In yeast target of rapamycin complex 1 (TORC1) and Tap42-associated phosphatases regulate expression of genes involved in nitrogen limitation response and the nitrogen discrimination pathway. However, it remains unclear whether TORC1 and the phosphatases are required for sensing nitrogen conditions. Utilizing temperature sensitive mutants of tor2 and tap42, we examined the role of TORC1 and Tap42 in nuclear entry of Gln3, a key transcription factor in yeast nitrogen metabolism, in response to changes in nitrogen conditions. Our data show that TORC1 is essential for Gln3 nuclear entry upon nitrogen limitation and downshift in nitrogen quality. However, Tap42-associated phosphatases are required only under nitrogen limitation condition. In cells grown in poor nitrogen medium, the nitrogen permease reactivator kinase (Npr1) inhibits TORC1 activity and alters its association with Tap42, rendering Tap42-associated phosphatases unresponsive to nitrogen limitation. These findings demonstrate a direct role for TORC1 and Tap42-associated phosphatases in sensing nitrogen conditions and unveil an Npr1-dependent mechanism that controls TORC1 and the phosphatases in response to changes in nitrogen quality.
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http://dx.doi.org/10.1111/mmi.13858 | DOI Listing |
Mol Microbiol
December 2017
Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
In yeast target of rapamycin complex 1 (TORC1) and Tap42-associated phosphatases regulate expression of genes involved in nitrogen limitation response and the nitrogen discrimination pathway. However, it remains unclear whether TORC1 and the phosphatases are required for sensing nitrogen conditions. Utilizing temperature sensitive mutants of tor2 and tap42, we examined the role of TORC1 and Tap42 in nuclear entry of Gln3, a key transcription factor in yeast nitrogen metabolism, in response to changes in nitrogen conditions.
View Article and Find Full Text PDFAutophagy
July 2009
Life Sciences Institute, Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-2216, USA.
Autophagy is a highly conserved degradative process in eukaryotic cells. This process plays an integral role in cellular physiology, and the levels of autophagy must be precisely controlled to prevent cellular dysfunction. The rapamycin-sensitive Tor kinase complex 1 (TORC1) has a major role in regulating the induction of autophagy; however, the regulatory mechanisms are not fully understood.
View Article and Find Full Text PDFYeast
October 2008
Department of Cell Biology and Genetics, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
We previously reported that overproduction of non-translatable mRNA silences Ty1 transcription, possibly via functional inactivation of the nuclear cap-binding complex (CBC) and subsequent hyperstimulation of the TORC1 pathway. Further experimental evidence for CBC-to-TORC1 signalling in Ty1 transcriptional silencing is presented here. The role of Tap42 (a key downstream component of the TORC1 pathway) was tested.
View Article and Find Full Text PDFCell Cycle
December 2006
Aureon Laboratories, Inc, Yonkers, New York, USA.
In the budding yeast Saccharomyces cerevisiae, rapamycin has been known to induce a rapid dephosphorylation of many downstream targets of Tor. The key components mediating this dephosphorylation process are the Tap42-associated phosphatases, which become active upon rapamycin treatment. However, the mechanism by which rapamycin rapidly activates phosphatases is unclear.
View Article and Find Full Text PDFEMBO J
August 2006
Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
In Saccharomyces cerevisiae, the Tap42-phosphatase complexes are major targets of the Tor kinases in the rapamycin-sensitive signaling pathway. The immunosuppressive agent, rapamycin, induces a prompt activation of the Tap42-associated phosphatases, which is vitally important in Tor-mediated transcriptional regulation. However, the mechanism for the rapid phosphatase activation is poorly understood.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!