title: The proteomics of quiescent and nonquiescent cell differentiation in yeast stationary-phase cultures.
abstract: As yeast cultures enter stationary phase in rich, glucose-based medium, differentiation of two major subpopulations of cells, termed quiescent and nonquiescent, is observed. Differences in mRNA abundance between exponentially growing and stationary-phase cultures and quiescent and nonquiescent cells are known, but little was known about protein abundance in these cells. To measure protein abundance in exponential and stationary-phase cultures, the yeast GFP-fusion library (4159 strains) was examined during exponential and stationary phases, using high-throughput flow cytometry (HyperCyt). Approximately 5% of proteins in the library showed twofold or greater changes in median fluorescence intensity (abundance) between the two conditions. We examined 38 strains exhibiting two distinct fluorescence-intensity peaks in stationary phase and determined that the two fluorescence peaks distinguished quiescent and nonquiescent cells, the two major subpopulations of cells in stationary-phase cultures. GFP-fusion proteins in this group were more abundant in quiescent cells, and half were involved in mitochondrial function, consistent with the sixfold increase in respiration observed in quiescent cells and the relative absence of Cit1p:GFP in nonquiescent cells. Finally, examination of quiescent cell-specific GFP-fusion proteins revealed symmetry in protein accumulation in dividing quiescent and nonquiescent cells after glucose exhaustion, leading to a new model for the differentiation of these cells.
authors.affiliation: Biology Department, University of New Mexico, Albuquerque, NM 87131, USA.
authors.forename: George S
authors.initials: GS
authors.lastname: Davidson
authors.forename: Ray M
authors.initials: RM
authors.lastname: Joe
authors.forename: Sushmita
authors.initials: S
authors.lastname: Roy
authors.forename: Osorio
authors.initials: O
authors.lastname: Meirelles
authors.forename: Chris P
authors.initials: CP
authors.lastname: Allen
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Wilson
authors.forename: Phillip H
authors.initials: PH
authors.lastname: Tapia
authors.forename: Elaine E
authors.initials: EE
authors.lastname: Manzanilla
authors.forename: Anne E
authors.initials: AE
authors.lastname: Dodson
authors.forename: Swagata
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Mark
authors.initials: M
authors.lastname: Carter
authors.forename: Susan
authors.initials: S
authors.lastname: Young
authors.forename: Bruce
authors.initials: B
authors.lastname: Edwards
authors.forename: Larry
authors.initials: L
authors.lastname: Sklar
authors.forename: Margaret
authors.initials: M
authors.lastname: Werner-Washburne
mesh_terms: D002453:Cell Cycle / Q000502:physiology; D005434:Flow Cytometry; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D010101:Oxygen Consumption; D040901:Proteomics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins