title: Std1p (Msn3p) positively regulates the Snf1 kinase in Saccharomyces cerevisiae.
abstract: The Snf1 protein kinase of the glucose signaling pathway in Saccharomyces cerevisiae is regulated by an autoinhibitory interaction between the regulatory and catalytic domains of Snf1p. Transitions between the autoinhibited and active states are controlled by an upstream kinase and the Reg1p-Glc7p protein phosphatase 1. Previous studies suggested that Snf1 kinase activity is also modulated by Std1p (Msn3p), which interacts physically with Snf1p and also interacts with glucose sensors. Here we address the relationship between Std1p and the Snf1 kinase. Two-hybrid assays showed that Std1p interacts with the catalytic domain of Snf1p, and analysis of mutant kinases suggested that this interaction is incompatible with the autoinhibitory interaction of the regulatory and catalytic domains. Overexpression of Std1p increased the two-hybrid interaction of Snf1p with its activating subunit Snf4p, which is diagnostic of an open, uninhibited conformation of the kinase complex. Overexpression of Std1p elevated Snf1 kinase activity in both in vitro and in vivo assays. These findings suggest that Std1p stimulates the Snf1 kinase by an interaction with the catalytic domain that antagonizes autoinhibition and promotes an active conformation of the kinase.
authors.affiliation: Department of Genetics, Columbia University, New York, New York 10032, USA.
authors.forename: Sergei
authors.initials: S
authors.lastname: Kuchin
authors.forename: Valmik K
authors.initials: VK
authors.lastname: Vyas
authors.forename: Ellen
authors.initials: E
authors.lastname: Kanter
authors.forename: Seung-Pyo
authors.initials: SP
authors.lastname: Hong
authors.forename: Marian
authors.initials: M
authors.lastname: Carlson
mesh_terms: D001681:Biological Assay; D005656:Fungal Proteins / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C081335:STD1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; D005947:Glucose; D005990:Glycerol; D005690:Galactose