (2.3 Å) and Arabidopsis thaliana AHAS (2.5 Å) in complex with PS reveal the extraordinary molecular mechanisms that underpin its inhibitory activity. The structures show that inhibition of AHAS by PS triggers expulsion of two molecules of oxygen bound in the active site, releasing them as substrates for an oxygenase side reaction of the enzyme. The structures also show that PS either stabilizes the thiamin diphosphate (ThDP)-peracetate adduct, a product of this oxygenase reaction, or traps within the active site an intact molecule of peracetate in the presence of a degraded form of ThDP: thiamine aminoethenethiol diphosphate. Kinetic analysis shows that PS inhibits AHAS by a combination of events involving FAD oxidation and chemical alteration of ThDP. With the emergence of increasing levels of resistance toward front-line herbicides and the need to optimize the use of arable land, these data suggest strategies for next generation herbicide design.


  • Organizational Affiliation

    School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia; t.lonhienne@uq.edu.au luke.guddat@uq.edu.au.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Acetolactate synthase, chloroplastic590Arabidopsis thalianaMutation(s): 0 
Gene Names: ALSAHASCSR1TZP5At3g48560T8P19.70
EC: 2.2.1.6
UniProt
Find proteins for P17597 (Arabidopsis thaliana)
Explore P17597 
Go to UniProtKB:  P17597
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP17597
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 6 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
FAD
Query on FAD

Download Ideal Coordinates CCD File 
C [auth A]FLAVIN-ADENINE DINUCLEOTIDE
C27 H33 N9 O15 P2
VWWQXMAJTJZDQX-UYBVJOGSSA-N
PXD
Query on PXD

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E [auth A]2-(2,2-difluoroethoxy)-N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)-6-(trifluoromethyl)benzenesulfonamide
C16 H14 F5 N5 O5 S
SYJGKVOENHZYMQ-UHFFFAOYSA-N
TP9 (Subject of Investigation/LOI)
Query on TP9

Download Ideal Coordinates CCD File 
G [auth A](3Z)-4-{[(4-AMINO-2-METHYLPYRIMIDIN-5-YL)METHYL]AMINO}-3-MERCAPTOPENT-3-EN-1-YL TRIHYDROGEN DIPHOSPHATE
C11 H18 N4 O7 P2 S
WTQDUFKDQLXDPH-YFHOEESVSA-L
F50
Query on F50

Download Ideal Coordinates CCD File 
F [auth A]ETHANEPEROXOIC ACID
C2 H4 O3
KFSLWBXXFJQRDL-UHFFFAOYSA-N
K
Query on K

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D [auth A]POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
MG
Query on MG

Download Ideal Coordinates CCD File 
B [auth A]MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.52 Å
  • R-Value Free: 0.165 
  • R-Value Work: 0.140 
  • R-Value Observed: 0.141 
  • Space Group: P 64 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 179.957α = 90
b = 179.957β = 90
c = 185.35γ = 120
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
Aimlessdata scaling
PHASERphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Health and Medical Research Council (NHMRC, Australia)Australia1008736

Revision History  (Full details and data files)

  • Version 1.0: 2018-02-14
    Type: Initial release
  • Version 1.1: 2018-02-28
    Changes: Database references
  • Version 1.2: 2018-03-07
    Changes: Database references
  • Version 1.3: 2020-01-08
    Changes: Author supporting evidence
  • Version 1.4: 2023-10-04
    Changes: Data collection, Database references, Derived calculations, Refinement description