Two Anthranilate Synthase Genes in Arabidopsis: Defense-Related Regulation of the Tryptophan Pathway

Niyogi, Krishna; Fink, Gerald R.

doi:10.2307/3869530

Cited by 38 publications

(52 citation statements)

References 51 publications

(69 reference statements)

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“…Interestingly, DHS2 of tomato is also the gene which responds to elicitors. This genetic combination of both a constitutively expressed and a regulated gene coding for isoforms of one enzyme parallels the situation for the anthranilate synthase (AS; EC 4.1.3.27) a-subunit genes in Arabidopsis (27). AS is the first enzyme of that branch of the shikimate pathway which leads to tryptophan and also to the indole phytoalexins of the Cruciferae (28).…”

Section: Resultsmentioning

confidence: 86%

“…AS is the first enzyme of that branch of the shikimate pathway which leads to tryptophan and also to the indole phytoalexins of the Cruciferae (28). One of the two genes (ASAl) encoding an a-subunit of AS is regulated in an organ-specific manner and is also wound and elicitor inducible, while the other gene (ASA2) is constitutively expressed (27). Besides DAHP synthase and AS, CS is the third enzyme of the shikimate pathway known to be encoded by two distinct genes which respond differentially to pathogen-derived stress factors.…”

Section: Resultsmentioning

confidence: 99%

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Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Görlach

Raesecke

Rentsch

et al. 1995

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

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The accumulation of phenylalanine-derived phenolic compounds is a well-known element of a plant's defense in response to pathogen attack Phenylalanine, as well as the other two aromatic amino acids, tyrosine and tryptophan, is synthesized by way of the shikimate pathway. The first seven steps of the shikimate pathway (the prechorismate pathway) are common for the biosynthesis of all three aromatic amino acids. We have studied transcript levels of six genes-i.e., two 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase genes, one shikimate kinase gene, one 5-enolpyruvylshikimate 3-phosphate synthase gene, and two chorismate synthase genes-corresponding to four steps of the prechorismate pathway, in cultured tomato cells exposed to fungal elicitors.

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Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Görlach

Raesecke

Rentsch

et al. 1995

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

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“…1). For example, AtICS1 and AtASA1 are induced in response to bacterial pathogens (17,39) and defense-related products of these pathways, camalexin (via anthranilate) and SA (via IC), are detected in parallel.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsis Isochorismate Synthase Functional in Pathogen-induced Salicylate Biosynthesis Exhibits Properties Consistent with a Role in Diverse Stress Responses

Strawn

Marr

Inoue

et al. 2007

Journal of Biological Chemistry

217

146

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Salicylic acid (SA) is a phytohormone best known for its role in plant defense. It is synthesized in response to diverse pathogens and responsible for the large scale transcriptional induction of defense-related genes and the establishment of systemic acquired resistance. Surprisingly, given its importance in plant defense, an understanding of the underlying enzymology is lacking. In Arabidopsis thaliana, the pathogen-induced accumulation of SA requires isochorismate synthase (AtICS1). Here, we show that AtICS1 is a plastid-localized, stromal protein using chloroplast import assays and immunolocalization. AtICS1 acts as a monofunctional isochorismate synthase (ICS), catalyzing the conversion of chorismate to isochorismate (IC) in a reaction that operates near equilibrium (K eq ‫؍‬ 0.89). It does not convert chorismate directly to SA (via an IC intermediate) as does Yersinia enterocolitica Irp9. Using an irreversible coupled spectrophotometric assay, we found that AtICS1 exhibits an apparent K m of 41.5 M and k cat ‫؍‬ 38.7 min ؊1 for chorismate. This affinity for chorismate would allow it to successfully compete with other pathogen-induced, chorismate-utilizing enzymes. Furthermore, the biochemical properties of AtICS1 indicate its activity is not regulated by light-dependent changes in stromal pH, Mg 2؉ , or redox and that it is remarkably active at 4°C consistent with a role for SA in cold-tolerant growth. Finally, our analyses support plastidic synthesis of stress-induced SA with the requirement for one or more additional enzymes responsible for the conversion of IC to SA, because non-enzymatic conversion of IC to SA under physiological conditions was negligible.

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“…There are several examples of duplication of tryptophan pathway genes (39)(40)(41)(42) with substantial evidence that one acts in tryptophan production while the other affords intermediates for production of defensive secondary metabolites (43)(44)(45). In Ruta graveolens, one of the duplicate genes for anthranilate synthase alpha (AS␣2) is constitutive and the corresponding enzyme is feedback-inhibited by L-tryptophan.…”

Section: Discussionmentioning

confidence: 99%

A deletion in an indole synthase gene is responsible for the DIMBOA-deficient phenotype ofbxbx maize

Melanson

Chilton

Masters-Moore

et al. 1997

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

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The biosynthesis of DIMBOA, a pesticidal secondary metabolite of maize, branches off the tryptophan pathway. We have previously demonstrated that indole is the last intermediate common to both the tryptophan and hydroxamic acid pathways. The earliest discovered mutant in the DIMBOA pathway, bxbx (benzoxazineless), is deficient in the production of DIMBOA and related compounds. This paper presents evidence We demonstrate that the TSA gene has sustained a 924-bp deletion in bxbx compared with its counterpart in wild-type maize. We report that the TSA gene maps to the same location as the bxbx mutation, on the short arm of chromosome 4. We present evidence that the very early and very high level of expression of TSA corresponds to the timing and level of DIMBOA biosynthesis but is strikingly different from the expression of the maize tryptophan synthase ␤ (TSB) genes. We show that feeding indole to bxbx seedlings restores their ability to synthesize DIMBOA. We conclude that the maize enzyme initially named tryptophan synthase ␣ in fact is a DIMBOA biosynthetic enzyme, and we propose that it be renamed indole synthase. This work confirms and enlarges upon the findings of Frey et al.

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Two Anthranilate Synthase Genes in Arabidopsis: Defense-Related Regulation of the Tryptophan Pathway

Cited by 38 publications

References 51 publications

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Temporally distinct accumulation of transcripts encoding enzymes of the prechorismate pathway in elicitor-treated, cultured tomato cells.

Arabidopsis Isochorismate Synthase Functional in Pathogen-induced Salicylate Biosynthesis Exhibits Properties Consistent with a Role in Diverse Stress Responses

A deletion in an indole synthase gene is responsible for the DIMBOA-deficient phenotype ofbxbx maize

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