Yeast SNF1 protein kinase interacts with SIP4, a C6 zinc cluster transcriptional activator: a new role for SNF1 in the glucose response.
The SNF1 protein kinase has been widely conserved in plants and mammals. In Saccharomyces cerevisiae, SNF1 is essential for expression of glucose-repressed genes in response to glucose deprivation. Previous studies supported a role for SNF1 in relieving transcriptional repression. Here, we report evidence that SNF1 modulates function of a transcriptional activator, SIP4, which was identified in a two-hybrid screen for interaction with SNF1. The N terminus of the predicted 96-kDa SIP4 protein is homologous to the DNA-binding domain of the GAL4 family of transcriptional activators, with a C6 zinc cluster adjacent to a coiled-coil motif The C terminus contains a leucine zipper motif and an acidic region. When bound to DNA, a LexA-SIP4 fusion activates transcription of a reporter gene. Transcriptional activation by SIP4 is regulated by glucose and depends on the SNF1 protein kinase. Moreover, SIP4 is differentially phosphorylated in response to glucose availability, and phosphorylation requires SNF1. These findings suggest that the SNF1 kinase interacts with a transcriptional activator to modulate its activity and provide the first direct evidence for a role of SNF1 in activating transcription in response to glucose limitation.
Lesage
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P
Department of Genetics and Development, Institute of Cancer Research, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
Yang
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X
Carlson
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M
D000595:Amino Acid Sequence; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D003001:Cloning, Molecular; D016384:Consensus Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D015534:Trans-Activators / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000096:biosynthesis
D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; C099279:SIP4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; D001616:beta-Galactosidase; D005947:Glucose