The 14-3-3 proteins positively regulate rapamycin-sensitive signaling.
BACKGROUND
The kinase Tor is the target of the immunosuppressive drug rapamycin and is a member of the phosphatidylinositol kinase (PIK)-related kinase family. It plays an essential role in progression through the G1 phase of the cell cycle. The molecular details of Tor signaling remain obscure, however.


RESULTS
We isolated two Saccharomyces cerevisiae genes, BMH1 and BMH2, as multicopy suppressors of the growth-inhibitory phenotype caused by rapamycin in budding yeast. BMH1 and BMH2 encode homologs of the 14-3-3 signal transduction proteins. Deletion of one or both BMH genes caused hypersensitivity to rapamycin in a manner that was dependent on gene dosage. In addition, alterations in the phosphopeptide-binding pocket of the 14-3-3 proteins had dramatically different effects on their ability to relieve the growth-arresting rapamycin phenotype. Mutations that prevented 14-3-3 from binding to a phosphoserine motif abolished its ability to confer rapamycin resistance. In contrast, substitution of two residues in 14-3-3 that surround these phosphoserine-binding sites conferred a dominant rapamycin-resistant phenotype.


CONCLUSIONS
Our studies reveal 14-3-3 as an important component in rapamycin-sensitive signaling and provide significant new insights into the structure and function of 14-3-3 proteins.
Bertram
P G
PG
Department of Pathology Washington University School of Medicine St. Louis, Missouri, 63110, USA.
Zeng
C
C
Thorson
J
J
Shaw
A S
AS
Zheng
X F
XF
D048948:14-3-3 Proteins; D001665:Binding Sites; D004352:Drug Resistance, Microbial; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005800:Genes, Fungal; D006801:Humans; D020104:Immunophilins / Q000378:metabolism; D008024:Ligands; D019869:Phosphatidylinositol 3-Kinases; D010768:Phosphoserine / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000037:antagonists & inhibitors / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D020104:Immunophilins; D008024:Ligands; D019869:Phosphatidylinositol 3-Kinases; D010768:Phosphoserine; D017853:Phosphotransferases (Alcohol Group Acceptor); D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D020123:Sirolimus; D022021:Tacrolimus Binding Proteins; D014446:Tyrosine 3-Monooxygenase; C075852:BMH1 protein, S cerevisiae; C097164:BMH2 protein, S cerevisiae; C083324:TOR1 protein, S cerevisiae