title: Protein kinases are associated with multiple, distinct cytoplasmic granules in quiescent yeast cells.
abstract: The cytoplasm of the eukaryotic cell is subdivided into distinct functional domains by the presence of a variety of membrane-bound organelles. The remaining aqueous space may be further partitioned by the regulated assembly of discrete ribonucleoprotein (RNP) complexes that contain particular proteins and messenger RNAs. These RNP granules are conserved structures whose importance is highlighted by studies linking them to human disorders like amyotrophic lateral sclerosis. However, relatively little is known about the diversity, composition, and physiological roles of these cytoplasmic structures. To begin to address these issues, we examined the cytoplasmic granules formed by a key set of signaling molecules, the protein kinases of the budding yeast Saccharomyces cerevisiae. Interestingly, a significant fraction of these proteins, almost 20%, was recruited to cytoplasmic foci specifically as cells entered into the G0-like quiescent state, stationary phase. Colocalization studies demonstrated that these foci corresponded to eight different granules, including four that had not been reported previously. All of these granules were found to rapidly disassemble upon the resumption of growth, and the presence of each was correlated with cell viability in the quiescent cultures. Finally, this work also identified new constituents of known RNP granules, including the well-characterized processing body and stress granule. The composition of these latter structures is therefore more varied than previously thought and could be an indicator of additional biological activities being associated with these complexes. Altogether, these observations indicate that quiescent yeast cells contain multiple distinct cytoplasmic granules that may make important contributions to their long-term survival.
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Khyati H
authors.initials: KH
authors.lastname: Shah
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Regina
authors.initials: R
authors.lastname: Nostramo
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Sapna N
authors.initials: SN
authors.lastname: Varia
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210.
authors.forename: Bethany M
authors.initials: BM
authors.lastname: Klett
authors.affiliation: Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210 herman.81@osu.edu.
authors.forename: Paul K
authors.initials: PK
authors.lastname: Herman
mesh_terms: D000199:Actins / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D016192:Resting Phase, Cell Cycle; D012261:Ribonucleoproteins / Q000737:chemistry / Q000378:metabolism; D013312:Stress, Physiological; D015003:Yeasts / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000199:Actins; D005656:Fungal Proteins; D012261:Ribonucleoproteins; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D005947:Glucose
keywords: P-bodies; protein kinases; ribonucleoprotein (RNP) granules; stationary phase; stress granules