Crystal structure of Candida albicans acetohydroxyacid synthase catalytic subunit

Experimental Data Snapshot

  • Resolution: 2.97 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.153 
  • R-Value Observed: 0.155 

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This is version 1.4 of the entry. See complete history


Commercial AHAS-inhibiting herbicides are promising drug leads for the treatment of human fungal pathogenic infections.

Garcia, M.D.Chua, S.M.H.Low, Y.S.Lee, Y.T.Agnew-Francis, K.Wang, J.G.Nouwens, A.Lonhienne, T.Williams, C.M.Fraser, J.A.Guddat, L.W.

(2018) Proc Natl Acad Sci U S A 115: E9649-E9658

  • DOI: https://doi.org/10.1073/pnas.1809422115
  • Primary Citation of Related Structures:  
    6DEK, 6DEL, 6DEM, 6DEN, 6DEO, 6DEP, 6DEQ, 6DER, 6DES

  • PubMed Abstract: 

    The increased prevalence of drug-resistant human pathogenic fungal diseases poses a major threat to global human health. Thus, new drugs are urgently required to combat these infections. Here, we demonstrate that acetohydroxyacid synthase (AHAS), the first enzyme in the branched-chain amino acid biosynthesis pathway, is a promising new target for antifungal drug discovery. First, we show that several AHAS inhibitors developed as commercial herbicides are powerful accumulative inhibitors of Candida albicans AHAS ( K i values as low as 800 pM) and have determined high-resolution crystal structures of this enzyme in complex with several of these herbicides. In addition, we have demonstrated that chlorimuron ethyl (CE), a member of the sulfonylurea herbicide family, has potent antifungal activity against five different Candida species and Cryptococcus neoformans (with minimum inhibitory concentration, 50% values as low as 7 nM). Furthermore, in these assays, we have shown CE and itraconazole (a P450 inhibitor) can act synergistically to further improve potency. Finally, we show in Candida albicans -infected mice that CE is highly effective in clearing pathogenic fungal burden in the lungs, liver, and spleen, thus reducing overall mortality rates. Therefore, in view of their low toxicity to human cells, AHAS inhibitors represent a new class of antifungal drug candidates.

  • Organizational Affiliation

    School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Acetolactate synthase682Candida albicans SC5314Mutation(s): 0 
Gene Names: ILV2orf19.1613CAALFM_C302320WA
Find proteins for A0A1D8PJF9 (Candida albicans (strain SC5314 / ATCC MYA-2876))
Explore A0A1D8PJF9 
Go to UniProtKB:  A0A1D8PJF9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupA0A1D8PJF9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.97 Å
  • R-Value Free: 0.186 
  • R-Value Work: 0.153 
  • R-Value Observed: 0.155 
  • Space Group: P 62 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 176.039α = 90
b = 176.039β = 90
c = 177.626γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
XDSdata scaling

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: 2018-09-26
    Type: Initial release
  • Version 1.1: 2018-10-10
    Changes: Data collection, Database references, Structure summary
  • Version 1.2: 2018-10-17
    Changes: Data collection, Database references, Structure summary
  • Version 1.3: 2020-01-08
    Changes: Author supporting evidence
  • Version 1.4: 2023-10-11
    Changes: Data collection, Database references, Refinement description