A Phosphoribosylanthranilate Transferase Gene Is Defective in Blue Fluorescent <i>Arabidopsis thaliana</i> Tryptophan Mutants

Rose, Alan B.; Casselman, Amy L.

doi:10.1104/pp.100.2.582

Cited by 78 publications

(61 citation statements)

References 34 publications

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“…The chromosomal location of the CKR1 gene was determined by measuring the recombination frequency between the mutation and CAPS that mark different Arabidopsis chromosomes (Konieczny and Ausubel, 1993). The CKR1 gene was located at the top of chromosome 5, and the map position was further refined by scoring the recombination frequency relative to nearby markers on chromosome 5, RFLP marker AR119 (Rose et al, 1992), and a CAPS marker generated from the published sequence of CTR1 . The CTR1 CAPS marker was amplified with oligonucleotide primers, 5'-CGATCCTGCATCAGGTAT-TCC-3' and 5'-CTTACTTAGACGCGAAGGC-3', and cleaved with Bell.…”

Section: Ckr1 Gene Mappingmentioning

confidence: 99%

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

1995

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and Ecker, 1990). Some of these features have been utilized in the isolation of mutants with altered responses to ethylene . Ethylene-resistant mutants (ein or etr mutants) were identified by selecting seedlings that fail to express the triple response in the presente of ethylene. Other mutants were identified that pr0duc-d a triple-response phenotype constitutively, i.e. when no ethylene was applied. These mutants have been grouped into two classes, ethylene overproducers (eto) and constitutive triple-response mutants (ctr), distinguished on the basis of whether the phenotype is suppressed by inhibitors Of ethYlene biosynthesis Or action (Guzmán and Eckerr l990). Through epistasis analysis of the mutants, ethylene-response genes have been ordered on an unbranched pathway . Interestingly, ein or etr mutants appear to have very little effect on the normal growth and development of light-grown Arabidopsis seedlings in the absence of supplied ethylene.We have examined the relationship between cytokinin and ethylene responses in Arabidopsis seedlings and have found that ethylene largely mediates a number of responses to exogenous cytokinin, such as the inhibition of root and hypocotyl elongation. Cytokinin stimulates ethylene production, which, in turn, inhibits root and darkgrown hypocotyl elongation. Because of that, the effects of cytokinin on root and hypocotyl elongation can be blocked, in part, by the action of ethylene inhibitors or by ethylene mutants. These results constitute genetic proof of the idea put forth by Lieberman (1979) that cytokinin is coupled to ethylene action in seedlings.Cytokinins have profound effects on seedling development in Arabidopsis thaliana. Benzyladenine (BA) inhibits root elongation in light-or dark-grown seedlings, and in dark-grown seedlings BA inhibits hypocotyl elongation and exaggerates the curvature of apical hooks. The latter are characteristic ethylene responses and, therefore, the possible involvement of ethylene in BA responses was examined in seedlings. It was found that the inhibitory effects of BA on root and hypocotyl elongation were partially blocked by the action of ethylene inhibitors or ethylene-resistant mutations (ein7-7 and ein2-7). Ethylene production was stimulated by submicromolar concentrations of BA and could account, in part, for the inhibition of root and hypocotyl elongation. It was demonstrated further that BA did not affect the sensitivity of seedlings to ethylene. Thus, the effect of cytokinin on root and hypocotyl elongation in Arabidopsis appears to be mediated largely by the production of ethylene. The coupling between cytokinin and ethylene responses is further SUPported by the discovery that the cytokinin-resistant mutant ckrl is resistant to ethylene and is allelic to the ethylene-resistant mutant ein2.The responses of seedlings to developmental and environmental cues have been useful in studying signal transduction pathways in plants. Arabidopsis thaliana seedlings respond to exogenously added or endogenous cytokinins, and in light-grown se...

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Section: Ckr1 Gene Mappingmentioning

confidence: 99%

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

1995

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“…The genes for all of the enzymes that catalyze the steps in the conversion of chorismate to Trp, including anthranilate synthase (AS), phosphoribosylanthranilate transferase, phosphoribosylanthranilate isomerase, indole-3-glycerol phosphate synthase, and Trp synthase, have been identified in the Trp biosynthetic pathway (Last et al, 1991;Niyogi and Fink, 1992;Rose et al, 1992;Niyogi et al, 1993;Li et al, 1995aLi et al, , 1995bRadwanski et al, 1995). Mutations of the gene for an a-subunit of AS, which catalyzes the conversion of chorismate to anthranilate and is feedback regulated by Trp, have been shown to generate a feedback-insensitive form of the enzyme that results in the accumulation of Trp in Arabidopsis thaliana (Li and Last, 1996).…”

Section: Introductionmentioning

confidence: 99%

Mutation of a Rice Gene Encoding a Phenylalanine Biosynthetic Enzyme Results in Accumulation of Phenylalanine and Tryptophan

et al. 2008

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Two distinct biosynthetic pathways for Phe in plants have been proposed: conversion of prephenate to Phe via phenylpyruvate or arogenate. The reactions catalyzed by prephenate dehydratase (PDT) and arogenate dehydratase (ADT) contribute to these respective pathways. The Mtr1 mutant of rice (Oryza sativa) manifests accumulation of Phe, Trp, and several phenylpropanoids, suggesting a link between the synthesis of Phe and Trp. Here, we show that the Mtr1 mutant gene (mtr1-D) encodes a form of rice PDT with a point mutation in the putative allosteric regulatory region of the protein. Transformed callus lines expressing mtr1-D exhibited all the characteristics of Mtr1 callus tissue. Biochemical analysis revealed that rice PDT possesses both PDT and ADT activities, with a preference for arogenate as substrate, suggesting that it functions primarily as an ADT. The wild-type enzyme is feedback regulated by Phe, whereas the mutant enzyme showed a reduced feedback sensitivity, resulting in Phe accumulation. In addition, these observations indicate that rice PDT is critical for regulating the size of the Phe pool in plant cells. Feeding external Phe to wild-type callus tissue and seedlings resulted in Trp accumulation, demonstrating a connection between Phe accumulation and Trp pool size.

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“…The trp1-100 mutation is caused by a serine to asparagine mutation at codon 224 of the PAT1 gene, which encodes phosphoribosylanthranilate transferase (15). This defect confers strong fluorescence in cotyledons and weaker fluorescence in adult plant tissues without any additional morphological or fertility defects (14). The trp1-100 fluorescence phenotype is caused by accumulation of glucose-conjugated anthranilate (6).…”

Section: Resultsmentioning

confidence: 99%

“…This reporter phenotype has also been exploited to study factors that regulate cytosine methylation and gene silencing in plants (10 -13). For example, a blue fluorescence Arabidopsis mutation, the weak trp1-100 allele in the gene encoding the second enzyme of the pathway (14,15), was used to identify second site mutations that block the production of fluorescent compounds (7). In this work, the goal was to recover mutations that impair the synthesis of anthranilate.…”

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confidence: 99%

Glucose Conjugation of Anthranilate by theArabidopsis UGT74F2 Glucosyltransferase Is Required for Tryptophan Mutant Blue Fluorescence

Quiel¹,

Bender

2003

Journal of Biological Chemistry

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Plant mutants with defects in intermediate enzymes of the tryptophan biosynthetic pathway often display a blue fluorescent phenotype. This phenotype results from the accumulation of the fluorescent tryptophan precursor anthranilate, the bulk of which is found in a glucose-conjugated form. To elucidate factors that control fluorescent tryptophan metabolites, we conducted a genetic screen for suppressors of blue fluorescence in the Arabidopsis trp1-100 mutant, which has a defect in the second enzymatic step of the tryptophan pathway. This screen yielded loss-of-function mutations in the UDP-glucosyltransferase gene UGT74F2. The bacterially expressed UGT74F2 enzyme catalyzed a conjugation reaction, with free anthranilate and UDP-glucose as substrates, that yielded the same fluorescent glucose ester compound as extracted from the trp1-100 mutant. These results indicate that sugar conjugation of anthranilate by UGT74F2 allows its stable accumulation in plant tissues. A highly related Arabidopsis enzyme UGT74F1 could also catalyze this reaction in vitro and could complement the ugt74F2 mutation when overexpressed in vivo. However, the UGT74F1 gene is expressed at a lower level than the UGT74F2 gene. Therefore, even though UGT74F1 and UGT74F2 have redundant conjugating activities toward anthranilate, UGT74F2 is the major source of this activity in the plant. The Arabidopsis genome encodes over 100 predicted UDPglucosyltransferase (UGT) 1 genes (1). These genes are identified by a conserved amino acid motif in the carboxyl-terminal region of the protein sequence that binds the common UDPglucose substrate molecule. UGT enzymes can form either glucose esters or glucosides with a wide range of substrate molecules. These enzymes serve a variety of important biological functions, including converting metabolically active molecules into inactive storage/transport forms or in some cases generating intermediates for the subsequent conversion into other metabolites. To understand the substrate specificity of the Arabidopsis UGTs, ninety of these enzymes have been expressed in bacteria and are being systematically tested for activity against a battery of potential substrate compounds. This strategy has identified specific Arabidopsis UGTs that can use the plant growth regulator indole-3-acetic acid (IAA) (2), various phenylpropanoid compounds (3), and various hydroxybenzoic acid compounds (4) as substrates in vitro. However, understanding the roles of specific UGTs in the plant is only in its early stages.The previous in vitro screening strategy identified the UGT74F1 and UGT74F2 enzymes as being able to use benzoic acid, 2-hydroxybenzoic acid (salicylic acid), and 3-hydroxybenzoic acid as substrates for glucose conjugation (4). Here we report that UGT74F1 and UGT74F2 can also use the tryptophan precursor compound 2-aminobenzoic acid (anthranilate) as a substrate for glucose ester conjugation both in vitro and in vivo. This finding has important implications for understanding the flux of metabolites in the tryptophan pathway.The ...

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A Phosphoribosylanthranilate Transferase Gene Is Defective in Blue Fluorescent Arabidopsis thaliana Tryptophan Mutants

Cited by 78 publications

References 34 publications

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

Mutation of a Rice Gene Encoding a Phenylalanine Biosynthetic Enzyme Results in Accumulation of Phenylalanine and Tryptophan

Glucose Conjugation of Anthranilate by theArabidopsis UGT74F2 Glucosyltransferase Is Required for Tryptophan Mutant Blue Fluorescence

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