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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

Time course of Gln3-Myc13 localization in gtr1Δ (FV406) cells after nitrogen starvation (A and B), transfer from nitrogen-replete to nitrogen-limiting medium (C and D), and resupplying excess nitrogen to all of the cultures (A−D). The experimental format and treatment of the samples were identical to those in Figure 2.
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fig3: Time course of Gln3-Myc13 localization in gtr1Δ (FV406) cells after nitrogen starvation (A and B), transfer from nitrogen-replete to nitrogen-limiting medium (C and D), and resupplying excess nitrogen to all of the cultures (A−D). The experimental format and treatment of the samples were identical to those in Figure 2.

Mentions: The first mutant analyzed was a gtr1Δ (FV406). Consistent with the growth data (Figure 1), there was no demonstrable effect of deleting GTR1 other than a small shift in the kinetics of Gln3-Myc13 movement from the cytoplasm to the nucleus during short-term nitrogen limitation or long-term nitrogen starvation (Figure 3, A and B). Otherwise, the gtr1Δ exhibited a wild-type phenotype (Figure 2vs.Figure 3, A and B). We also were unable to demonstrate a significant change in the behavior of Gln3-Myc13 localization for up to 5 hr after transferring gtr1Δ cells from a rich to a poor nitrogen source (Figure 3, C and D). Some Gln3-Myc13 movement out of the nucleus did occur, however, between the 5th and 6th hours after the transfer to proline medium; the significance of this observation is unclear.


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)

Time course of Gln3-Myc13 localization in gtr1Δ (FV406) cells after nitrogen starvation (A and B), transfer from nitrogen-replete to nitrogen-limiting medium (C and D), and resupplying excess nitrogen to all of the cultures (A−D). The experimental format and treatment of the samples were identical to those in Figure 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Time course of Gln3-Myc13 localization in gtr1Δ (FV406) cells after nitrogen starvation (A and B), transfer from nitrogen-replete to nitrogen-limiting medium (C and D), and resupplying excess nitrogen to all of the cultures (A−D). The experimental format and treatment of the samples were identical to those in Figure 2.
Mentions: The first mutant analyzed was a gtr1Δ (FV406). Consistent with the growth data (Figure 1), there was no demonstrable effect of deleting GTR1 other than a small shift in the kinetics of Gln3-Myc13 movement from the cytoplasm to the nucleus during short-term nitrogen limitation or long-term nitrogen starvation (Figure 3, A and B). Otherwise, the gtr1Δ exhibited a wild-type phenotype (Figure 2vs.Figure 3, A and B). We also were unable to demonstrate a significant change in the behavior of Gln3-Myc13 localization for up to 5 hr after transferring gtr1Δ cells from a rich to a poor nitrogen source (Figure 3, C and D). Some Gln3-Myc13 movement out of the nucleus did occur, however, between the 5th and 6th hours after the transfer to proline medium; the significance of this observation is unclear.

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