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GATA Factor Regulation in Excess Nitrogen Occurs Independently of Gtr-Ego Complex-Dependent TorC1 Activation.

Tate JJ, Georis I, Rai R, Vierendeels F, Dubois E, Cooper TG - G3 (Bethesda) (2015)

Bottom Line: To test this idea directly, we determined whether Gtr1/2- and Ego1/3-dependent TorC1 activation also was required for cytoplasmic Gln3 sequestration and repressed GATA factor-mediated transcription by abolishing the Gtr-Ego complex proteins.We show that Gln3 is sequestered in the cytoplasm of gtr1Δ, gtr2Δ, ego1Δ, and ego3Δ strains either long term in logarithmically glutamine-grown cells or short term after refeeding glutamine to nitrogen-limited or -starved cells; GATA factor-dependent transcription also was minimal.Our data demonstrate: (i) Gtr-Ego-dependent TorC1 activation is not required for cytoplasmic Gln3 sequestration in nitrogen-rich conditions; (ii) a novel Gtr-Ego-TorC1 activation-independent mechanism sequesters Gln3 in the cytoplasm; (iii) Gtr and Ego complex proteins participate in nuclear Gln3-Myc(13) localization, heretofore unrecognized functions for these proteins; and (iv) the importance of searching for new mechanisms associated with TorC1 activation and/or the regulation of Gln3 localization/function in response to changes in the cells' nitrogen environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163.

No MeSH data available.


Related in: MedlinePlus

Requirements of Gtr1 (B), Gtr2 (C), Ego1 (D), and Ego3 (E) for growth with repressive (glutamine) and derepressive (proline and allantoin) nitrogen sources. Wild-type (A) and mutant cells were streaked on the same plates containing YNB-glutamine, -proline or -allantoin medium. Cultures were incubated at 30° for 72 hr and photographed. Strain numbers and pertinent genotypes are indicated to the left of the images.
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fig1: Requirements of Gtr1 (B), Gtr2 (C), Ego1 (D), and Ego3 (E) for growth with repressive (glutamine) and derepressive (proline and allantoin) nitrogen sources. Wild-type (A) and mutant cells were streaked on the same plates containing YNB-glutamine, -proline or -allantoin medium. Cultures were incubated at 30° for 72 hr and photographed. Strain numbers and pertinent genotypes are indicated to the left of the images.

Mentions: To address the aforementioned questions, we deleted each of the four genes (GTR1, GTR2, EGO1, EGO3), verified that the production of the cognate mRNAs for each of them was abolished in the mutant cells (data not shown) and assayed their effects on growth in the presence of rich (glutamine) and poor (proline and allantoin) nitrogen sources (Figure 1). Three of the four mutant strains exhibited poor growth when proline or allantoin was provided as sole nitrogen source (Figure 1, A, C, D, and E). Growth of the gtr1Δ, however, did not slow to nearly the degree observed for the other three mutants with these nitrogen sources, but there was heterogeneity in the gtr1Δ colony sizes. Further, even with glutamine as sole nitrogen source, the growth of the ego1Δ and ego3Δ mutants was diminished relative to wild type (Figure 1, A, D, and E). In contrast, the growth of gtr2Δ mutant was only affected in the presence of poor nitrogen sources (Figure 1C).


GATA Factor Regulation in Excess Nitrogen Occurs Independently of Gtr-Ego Complex-Dependent TorC1 Activation.

Tate JJ, Georis I, Rai R, Vierendeels F, Dubois E, Cooper TG - G3 (Bethesda) (2015)

Requirements of Gtr1 (B), Gtr2 (C), Ego1 (D), and Ego3 (E) for growth with repressive (glutamine) and derepressive (proline and allantoin) nitrogen sources. Wild-type (A) and mutant cells were streaked on the same plates containing YNB-glutamine, -proline or -allantoin medium. Cultures were incubated at 30° for 72 hr and photographed. Strain numbers and pertinent genotypes are indicated to the left of the images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4528319&req=5

fig1: Requirements of Gtr1 (B), Gtr2 (C), Ego1 (D), and Ego3 (E) for growth with repressive (glutamine) and derepressive (proline and allantoin) nitrogen sources. Wild-type (A) and mutant cells were streaked on the same plates containing YNB-glutamine, -proline or -allantoin medium. Cultures were incubated at 30° for 72 hr and photographed. Strain numbers and pertinent genotypes are indicated to the left of the images.
Mentions: To address the aforementioned questions, we deleted each of the four genes (GTR1, GTR2, EGO1, EGO3), verified that the production of the cognate mRNAs for each of them was abolished in the mutant cells (data not shown) and assayed their effects on growth in the presence of rich (glutamine) and poor (proline and allantoin) nitrogen sources (Figure 1). Three of the four mutant strains exhibited poor growth when proline or allantoin was provided as sole nitrogen source (Figure 1, A, C, D, and E). Growth of the gtr1Δ, however, did not slow to nearly the degree observed for the other three mutants with these nitrogen sources, but there was heterogeneity in the gtr1Δ colony sizes. Further, even with glutamine as sole nitrogen source, the growth of the ego1Δ and ego3Δ mutants was diminished relative to wild type (Figure 1, A, D, and E). In contrast, the growth of gtr2Δ mutant was only affected in the presence of poor nitrogen sources (Figure 1C).

Bottom Line: To test this idea directly, we determined whether Gtr1/2- and Ego1/3-dependent TorC1 activation also was required for cytoplasmic Gln3 sequestration and repressed GATA factor-mediated transcription by abolishing the Gtr-Ego complex proteins.We show that Gln3 is sequestered in the cytoplasm of gtr1Δ, gtr2Δ, ego1Δ, and ego3Δ strains either long term in logarithmically glutamine-grown cells or short term after refeeding glutamine to nitrogen-limited or -starved cells; GATA factor-dependent transcription also was minimal.Our data demonstrate: (i) Gtr-Ego-dependent TorC1 activation is not required for cytoplasmic Gln3 sequestration in nitrogen-rich conditions; (ii) a novel Gtr-Ego-TorC1 activation-independent mechanism sequesters Gln3 in the cytoplasm; (iii) Gtr and Ego complex proteins participate in nuclear Gln3-Myc(13) localization, heretofore unrecognized functions for these proteins; and (iv) the importance of searching for new mechanisms associated with TorC1 activation and/or the regulation of Gln3 localization/function in response to changes in the cells' nitrogen environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163.

No MeSH data available.


Related in: MedlinePlus