Abstract
Gln3p is a GATA-type transcription factor responsive to different nitrogen nutrients and starvation in yeast Saccharomyces cerevisiae. Recent evidence has linked TOR signaling to Gln3p. Rapamycin causes dephosphorylation and nuclear translocation of Gln3p, thereby activating nitrogen catabolite repressible-sensitive genes. However, a detailed mechanistic understanding of this process is lacking. In this study, we show that Tor1p physically interacts with Gln3p. An intact TOR kinase domain is essential for the phosphorylation of Gln3p, inhibition of Gln3p nuclear entry and repression of Gln3p-dependent transcription. In contrast, at least two distinct protein phosphatases, Pph3p and the Tap42p-dependent phosphatases, are involved in the activation of Gln3p. The yeast pro-prion protein Ure2p binds to both hyper- and hypo-phosphorylated Gln3p. In contrast to the free Gln3p, the Ure2p-bound Gln3p is signifcantly resistant to dephosphorylation. Taken together, these results reveal a tripartite regulatory mechanism by which the phosphorylation of Gln3p is regulated.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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DNA-Binding Proteins / metabolism*
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Fluorescent Antibody Technique
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Fungal Proteins / chemistry
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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Gene Expression Regulation, Fungal / drug effects
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Glutathione Peroxidase
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Models, Genetic
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Mutation
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Nuclear Proteins / metabolism
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Phosphatidylinositol 3-Kinases*
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Phosphoric Monoester Hydrolases / genetics
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Phosphoric Monoester Hydrolases / metabolism*
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Phosphorylation
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Phosphotransferases (Alcohol Group Acceptor) / chemistry
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Phosphotransferases (Alcohol Group Acceptor) / genetics
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Phosphotransferases (Alcohol Group Acceptor) / metabolism*
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Prions*
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Protein Binding
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Protein Structure, Tertiary
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Protein Transport / drug effects
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Recombinant Fusion Proteins
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Repressor Proteins / metabolism
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Sirolimus / pharmacology
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Tacrolimus / pharmacology
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Transcription Factors / metabolism
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Two-Hybrid System Techniques
Substances
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DNA-Binding Proteins
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Fungal Proteins
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GLN3 protein, S cerevisiae
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Nuclear Proteins
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Prions
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RNA, Messenger
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Recombinant Fusion Proteins
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Glutathione Peroxidase
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URE2 protein, S cerevisiae
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Phosphotransferases (Alcohol Group Acceptor)
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TOR1 protein, S cerevisiae
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Phosphoric Monoester Hydrolases
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Sirolimus
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Tacrolimus