Glucose regulates protein interactions within the yeast SNF1 protein kinase complex.
The SNF1 protein kinase is broadly conserved in eukaryotes and has been implicated in responses to environmental and nutritional stress. In yeast, the SNF1 kinase has a central role in the response to glucose starvation. SNF1 is associated with its activating subunit, SNF4, and other proteins in complexes. Using the two-hybrid system, we show that interaction between SNF1 and SNF4 is strongly regulated by the glucose signal. Moreover, this interaction is appropriately affected by mutations in regulators, including protein phosphatase 1. We show that SNF4 binds to the SNF1 regulatory domain in low glucose, whereas in high glucose the regulatory domain binds to the kinase domain of SNF1 itself. Genetic analysis further suggests that the SNF1 regulatory domain autoinhibits the kinase activity and that in low glucose SNF4 antagonizes this inhibition. Finally, these interactions have been conserved from yeast to plants, indicating that homologs of the SNF1 kinase complex respond to regulatory signals by analogous mechanisms.
Jiang
R
R
Department of Genetics, Columbia University, New York, New York 10032, USA.
Carlson
M
M
D055372:AMP-Activated Protein Kinases; D000595:Amino Acid Sequence; D002352:Carrier Proteins; D005656:Fungal Proteins / Q000378:metabolism; D005947:Glucose / Q000502:physiology*; D006593:Hexokinase / Q000502:physiology; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000502:physiology*; D054645:Protein Phosphatase 1; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D014157:Transcription Factors / Q000502:physiology*
D002352:Carrier Proteins; D005656:Fungal Proteins; D046911:Macromolecular Substances; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases; C071570:SNF1-related protein kinases; D006593:Hexokinase; D017346:Protein Serine-Threonine Kinases; C078651:SNF4 protein, S cerevisiae; D055372:AMP-Activated Protein Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D005947:Glucose