Phosphorylation of Cdc28 and regulation of cell size by the protein kinase CKII in Saccharomyces cerevisiae

2000 ◽  
Vol 351 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Gian Luigi RUSSO ◽  
Christian VAN DEN BOS ◽  
Ann SUTTON ◽  
Paola COCCETTI ◽  
Maurizio D. BARONI ◽  
...  

The CDK (cyclin-dependent kinase) family of enzymes is required for the G1-to-S-phase and G2-to-M-phase transitions during the cell-division cycle of eukaryotes. We have shown previously that the protein kinase CKII catalyses the phosphorylation of Ser-39 in Cdc2 during the G1 phase of the HeLa cell-division cycle [Russo, Vandenberg, Yu, Bae, Franza and Marshak (1992) J. Biol. Chem. 267, 20317–20325]. To identify a functional role for this phosphorylation, we have studied the homologous enzymes in the budding yeast Saccharomyces cerevisiae. The S. cerevisiae homologue of Cdc2, Cdc28, contains a consensus CKII site (Ser-46), which is homologous with that of human Cdc2. Using in vitro kinase assays, metabolic labelling, peptide mapping and phosphoamino acid analysis, we demonstrate that this site is phosphorylated in Cdc28 in vivo as well in vitro. In addition, S. cerevisiae cells in which Ser-46 has been mutated to alanine show a decrease in both cell volume and protein content of 33%, and this effect is most pronounced in the stationary phase. Because cell size in S. cerevisiae is regulated primarily at the G1 stage, we suggest that CKII contributes to the regulation of the cell cycle in budding yeast by phosphorylation of Cdc28 as a checkpoint for G1 progression.

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 467-476
Author(s):  
Bong-Kwan Han ◽  
Rodolfo Aramayo ◽  
Michael Polymenis

Abstract How organelle biogenesis and inheritance is linked to cell division is poorly understood. In the budding yeast Saccharomyces cerevisiae the G1 cyclins Cln1,2,3p control initiation of cell division. Here we show that Cln3p controls vacuolar (lysosomal) biogenesis and segregation. First, loss of Cln3p, but not Cln1p or Cln2p, resulted in vacuolar fragmentation. Although the vacuoles of cln3Δ cells were fragmented, together they occupied a large space, which accounted for a significant fraction of the overall cell size increase in cln3Δ cells. Second, cytosol prepared from cells lacking Cln3p had reduced vacuolar homotypic fusion activity in cell-free assays. Third, vacuolar segregation was perturbed in cln3Δ cells. Our findings reveal a novel role for a eukaryotic G1 cyclin in cytoplasmic organelle biogenesis and segregation.


1987 ◽  
Vol 7 (4) ◽  
pp. 1371-1377 ◽  
Author(s):  
T Toda ◽  
S Cameron ◽  
P Sass ◽  
M Zoller ◽  
J D Scott ◽  
...  

We have cloned a gene (BCY1) from the yeast Saccharomyces cerevisiae that encodes a regulatory subunit of the cyclic AMP-dependent protein kinase. The encoded protein has a structural organization similar to that of the RI and RII regulatory subunits of the mammalian cyclic AMP-dependent protein kinase. Strains of S. cerevisiae with disrupted BCY1 genes do not display a cyclic AMP-dependent protein kinase in vitro, fail to grow on many carbon sources, and are exquisitely sensitive to heat shock and starvation.


2019 ◽  
Vol 21 (11) ◽  
pp. 1382-1392 ◽  
Author(s):  
Athanasios Litsios ◽  
Daphne H. E. W. Huberts ◽  
Hanna M. Terpstra ◽  
Paolo Guerra ◽  
Alexander Schmidt ◽  
...  

2006 ◽  
Vol 26 (3) ◽  
pp. 912-928 ◽  
Author(s):  
Dagmar M. Truckses ◽  
Joshua E. Bloomekatz ◽  
Jeremy Thorner

ABSTRACT In Saccharomyces cerevisiae, pheromone response requires Ste5 scaffold protein, which ensures efficient G-protein-dependent recruitment of mitogen-activated protein kinase (MAPK) cascade components Ste11 (MAPK kinase kinase), Ste7 (MAPK kinase), and Fus3 (MAPK) to the plasma membrane for activation by Ste20 protein kinase. Ste20, which phosphorylates Ste11 to initiate signaling, is activated by binding to Cdc42 GTPase (membrane anchored via its C-terminal geranylgeranylation). Less clear is how activated and membrane-localized Ste20 contacts Ste11 to trigger invasive growth signaling, which also requires Ste7 and the MAPK Kss1, but not Ste5. Ste50 protein associates constitutively via an N-terminal sterile-alpha motif domain with Ste11, and this interaction is required for optimal invasive growth and hyperosmotic stress (high-osmolarity glycerol [HOG]) signaling but has a lesser role in pheromone response. We show that a conserved C-terminal, so-called “Ras association” (RA) domain in Ste50 is also essential for invasive growth and HOG signaling in vivo. In vitro the Ste50 RA domain is not able to associate with Ras2, but it does associate with Cdc42 and binds to a different face than does Ste20. RA domain function can be replaced by the nine C-terminal, plasma membrane-targeting residues (KKSKKCAIL) of Cdc42, and membrane-targeted Ste50 also suppresses the signaling deficiency of cdc42 alleles specifically defective in invasive growth. Thus, Ste50 serves as an adaptor to tether Ste11 to the plasma membrane and can do so via association with Cdc42, thereby permitting the encounter of Ste11 with activated Ste20.


1991 ◽  
Vol 11 (6) ◽  
pp. 3027-3036 ◽  
Author(s):  
M Ramirez ◽  
R C Wek ◽  
A G Hinnebusch

The GCN4 gene of the yeast Saccharomyces cerevisiae encodes a transcriptional activator of amino acid biosynthetic genes that is regulated at the translational level according to the availability of amino acids. GCN2 is a protein kinase required for increased translation of GCN4 mRNA in amino acid-starved cells. Centrifugation of cell extracts in sucrose gradients indicated that GCN2 comigrates with ribosomal subunits and polysomes. The fraction of GCN2 cosedimenting with polysomes was reduced under conditions in which polysomes were dissociated, suggesting that GCN2 is physically bound to these structures. When the association of 40S and 60S subunits was prevented by omitting Mg2+ from the gradient, almost all of the GCN2 comigrated with 60S ribosomal subunits, and it remained bound to these particles during gel electrophoresis under nondenaturing conditions. GCN2 could be dissociated from 60S subunits by 0.5 M KCl, suggesting that it is loosely associated with ribosomes rather than being an integral ribosomal protein. Accumulation of GCN2 on free 43S-48S particles and 60S subunits occurred during polysome runoff in vitro and under conditions of reduced growth rate in vivo. These observations, plus the fact that GCN2 shows preferential association with free ribosomal subunits during exponential growth, suggest that GCN2 interacts with ribosomes during the translation initiation cycle. The extreme carboxyl-terminal segment of GCN2 is essential for its interaction with ribosomes. These sequences are also required for the ability of GCN2 to stimulate GCN4 translation in vivo, leading us to propose that ribosome association by GCN2 is important for its access to substrates in the translational machinery or for detecting uncharged tRNA in amino acid-starved cells.


1992 ◽  
Vol 70 (10-11) ◽  
pp. 946-953
Author(s):  
Adele Rowley ◽  
Gerald C. Johnston ◽  
Richard A. Singer

The eukaryotic cell cycle is regulated at two points, the G1-S and G2-M boundaries. The molecular basis for these regulatory activities has recently been elucidated, in large part by the use of molecular and genetic analyses using unicellular yeast. The molecular characterization of cell-cycle regulation has revealed striking functional conservation among evolutionarily diverse cell types. For many eukaryotic cells, regulation of cell proliferation occurs primarily in the G1 interval. The G2 regulatory step, termed start, requires the activation of a highly conserved p34 protein kinase by association with a functionally redundant family of proteins, the G1 cyclins. Here we review studies using the genetically tractable budding yeast Saccharomyces cerevisiae, which have provided insight into the role of G1 cyclins in the regulation of start.Key words: cell cycle, cyclin proteins, cdc2 protein kinase, start.


1987 ◽  
Vol 7 (4) ◽  
pp. 1371-1377 ◽  
Author(s):  
T Toda ◽  
S Cameron ◽  
P Sass ◽  
M Zoller ◽  
J D Scott ◽  
...  

We have cloned a gene (BCY1) from the yeast Saccharomyces cerevisiae that encodes a regulatory subunit of the cyclic AMP-dependent protein kinase. The encoded protein has a structural organization similar to that of the RI and RII regulatory subunits of the mammalian cyclic AMP-dependent protein kinase. Strains of S. cerevisiae with disrupted BCY1 genes do not display a cyclic AMP-dependent protein kinase in vitro, fail to grow on many carbon sources, and are exquisitely sensitive to heat shock and starvation.


1991 ◽  
Vol 11 (6) ◽  
pp. 3027-3036 ◽  
Author(s):  
M Ramirez ◽  
R C Wek ◽  
A G Hinnebusch

The GCN4 gene of the yeast Saccharomyces cerevisiae encodes a transcriptional activator of amino acid biosynthetic genes that is regulated at the translational level according to the availability of amino acids. GCN2 is a protein kinase required for increased translation of GCN4 mRNA in amino acid-starved cells. Centrifugation of cell extracts in sucrose gradients indicated that GCN2 comigrates with ribosomal subunits and polysomes. The fraction of GCN2 cosedimenting with polysomes was reduced under conditions in which polysomes were dissociated, suggesting that GCN2 is physically bound to these structures. When the association of 40S and 60S subunits was prevented by omitting Mg2+ from the gradient, almost all of the GCN2 comigrated with 60S ribosomal subunits, and it remained bound to these particles during gel electrophoresis under nondenaturing conditions. GCN2 could be dissociated from 60S subunits by 0.5 M KCl, suggesting that it is loosely associated with ribosomes rather than being an integral ribosomal protein. Accumulation of GCN2 on free 43S-48S particles and 60S subunits occurred during polysome runoff in vitro and under conditions of reduced growth rate in vivo. These observations, plus the fact that GCN2 shows preferential association with free ribosomal subunits during exponential growth, suggest that GCN2 interacts with ribosomes during the translation initiation cycle. The extreme carboxyl-terminal segment of GCN2 is essential for its interaction with ribosomes. These sequences are also required for the ability of GCN2 to stimulate GCN4 translation in vivo, leading us to propose that ribosome association by GCN2 is important for its access to substrates in the translational machinery or for detecting uncharged tRNA in amino acid-starved cells.


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