The gene encoding the major proline transporter of <i>Aspergillus nidulans </i>is upregulated during conidiospore germination and in response to proline induction and amino acid starvation

Tazebay, Uygar Halis; Sophianopoulou, Vicky; Scazzocchio, Claudio; Diallinas, George

doi:10.1046/j.1365-2958.1997.3201689.x

Cited by 50 publications

(73 citation statements)

References 45 publications

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“…The transcription of prnB (but not of prnD) can be elicited independently from proline induction by amino acid starvation, possibly mediated by a GCN4-like factor (56). This activation is lower, but noticeable, in a strain with prnA deleted (56). We used 3-amino-1,2,4-triazole, a competitive inhibitor of the histidine biosynthetic enzyme His3p, to induce amino acid starvation (as in reference 56).…”

Section: Resultsmentioning

confidence: 99%

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Chromatin Rearrangements in the prnD-prnB Bidirectional Promoter: Dependence on Transcription Factors

García¹,

González²,

Gómez³

et al. 2004

Eukaryot Cell

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The prnD-prnB intergenic region regulates the divergent transcription of the genes encoding proline oxidase and the major proline transporter. Eight nucleosomes are positioned in this region. Upon induction, the positioning of these nucleosomes is lost. This process depends on the specific transcriptional activator PrnA but not on the general GATA factor AreA. Induction of prnB but not prnD can be elicited by amino acid starvation. A specific nucleosomal pattern in the prnB proximal region is associated with this process. Under conditions of induction by proline, metabolite repression depends on the presence of both repressing carbon (glucose) and nitrogen (ammonium) sources. Under these repressing conditions, partial nucleosomal positioning is observed. This depends on the CreA repressor's binding to two specific cis-acting sites. Three conditions (induction by the defective PrnA80 protein, induction by amino acid starvation, and induction in the presence of an activated CreA) result in similar low transcriptional activation. Each results in a different nucleosome pattern, which argues strongly for a specific effect of each signal on nucleosome positioning. Experiments with trichostatin A suggest that both default nucleosome positioning and partial positioning under induced-repressed conditions depend on deacetylated histones.In simple eukaryotes, some genes are transcribed divergently from a common bidirectional promoter. Well-studied examples are the GAL1-GAL10 promoter of Saccharomyces cerevisioe (reviewed in references 10 and 35) and the niiA-niaD promoter of Aspergillus nidulans (37, 41, 52). Here we analyzed the nucleosome rearrangements of the bidirectional prnD-prnB intergenic region. This is a 1.7-kb region located between the gene coding for proline oxidase (prnD) and the one coding for the major, specific proline transporter (prnB) (29, 50). These genes are located in the prn gene cluster in the right arm of chromosome VII (Fig. 1). The regulation of prnD and prnB involves a multiplicity of metabolic signals. The pathway-specific transcription factor PrnA is essential for proline induction of both genes (11,21,22,46). The prnD-prnB intergenic region is a genuine bidirectional promoter, as mutations in the two PrnA binding sites present in this region affect the transcription of both prnD and prnB (21; I. García, D. Gómez, and C. Scazzocchio, unpublished results).Transcription of prnB but not of prnD can also be induced by amino acid starvation. This effect depends on the integrity of a canonical GCN4 binding site in the proximity of the prnB TATA box (56).Repression of both prnB and prnD occurs only when both carbon (glucose) and nitrogen-repressing (ammonium) sources are present simultaneously (2, 5, 6, 21, 22). Repression acts directly on prnB expression, while repression of prnD is indirect and results from inducer exclusion (5, 16, 22). Repression necessitates both the activation of the negative regulator CreA and the inactivation of the GATA factor AreA. A model to account for this pattern of re...

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Section: Resultsmentioning

confidence: 99%

“…This effect depends on the integrity of a canonical GCN4 binding site in the proximity of the prnB TATA box (56).…”

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Chromatin Rearrangements in the prnD-prnB Bidirectional Promoter: Dependence on Transcription Factors

García¹,

González²,

Gómez³

et al. 2004

Eukaryot Cell

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“…A number of transporter genes, including the A. nidulans proline-specific transporter gene prnB (57), are expressed during conidial isotropic growth. This expression, which is independent from the regulatory circuits operating in mycelia (1,64), lasts for about 4 h after conidial germination in liquid MM at 37°C (1). Figure 7 shows that agtA is transcribed at relatively high levels at the 2-h time point after induction of germination (corresponding to the isotropic growth phase), where transcript levels are very similar on glutamate and urea, but transcription is progressively switched off when urea is the nitrogen source, attaining relatively low levels at the 8-h time point, where a majority of germinating spores have established polarity and given rise to germlings.…”

Section: Vol 8 2009 a Nidulans Dicarboxylic Amino Acid Transportermentioning

confidence: 99%

AgtA, the Dicarboxylic Amino Acid Transporter of Aspergillus nidulans , Is Concertedly Down-Regulated by Exquisite Sensitivity to Nitrogen Metabolite Repression and Ammonium-Elicited Endocytosis

et al. 2009

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We identified agtA, a gene that encodes the specific dicarboxylic amino acid transporter of Aspergillus nidulans. The deletion of the gene resulted in loss of utilization of aspartate as a nitrogen source and of aspartate uptake, while not completely abolishing glutamate utilization. Kinetic constants showed that AgtA is a high-affinity dicarboxylic amino acid transporter and are in agreement with those determined for a cognate transporter activity identified previously. The gene is extremely sensitive to nitrogen metabolite repression, depends on AreA for its expression, and is seemingly independent from specific induction. We showed that the localization of AgtA in the plasma membrane necessitates the ShrA protein and that an active process elicited by ammonium results in internalization and targeting of AgtA to the vacuole, followed by degradation. Thus, nitrogen metabolite repression and ammonium-promoted vacuolar degradation act in concert to downregulate dicarboxylic amino acid transport activity.Amino acids can be utilized by saprophytic fungi as nitrogen and/or carbon sources. Their uptake is mediated by transmembrane proteins belonging to the specific fungal YAT (TC 2.A.3.10, yeast amino acid transporter) family, a member of the APC (amino acid polyamine choline) superfamily (25), which shows a wide range of substrate specificities and includes representatives in all realms of life (53). In Saccharomyces cerevisiae (51), 18 YAT transporters have been functionally characterized, while only a few have been studied in other organisms (8,25,35,57,67,68,69,72,76; Saccharomyces genome database at http://www.yeastgenome.org/). The YAT family transporters share a common predicted topology, comprising 12 transmembrane domains, and show, even among proteins with completely different substrate specificities, a high degree of sequence identity (2, 25). The transporters of the dicarboxylic amino acids glutamate and aspartate have been characterized in S. cerevisiae (DIP5; 47) and Penicillium chrysogenum (PcDIP5; 68) and are members of this family. In A. nidulans, specific dicarboxylic amino acid transport activity and certain aspects of its regulation were previously reported (24, 26, 42, 51, 52), but the corresponding gene(s) was not characterized.In fungi, the genes that encode transporters and enzyme activities involved in nitrogen source utilization are subject to tight transcriptional and/or posttranscriptional controls. Preferred nitrogen sources (such as ammonium and glutamine) repress the transcription of genes involved in the utilization of metabolically less favorable nitrogen sources such as nitrate, purines, or amino acids. In A. nidulans, nitrogen metabolite repression acts by inactivating the AreA GATA transcriptional activator (30) by a number of concurring mechanisms (36, 66). In S. cerevisiae, a transcriptional repression mechanism similar but not identical to the one described above for A. nidulans is operative (see reference 33 for a review).In addition to being subject to transcriptional regulati...

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“…Characterized members include 15 of the 16 characterized amino acid transporters of Saccharomyces cerevisiae (5,6), two proteins of Aspergillus nidulans, PrnB and AgtA (7,8), as well as transporters from Candida glabrata, Neurospora crassa, and Penicillium chrysogenum (9 -11). These proteins display different specificities and are subject to tight transcriptional and post-translational regulation (12)(13)(14).…”

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The Aspergillus nidulans Proline Permease as a Model for Understanding the Factors Determining Substrate Binding and Specificity of Fungal Amino Acid Transporters

Gournas

Evangelidis

Αθανασόπουλος

et al. 2015

Journal of Biological Chemistry

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Background: PrnB, different from Put4p, its Saccharomyces cerevisiae orthologue, is a highly specific L-proline transporter of Aspergillus nidulans. Results: Identification of 12 residues important for PrnB activity and/or specificity. Put4p-mimicking mutants of PrnB recognize other Put4p substrates. Conclusion: Residues variable in the yeast amino acid transporter (YAT) family determine transporter specificity. Significance: Understanding the molecular mechanisms underlying amino acid recognition and translocation through YATs.

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The gene encoding the major proline transporter of Aspergillus nidulans is upregulated during conidiospore germination and in response to proline induction and amino acid starvation

Cited by 50 publications

References 45 publications

Chromatin Rearrangements in the prnD-prnB Bidirectional Promoter: Dependence on Transcription Factors

Chromatin Rearrangements in the prnD-prnB Bidirectional Promoter: Dependence on Transcription Factors

AgtA, the Dicarboxylic Amino Acid Transporter of Aspergillus nidulans , Is Concertedly Down-Regulated by Exquisite Sensitivity to Nitrogen Metabolite Repression and Ammonium-Elicited Endocytosis

The Aspergillus nidulans Proline Permease as a Model for Understanding the Factors Determining Substrate Binding and Specificity of Fungal Amino Acid Transporters

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