Specific induction and carbon/nitrogen repression of arginine catabolism gene of Aspergillus nidulans—functional in vivo analysis of the otaA promoter

Dzikowska, Agnieszka; Kacprzak, Magdalena M.; Tomecki, Rafał; Koper, Michał; Scazzocchio, Claudio; Węgleński, Piotr

doi:10.1016/s1087-1845(02)00522-4

Cited by 27 publications

(27 citation statements)

References 53 publications

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“…Tian et al (17) suggested that an increase in Arg level in the IRM after the addition of NO 3 − to the ERM triggers the up-regulation of CAR1 and URE in the IRM of G. intraradices. Arg has been shown to induce the catabolic genes CAR1 and OAT in Aspergillus nidulans, and Arg catabolism is under the control of N metabolite repression and C catabolite repression systems (32). However, the constant transcript levels of CAR1 and URE, in combination with increased arginase and urease activity after the addition of sucrose to the RC, indicate that both genes are not only transcriptionally, but also posttranscriptionally and/or posttranslationally controlled in G. intraradices.…”

Section: Nhmentioning

confidence: 99%

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

Fellbaum

Gachomo

Beesetty

et al. 2012

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

338

250

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The arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and ubiquitous soil fungi of the phylum Glomeromycota, is responsible for massive nutrient transfer and global carbon sequestration. AM fungi take up nutrients from the soil and exchange them against photosynthetically fixed carbon (C) from the host. Recent studies have demonstrated that reciprocal reward strategies by plant and fungal partners guarantee a "fair trade" of phosphorus against C between partners [Kiers ET, et al. (2011) Science 333:880-882], but whether a similar reward mechanism also controls nitrogen (N) flux in the AM symbiosis is not known. Using mycorrhizal root organ cultures, we manipulated the C supply to the host and fungus and followed the uptake and transport of N sources in the AM symbiosis, the enzymatic activities of arginase and urease, and fungal gene expression in the extraradical and intraradical mycelium. We found that the C supply of the host plant triggers the uptake and transport of N in the symbiosis, and that the increase in N transport is orchestrated by changes in fungal gene expression. N transport in the symbiosis is stimulated only when the C is delivered by the host across the mycorrhizal interface, not when C is supplied directly to the fungal extraradical mycelium in the form of acetate. These findings support the importance of C flux from the root to the fungus as a key trigger for N uptake and transport and provide insight into the N transport regulation in the AM symbiosis.arbuscular mycorrhiza | arginine catabolism | carbon transport | Glomus intraradices | urea cycle T he arbuscular mycorrhizal (AM) symbiosis plays a key role in nutrient uptake in the majority of land plants, including such important crop species as corn, soybean, and rice. The AM symbiosis can increase the uptake of phosphate (P) and nitrogen (N), as well as of trace elements such as copper and zinc, and improves the abiotic and biotic stress resistance of the host (2). Previous work has focused primarily on the transport of P in AM symbiosis, but more recent work has highlighted the potential importance of N uptake by fungal symbionts (3, 4). The extraradical mycelium (ERM) of the fungus is able to take up NH 4 + (5, 6), NO 3 − (5-7), and organic N resources (3-5) from the soil and to transfer N to the host. The high mobility of N in the soil has raised the question of whether AM fungi can contribute significantly to the N nutrition of the host (8). It has been suggested that an improved N status of mycorrhizal plants may be simply a consequence of an improved P nutrition (9); however, other studies have demonstrated that AM fungi can deliver substantial amounts of N to the host, with an estimated 21% of total N taken up by the fungal ERM in root organ cultures (10) and 74% of the total N in the leaves of Zea mays coming from the fungal ERM with access to urea (11).Current models of N transport in the AM symbiosis involve uptake of inorganic N from the soil and N assimilation via the anabolic arm of the urea...

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Section: Nhmentioning

confidence: 99%

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

Fellbaum

Gachomo

Beesetty

et al. 2012

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

338

250

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“…Ornithine aminotransferase (GiOAT; EC 2.6.1.13) and ornithine decarboxylase (GiODC; EC 4.1.1.17) are two enzymes that catalyze the breakdown of Orn (Borsuk et al, 1999;Dzikowska et al, 2003;Wagemaker et al, 2005). OAT catalyzes the transamination of a-ketoglutarate with Orn or N-acetylornithine and of Glu-5-semialdehyde with Glu and Ala. GiOAT1 has a deduced 442-amino acid sequence with a predicted molecular mass of 49 kD and an aminotransferase class III pyridoxal-phosphate attachment site (LIA-DEVLTGLARTGKLLCQEHDEVRADIVILGKALSGG) and differs from a partial sequence reported recently for a putative GiOAT2 (Gomez et al, 2009; Table I; Supplemental Fig.…”

Section: Enzymes Involved In Arg Breakdownmentioning

confidence: 99%

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

et al. 2010

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The arbuscular mycorrhiza (AM) brings together the roots of over 80% of land plant species and fungi of the phylum Glomeromycota and greatly benefits plants through improved uptake of mineral nutrients. AM fungi can take up both nitrate and ammonium from the soil and transfer nitrogen (N) to host roots in nutritionally substantial quantities. The current model of N handling in the AM symbiosis includes the synthesis of arginine in the extraradical mycelium and the transfer of arginine to the intraradical mycelium, where it is broken down to release N for transfer to the host plant. To understand the mechanisms and regulation of N transfer from the fungus to the plant, 11 fungal genes putatively involved in the pathway were identified from Glomus intraradices, and for six of them the full-length coding sequence was functionally characterized by yeast complementation. Two glutamine synthetase isoforms were found to have different substrate affinities and expression patterns, suggesting different roles in N assimilation. The spatial and temporal expression of plant and fungal N metabolism genes were followed after nitrate was added to the extraradical mycelium under N-limited growth conditions using hairy root cultures. In parallel experiments with 15 N, the levels and labeling of free amino acids were measured to follow transport and metabolism. The gene expression pattern and profiling of metabolites involved in the N pathway support the idea that the rapid uptake, translocation, and transfer of N by the fungus successively trigger metabolic gene expression responses in the extraradical mycelium, intraradical mycelium, and host plant.

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“…Previous attempts to inactivate areB were unsuccessful and the implication that AreB has a role in nitrogen regulation in A. nidulans came from analysis of areB translocation mutants (Conlon et al, 2001;Dzikowska et al, 2003). Since these initial studies, A. nidulans nkuAD gene targeting strains have been constructed to facilitate homologous integration (Nayak et al, 2006).…”

Section: A Single Areb Orthologue Is Present In Filamentous Fungimentioning

confidence: 99%

“…Putative areB null mutations resulting in premature truncation of AreBcryptic-activation-domain fusions were isolated by selection for loss of this suppression (Conlon et al 2001). These mutants showed derepression of ornithine transaminase under certain carbon limitation conditions (Dzikowska et al, 2003). Although these mutants are likely loss-offunction mutants, attempts to generate areB deletion strains were unsuccessful (Conlon et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Deletion and overexpression of the Aspergillus nidulans GATA factor AreB reveals unexpected pleiotropy

et al. 2009

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The Aspergillus nidulans transcription factor AreA is a key regulator of nitrogen metabolic gene expression. AreA contains a C-terminal GATA zinc finger DNA-binding domain and activates expression of genes necessary for nitrogen acquisition. Previous studies identified AreB as a potential negative regulator of nitrogen catabolism showing similarity with Penicillium chrysogenum NreB and Neurospora crassa ASD4. The areB gene encodes multiple products containing an N-terminal GATA zinc finger and a leucine zipper motif. We deleted the areB gene and now show that AreB negatively regulates AreA-dependent nitrogen catabolic gene expression under nitrogen-limiting or nitrogen-starvation conditions. AreB also acts pleiotropically, with functions in growth, conidial germination and asexual development, though not in sexual development. AreB overexpression results in severe growth inhibition, aberrant cell morphology and reduced AreA-dependent gene expression. Deletion of either the DNA-binding domain or the leucine zipper domain results in loss of both nitrogen and developmental phenotypes.

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Specific induction and carbon/nitrogen repression of arginine catabolism gene of Aspergillus nidulans—functional in vivo analysis of the otaA promoter

Cited by 27 publications

References 53 publications

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

Regulation of the Nitrogen Transfer Pathway in the Arbuscular Mycorrhizal Symbiosis: Gene Characterization and the Coordination of Expression with Nitrogen Flux

Deletion and overexpression of the Aspergillus nidulans GATA factor AreB reveals unexpected pleiotropy

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