Substrate Specificity of the Cytochrome P450 Enzymes CYP79A1 and CYP71E1 Involved in the Biosynthesis of the Cyanogenic Glucoside Dhurrin inSorghum bicolor(L.) Moench

Kahn, Rachel Alice; Fahrendorf, Theodor; Halkier, Barbara Ann; Møller, Birger Lindberg

doi:10.1006/abbi.1998.1068

Cited by 92 publications

(55 citation statements)

References 30 publications

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“…In addition, when [ 14 C]tyrosine or [ 14 C]indole was substituted for [ 14 C]tryptophan, no novel spots were detected (data not shown). These results suggest that CYP79B2 is specific for Trp; strict substrate specificity also has been observed for CYP79A1 (28). Two lines of evidence suggest that the product generated by CYP79B2 in E. coli extracts is IAOx.…”

Section: Cyp79b2 Metabolizes Trp To Iaox In Vitromentioning

confidence: 58%

Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis

Hull

Vij

Celenza

2000

Proc. Natl. Acad. Sci. U.S.A.

437

331

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Plants synthesize numerous secondary metabolites that are used as developmental signals or as defense against pathogens. Tryptophan (Trp)-derived secondary metabolites include camalexin, indole glucosinolates, and indole-3-acetic acid (IAA); however, the steps in their synthesis from Trp or its precursors remain unclear. We have identified two Arabidopsis cytochrome P450s (CYP79B2 and CYP79B3) that can convert Trp to indole-3-acetaldoxime (IAOx), a precursor to IAA and indole glucosinolates.auxin ͉ metabolism ͉ glucosinolates

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Section: Cyp79b2 Metabolizes Trp To Iaox In Vitromentioning

confidence: 58%

Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis

Hull

Vij

Celenza

2000

Proc. Natl. Acad. Sci. U.S.A.

437

331

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“…10). There is an example of a plant UGT whose actual substrate in vivo is determined by the substrate specificity of interacting enzymes that catalyze upstream reactions (Sorghum bicolor UGT85B1; Kahn et al, 1999;Nielsen et al, 2008). We can hypothesize that the cZOGTs interact with other proteins affecting the in vivo activity of cZOGTs.…”

Section: Discussionmentioning

confidence: 99%

Cytokinin Activity of cis-Zeatin and Phenotypic Alterations Induced by Overexpression of Putative cis-Zeatin-O-glucosyltransferase in Rice

et al. 2012

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cis-Zeatin (cZ) is generally regarded as a cytokinin with little or no activity, compared with the highly active trans-zeatin (tZ). Although recent studies suggested possible roles for cZ, its physiological significance remains unclear. In our studies with rice (Oryza sativa), cZ inhibited seminal root elongation and up-regulated cytokinin-inducible genes, and its activities were comparable to those of tZ. Tracer experiments showed that exogenously supplied cZ-riboside was mainly converted into cZ derivatives but scarcely into tZ derivatives, indicating that isomerizations of cZ derivatives into tZ derivatives are a minor pathway in rice cytokinin metabolism. We identified three putative cZ-O-glucosyltransferases (cZOGT1, cZOGT2, and cZOGT3) in rice. The cZOGTs preferentially catalyzed O-glucosylation of cZ and cZ-riboside rather than tZ and tZ-riboside in vitro. Transgenic rice lines ectopically overexpressing the cZOGT1 and cZOGT2 genes exhibited short-shoot phenotypes, delay of leaf senescence, and decrease in crown root number, while cZOGT3 overexpressor lines did not show shortened shoots. These results propose that cZ activity has a physiological impact on the growth and development of rice.

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“…Detection of direct binding of oximes to P450 enzymes has been reported to be difficult (Boucher et al, 1994;Kahn et al, 1999;Bak et al, 2001). As an alternative method that has been applied in similar situations, we tested if the binding of substrate could be measured as the ability to displace tryptamine from the active site (Jefcoate, 1978;Bak et al, 2001).…”

Section: Spectral Characterization Of Recombinant Cyp71a13mentioning

confidence: 99%

ArabidopsisCytochrome P450 Monooxygenase 71A13 Catalyzes the Conversion of Indole-3-Acetaldoxime in Camalexin Synthesis

Goregaoker²,

et al. 2007

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Camalexin (3-thiazol-2-yl-indole) is an indole alkaloid phytoalexin produced by Arabidopsis thaliana that is thought to be important for resistance to necrotrophic fungal pathogens, such as Alternaria brassicicola and Botrytis cinerea. It is produced from Trp, which is converted to indole acetaldoxime (IAOx) by the action of cytochrome P450 monooxygenases CYP79B2 and CYP79B3. The remaining biosynthetic steps are unknown except for the last step, which is conversion of dihydrocamalexic acid to camalexin by CYP71B15 (PAD3). This article reports characterization of CYP71A13. Plants carrying cyp71A13 mutations produce greatly reduced amounts of camalexin after infection by Pseudomonas syringae or A. brassicicola and are susceptible to A. brassicicola, as are pad3 and cyp79B2 cyp79B3 mutants. Expression levels of CYP71A13 and PAD3 are coregulated. CYP71A13 expressed in Escherichia coli converted IAOx to indole-3-acetonitrile (IAN). Expression of CYP79B2 and CYP71A13 in Nicotiana benthamiana resulted in conversion of Trp to IAN. Exogenously supplied IAN restored camalexin production in cyp71A13 mutant plants. Together, these results lead to the conclusion that CYP71A13 catalyzes the conversion of IAOx to IAN in camalexin synthesis and provide further support for the role of camalexin in resistance to A. brassicicola.

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Substrate Specificity of the Cytochrome P450 Enzymes CYP79A1 and CYP71E1 Involved in the Biosynthesis of the Cyanogenic Glucoside Dhurrin inSorghum bicolor(L.) Moench

Cited by 92 publications

References 30 publications

Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis

Arabidopsis cytochrome P450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis

Cytokinin Activity of cis-Zeatin and Phenotypic Alterations Induced by Overexpression of Putative cis-Zeatin-O-glucosyltransferase in Rice

ArabidopsisCytochrome P450 Monooxygenase 71A13 Catalyzes the Conversion of Indole-3-Acetaldoxime in Camalexin Synthesis

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