Tripartite regulation of Gln3p by TOR, Ure2p, and phosphatases.
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.
Bertram
P G
PG
Department of Pathology and Immunology and the Molecular Genetics and Molecular Cell Biology Programs, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Choi
J H
JH
Carvalho
J
J
Ai
W
W
Zeng
C
C
Chan
T F
TF
Zheng
X F
XF
D004268:DNA-Binding Proteins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005979:Glutathione Peroxidase; D008957:Models, Genetic; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011328:Prions; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D020123:Sirolimus / Q000494:pharmacology; D016559:Tacrolimus / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D005979:Glutathione Peroxidase; D009687:Nuclear Proteins; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011328:Prions; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D020123:Sirolimus; D016559:Tacrolimus; D014157:Transcription Factors; C071664:GLN3 protein, S cerevisiae; C067020:URE2 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae