title: Quantitative proteomics identifies unanticipated regulators of nitrogen- and glucose starvation.
abstract: The molecular mechanisms underlying how cells sense, respond, and adapt to alterations in nutrient availability have been studied extensively during the past years. While most of these studies have focused on the linear connections between signaling components, it is increasingly being recognized that signaling pathways are interlinked in molecular circuits and networks such that any metabolic perturbation will induce signaling-wide ripple effects. In the present study, we have used quantitative mass spectrometry (MS) to examine how the yeast Saccharomyces cerevisiae responds to nitrogen- or glucose starvation. We identify nearly 1400 phosphorylation sites of which more than 500 are regulated in a temporal manner in response to glucose- or nitrogen starvation. By bioinformatics and network analyses, we have identified the cyclin-dependent kinase (CDK) inhibitor Sic1, the Hsp90 co-chaperone Cdc37, and the Hsp90 isoform Hsp82 to putatively mediate some of the starvation responses. Consistently, quantitative expression analyses showed that Sic1, Cdc37, and Hsp82 are required for normal expression of nutrient-responsive genes. Collectively, we therefore propose that Sic1, Cdc37, and Hsp82 may orchestrate parts of the cellular starvation response by regulating transcription factor- and kinase activities.
authors.affiliation: Villum Center for Bioanalytical Sciences, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark. nils.f@bmb.sdu.dk.
authors.forename: Steven V
authors.initials: SV
authors.lastname: Rødkær
authors.forename: Dennis
authors.initials: D
authors.lastname: Pultz
authors.forename: Michelle
authors.initials: M
authors.lastname: Brusch
authors.forename: Martin V
authors.initials: MV
authors.lastname: Bennetzen
authors.forename: Lasse G
authors.initials: LG
authors.lastname: Falkenby
authors.forename: Jens S
authors.initials: JS
authors.lastname: Andersen
authors.forename: Nils J
authors.initials: NJ
authors.lastname: Færgeman
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D050756:Cyclin-Dependent Kinase Inhibitor Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D013058:Mass Spectrometry; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010766:Phosphorylation; D040901:Proteomics / Q000379:methods*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: C513270:CDC37 protein, S cerevisiae; D018797:Cell Cycle Proteins; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005947:Glucose; D009584:Nitrogen