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The Ure2 αCap Is Required for GATA Factor Responses to Rapamycin, But Not Nitrogen Limitation
Author(s) -
Tate Jennifer J.,
Feller Andre,
Georis Isabelle,
Dubois Evelyne,
Cooper Terrance G.
Publication year - 2013
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.27.1_supplement.980.9
Subject(s) - regulator , gata transcription factor , transcription factor , dephosphorylation , microbiology and biotechnology , biology , chemistry , phosphorylation , genetics , phosphatase , gene , promoter , gene expression
Ure2 is a phosphoprotein and central negative regulator of nitrogen‐responsive Gln3 and Gat1 localization and their abilities to activate transcription. This negative regulation is achieved by forming Ure2‐Gln3 and Ure2‐Gat1 complexes which sequester these GATA factors in the cytoplasm of cells cultured in excess nitrogen. Ure2 itself is a dimer, the monomer of which consists of two core domains and a flexible protruding αcap. Here, we show that alterations in this αcap abolish rapamycin‐ (Rap‐) elicited nuclear Gln3 and, to a more limited extent, Gat1 localization but have little effect on the Gln3 and Gat1 responses to nitrogen limitation. Rap is a specific inhibitor of the global regulator, TorC1. Ure2 dephosphorylation is also stimulus‐specific, occurring after Rap treatment, but only minimally if at all in nitrogen‐limited cells. In contrast to Gln3, Rap‐elicited Ure2 dephosphorylation is independent of Sit4 and PP2A. Our data suggest that distinct regions of Ure2 are associated with the receipt and/or implementation of signals calling for cessation of GATA factor sequestration in the cytoplasm. This in turn is more consistent with the existence of distinct pathways for TorC1‐ and nitrogen limitation‐dependent control of GATA factor localization and function than it is with these stimuli representing sequential steps in a single regulatory pathway. Supported by: NIH GM‐35642–23, COCOF, FRFC 2.4547.11.