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The Gln3 Response To Nitrogen‐Rich Environments Is Independent of Vam6‐, Gtr1/2‐, Ego1/3‐Dependent TorC1 Activation
Author(s) -
Cooper Terrance,
Tate Jennifer,
Georis Isabelle,
Rai Rajendra,
Vierendeels Fabienne,
Dubois Evelyne
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.880.18
Subject(s) - transcription factor , glutamine , intracellular , cytoplasm , gata transcription factor , transcription (linguistics) , microbiology and biotechnology , activator (genetics) , nitrogen , chemistry , biochemistry , biology , promoter , amino acid , gene expression , gene , linguistics , philosophy , organic chemistry
Vam6, Gtr1/2, and Ego1/3 are required for leucine‐dependent TorC1 kinase activation which is central to nitrogen‐responsive regulation. However, Gln3, a nitrogen‐responsive transcription activator, does not respond to leucine‐dependent TorC1 activation. In nitrogen excess, Gln3 is cytoplasmic and Gln3‐mediated transcription minimal, whereas in nitrogen limitation, starvation, or following rapamycin treatment, Gln3 is nuclear and transcription greatly increased. Increasing evidence demonstrates nitrogen‐responsive intracellular Gln3 localization is subject to multiple modes of regulation. To ascertain whether the Vam6, Gtr‐Ego complexes participate in the regulation of Gln3, we determined the requirements of the above proteins for nuclear localization and cytoplasmic sequestration of Gln3 in response to nitrogen excess, starvation or limitation. We show that Gln3 is sequestered in the cytoplasm of vam6Δ , gtr1Δ , gtr2Δ , ego1Δ and ego3Δ either long‐term in logarithmically glutamine‐grown cells or short‐term after re‐feeding glutamine to nitrogen‐limited or ‐starved cells; GATA factor‐dependent transcription was also minimal. However, in all of the deletion mutants except gtr1Δ , nuclear Gln3 localization elicited by nitrogen limitation or starvation is adversely affected. These data indicate that a Vam6‐, Gtr1/2‐, Ego1/3‐independent, nitrogen‐responsive mechanism exists to sequester Gln3 in the cytoplasm and suggests the above proteins possess additional functions beyond those associated with TorC1 activation. Support NIH GM‐35642, COCOF and FRFC 2.4547.11.