Abstract
Oxalacetate acetylhydrolase (OAH), a member of the phosphoenolpyruvate mutase/isocitrate lyase superfamily, catalyzes the hydrolysis of oxalacetate to oxalic acid and acetate. This study shows that knock-out of the oah gene in Cryphonectria parasitica, the chestnut blight fungus, reduces the ability of the fungus to form cankers on chestnut trees, suggesting that OAH plays a key role in virulence. OAH was produced in Escherichia coli and purified, and its catalytic rates were determined. Oxalacetate is the main OAH substrate, but the enzyme also acts as a lyase of (2R,3S)-dimethyl malate with approximately 1000-fold lower efficacy. The crystal structure of OAH was determined alone, in complex with a mechanism-based inhibitor, 3,3-difluorooxalacetate (DFOA), and in complex with the reaction product, oxalate, to a resolution limit of 1.30, 1.55, and 1.65 A, respectively. OAH assembles into a dimer of dimers with each subunit exhibiting an (alpha/beta)(8) barrel fold and each pair swapping the 8th alpha-helix. An active site "gating loop" exhibits conformational disorder in the ligand-free structure. To obtain the structures of the OAH.ligand complexes, the ligand-free OAH crystals were soaked briefly with DFOA or oxalacetate. DFOA binding leads to ordering of the gating loop in a conformation that sequesters the ligand from the solvent. DFOA binds in a gem-diol form analogous to the oxalacetate intermediate/transition state. Oxalate binds in a planar conformation, but the gating loop is largely disordered. Comparison between the OAH structure and that of the closely related enzyme, 2,3-dimethylmalate lyase, suggests potential determinants of substrate preference.
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Claims 13
Claim · model-written summary
Deleting fungal oah reduced canker formation on chestnut trees.
- Taxon
- chestnut treese0
- Treatment
- knock-out of the oah genee0
- Interactor
- Cryphonectria parasitica
Cryphonectria parasiticae0pathogen - Gene
- oahe0
- Outcome
- ability of the fungus to form cankerse0
- Direction
- reducese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“knock-out of the oah gene in Cryphonectria parasitica, the chestnut blight fungus, reduces the ability of the fungus to form cankers on chestnut trees”
Claim · model-written summary
The authors infer a key role for OAH in fungal virulence.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae0
- Gene
- OAHe0
- Outcome
- virulencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cryphonectria parasitica, the chestnut blight fungus, reduces the ability of the fungus to form cankers on chestnut trees, suggesting that OAH plays a key role in virulence.”
Claim · model-written summary
Oxalacetate is the principal OAH substrate.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Gene
- OAHe0
- Compound
- Oxalacetatee0
- Outcome
- main OAH substratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxalacetate is the main OAH substrate”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
OAH also acts as a dimethyl malate lyase with approximately 1000-fold lower efficacy.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Gene
- OAHe0
- Compound
- (2R,3S)-dimethyl malatee0
- Outcome
- efficacye0
- Direction
- lowere0
- Value
- approximately 1000-folde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxalacetate is the main OAH substrate, but the enzyme also acts as a lyase of (2R,3S)-dimethyl malate with approximately 1000-fold lower efficacy.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
The uncomplexed OAH crystal structure was determined at 1.30 A resolution.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Outcome
- crystal structure of OAHe0
- Value
- 1.30e0
- Qualifier
- alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The crystal structure of OAH was determined alone, in complex with a mechanism-based inhibitor, 3,3-difluorooxalacetate (DFOA), and in complex with the reaction product, oxalate, to a resolution limit of 1.30, 1.55, and 1.65 A, respectively.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
The OAH inhibitor complex crystal structure was determined at 1.55 A resolution.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Compound
- 3,3-difluorooxalacetatee0
- Outcome
- crystal structure of OAHe0
- Value
- 1.55e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The crystal structure of OAH was determined alone, in complex with a mechanism-based inhibitor, 3,3-difluorooxalacetate (DFOA), and in complex with the reaction product, oxalate, to a resolution limit of 1.30, 1.55, and 1.65 A, respectively.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
The OAH oxalate complex crystal structure was determined at 1.65 A resolution.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Compound
- oxalatee0
- Outcome
- crystal structure of OAHe0
- Value
- 1.65 Ae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The crystal structure of OAH was determined alone, in complex with a mechanism-based inhibitor, 3,3-difluorooxalacetate (DFOA), and in complex with the reaction product, oxalate, to a resolution limit of 1.30, 1.55, and 1.65 A, respectively.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
OAH forms a dimer of dimers, with barrel-fold subunits and paired exchange of the eighth alpha helix.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Gene
- OAHe0
- Outcome
- dimer of dimerse0
- Qualifier
- each subunit exhibiting an (alpha/beta)(8) barrel fold and each pair swapping the 8th alpha-helixe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“OAH assembles into a dimer of dimers with each subunit exhibiting an (alpha/beta)(8) barrel fold and each pair swapping the 8th alpha-helix.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
The active-site gating loop is conformationally disordered without ligand.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Outcome
- conformational disordere0
- Qualifier
- ligand-free structuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“An active site "gating loop" exhibits conformational disorder in the ligand-free structure.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
DFOA binding orders the gating loop so that the ligand is sequestered from solvent.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Treatment
- DFOA bindinge0
- Outcome
- ordering of the gating loope0
- Qualifier
- sequesters the ligand from the solvente0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DFOA binding leads to ordering of the gating loop in a conformation that sequesters the ligand from the solvent.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
DFOA binds as a gem-diol resembling the oxalacetate intermediate or transition state.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Compound
- DFOAe0
- Outcome
- gem-diol forme0
- Qualifier
- analogous to the oxalacetate intermediate/transition statee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DFOA binds in a gem-diol form analogous to the oxalacetate intermediate/transition state.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
Oxalate binds in a planar conformation while the gating loop remains largely disordered.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Compound
- Oxalatee0
- Outcome
- planar conformatione0
- Qualifier
- gating loop is largely disorderede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oxalate binds in a planar conformation, but the gating loop is largely disordered.”
e1“oah gene in Cryphonectria parasitica”
Claim · model-written summary
Structural comparison with dimethylmalate lyase suggests potential determinants of substrate preference.
- Taxon
- Cryphonectria parasiticaCryphonectria parasiticae1
- Gene
- OAHe0
- Outcome
- potential determinants of substrate preferencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison between the OAH structure and that of the closely related enzyme, 2,3-dimethylmalate lyase, suggests potential determinants of substrate preference.”
e1“oah gene in Cryphonectria parasitica”
The same questions in other papers
loss of function · Cryphonectria parasitica · CastaneaResults agree
2 papers in the same direction as this paper
- positive
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.