title: Widespread reorganization of metabolic enzymes into reversible assemblies upon nutrient starvation.
abstract: Proteins are likely to organize into complexes that assemble and disassemble depending on cellular needs. When approximately 800 yeast strains expressing GFP-tagged proteins were grown to stationary phase, a surprising number of proteins involved in intermediary metabolism and stress response were observed to form punctate cytoplasmic foci. The formation of these discrete physical structures was confirmed by immunofluorescence and mass spectrometry of untagged proteins. The purine biosynthetic enzyme Ade4-GFP formed foci in the absence of adenine, and cycling between punctate and diffuse phenotypes could be controlled by adenine subtraction and addition. Similarly, glutamine synthetase (Gln1-GFP) foci cycled reversibly in the absence and presence of glucose. The structures were neither targeted for vacuolar or autophagosome degradation nor colocalized with P bodies or major organelles. Thus, upon nutrient depletion we observe widespread protein assemblies displaying nutrient-specific formation and dissolution.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas, Institute for Cellular and Molecular Biology, Center for Systems and Synthetic Biology, Austin, TX 78712-1064, USA.
authors.forename: Rammohan
authors.initials: R
authors.lastname: Narayanaswamy
authors.forename: Matthew
authors.initials: M
authors.lastname: Levy
authors.forename: Mark
authors.initials: M
authors.lastname: Tsechansky
authors.forename: Gwendolyn M
authors.initials: GM
authors.lastname: Stovall
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: O'Connell
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mirrielees
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Ellington
authors.forename: Edward M
authors.initials: EM
authors.lastname: Marcotte
mesh_terms: D003593:Cytoplasm / Q000201:enzymology; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000096:biosynthesis; D013058:Mass Spectrometry; D009097:Multienzyme Complexes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D014617:Vacuoles / Q000201:enzymology
chemical_list: D009097:Multienzyme Complexes; D049452:Green Fluorescent Proteins