Mutational analysis of the Saccharomyces cerevisiae SNF1 protein kinase and evidence for functional interaction with the SNF4 protein.
The SNF1 gene of Saccharomyces cerevisiae encodes a protein-serine/threonine kinase that is required for derepression of gene expression in response to glucose limitation. We present evidence that the protein kinase activity is essential for SNF1 function: substitution of Arg for Lys in the putative ATP-binding site results in a mutant phenotype. A polyhistidine tract near the N terminus was found to be dispensable. Deletion of the large region C terminal to the kinase domain only partially impaired SNF1 function, causing expression of invertase to be somewhat reduced but still glucose repressible. The function of the SNF4 gene, another component of the regulatory system, was required for maximal in vitro activity of the SNF1 protein kinase. Increased SNF1 gene dosage partially alleviated the requirement for SNF4. C-terminal deletions of SNF1 also reduced dependence on SNF4. Our findings suggest that SNF4 acts as a positive effector of the kinase but does not serve a regulatory function in signaling glucose availability.
Celenza
J L
JL
Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, New York, New York 10032.
Carlson
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004252:DNA Mutational Analysis; D004303:Dosage Compensation, Genetic; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005838:Genotype; D005947:Glucose / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000096:biosynthesis; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D043324:beta-Fructofuranosidase
D005656:Fungal Proteins; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D006026:Glycoside Hydrolases; D043324:beta-Fructofuranosidase; D005947:Glucose