Abstract
The first committed step in the biosynthesis of indole glucosinolates is the conversion of indole-3-acetaldoxime into an indole-3-S-alkyl-thiohydroximate. The initial step in this conversion is catalyzed by CYP83B1 in Arabidopsis (S. Bak, F.E. Tax, K.A. Feldmann, D.A. Galbraith, R. Feyereisen [2001] Plant Cell 13: 101-111). The knockout mutant of the CYP83B1 gene (rnt1-1) shows a strong auxin excess phenotype and are allelic to sur-2. CYP83A1 is the closest relative to CYP83B1 and shares 63% amino acid sequence identity. Although expression of CYP83A1 under control of its endogenous promoter in the rnt1-1 background does not prevent the auxin excess and indole glucosinolate deficit phenotype caused by the lack of the CYP83B1 gene, ectopic overexpression of CYP83A1 using a 35S promoter rescues the rnt1-1 phenotype. CYP83A1 and CYP83B1 heterologously expressed in yeast (Saccharomyces cerevisiae) cells show marked differences in their substrate specificity. Both enzymes convert indole-3-acetaldoxime to a thiohydroximate adduct in the presence of NADPH and a nucleophilic thiol donor. However, indole-3-acetaldoxime has a 50-fold higher affinity toward CYP83B1 than toward CYP83A1. Both enzymes also metabolize the phenylalanine- and tyrosine-derived aldoximes. Enzyme kinetic comparisons of CYP83A1 and CYP83B1 show that indole-3-acetaldoxime is the physiological substrate for CYP83B1 but not for CYP83A1. Instead, CYP83A1 catalyzes the initial conversion of aldoximes to thiohydroximates in the synthesis of glucosinolates not derived from tryptophan. The two closely related CYP83 subfamily members therefore are not redundant. The presence of putative auxin responsive cis-acting elements in the CYP83B1 promoter but not in the CYP83A1 promoter supports the suggestion that CYP83B1 has evolved to selectively metabolize a tryptophan-derived aldoxime intermediate shared with the pathway of auxin biosynthesis in Arabidopsis.
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Claims 10
Claim · model-written summary
CYP83A1 and CYP83B1 share 63% amino acid sequence identity.
- Taxon
- Arabidopsis
Arabidopsise1 - Gene
- CYP83A1e0
- Outcome
- amino acid sequence identitye0
- Value
- 63%e0
- Comparator
- CYP83B1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYP83A1 is the closest relative to CYP83B1 and shares 63% amino acid sequence identity”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Endogenous-promoter CYP83A1 expression did not prevent the auxin excess phenotype of rnt1-1.
- Taxon
- ArabidopsisArabidopsise1
- Material
- rnt1-1e0
- Treatment
- expression of CYP83A1 under control of its endogenous promotere0
- Gene
- CYP83A1e0
- Outcome
- auxin excesse0
- Direction
- does not prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of CYP83A1 under control of its endogenous promoter in the rnt1-1 background does not prevent the auxin excess and indole glucosinolate deficit phenotype”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Endogenous-promoter CYP83A1 expression did not prevent the indole glucosinolate deficit of rnt1-1.
- Taxon
- ArabidopsisArabidopsise1
- Material
- rnt1-1e0
- Treatment
- expression of CYP83A1 under control of its endogenous promotere0
- Gene
- CYP83A1e0
- Outcome
- indole glucosinolate deficite0
- Direction
- does not prevente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression of CYP83A1 under control of its endogenous promoter in the rnt1-1 background does not prevent the auxin excess and indole glucosinolate deficit phenotype”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Ectopic CYP83A1 overexpression rescued the rnt1-1 phenotype.
- Taxon
- ArabidopsisArabidopsise1
- Material
- rnt1-1e0
- Treatment
- ectopic overexpression of CYP83A1 using a 35S promotere0
- Gene
- CYP83A1e0
- Outcome
- rnt1-1 phenotypee0
- Direction
- rescuese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ectopic overexpression of CYP83A1 using a 35S promoter rescues the rnt1-1 phenotype”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
CYP83A1 and CYP83B1 both convert indole-3-acetaldoxime to a thiohydroximate adduct.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83A1 and CYP83B1e0
- Compound
- indole-3-acetaldoximee0
- Outcome
- thiohydroximate adducte0
- Qualifier
- in the presence of NADPH and a nucleophilic thiol donore0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYP83A1 and CYP83B1 heterologously expressed in yeast (Saccharomyces cerevisiae) cells show marked differences in their substrate specificity. Both enzymes convert indole-3-acetaldoxime to a thiohydroximate adduct in the presence of NADPH and a nucleophilic thiol donor”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Indole-3-acetaldoxime had 50-fold greater affinity for CYP83B1 than CYP83A1.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83B1e0
- Compound
- indole-3-acetaldoximee0
- Outcome
- affinitye0
- Direction
- highere0
- Value
- 50-folde0
- Comparator
- CYP83A1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indole-3-acetaldoxime has a 50-fold higher affinity toward CYP83B1 than toward CYP83A1”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Both CYP83 enzymes metabolized phenylalanine- and tyrosine-derived aldoximes.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83A1 and CYP83B1e0
- Outcome
- phenylalanine- and tyrosine-derived aldoximese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYP83A1 and CYP83B1 heterologously expressed in yeast (Saccharomyces cerevisiae) cells show marked differences in their substrate specificity. Both enzymes convert indole-3-acetaldoxime to a thiohydroximate adduct in the presence of NADPH and a nucleophilic thiol donor. However, indole-3-acetaldoxime has a 50-fold higher affinity toward CYP83B1 than toward CYP83A1. Both enzymes also metabolize the phenylalanine- and tyrosine-derived aldoximes”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Indole-3-acetaldoxime was identified as the physiological substrate of CYP83B1 but not CYP83A1.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83B1e0
- Compound
- indole-3-acetaldoximee0
- Outcome
- physiological substratee0
- Comparator
- CYP83A1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“indole-3-acetaldoxime is the physiological substrate for CYP83B1 but not for CYP83A1”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
CYP83A1 catalyzed initial aldoxime conversion for glucosinolates not derived from tryptophan.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83A1e0
- Outcome
- conversion of aldoximes to thiohydroximatese0
- Qualifier
- glucosinolates not derived from tryptophane0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CYP83A1 catalyzes the initial conversion of aldoximes to thiohydroximates in the synthesis of glucosinolates not derived from tryptophan”
e1“CYP83B1 in Arabidopsis”
Claim · model-written summary
Putative auxin-responsive promoter elements were present in CYP83B1 but absent from CYP83A1.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- CYP83B1e0
- Outcome
- putative auxin responsive cis-acting elementse0
- Comparator
- CYP83A1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The presence of putative auxin responsive cis-acting elements in the CYP83B1 promoter but not in the CYP83A1 promoter”
e1“CYP83B1 in Arabidopsis”
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