Concerted mechanism of Swe1/Wee1 regulation by multiple kinases in budding yeast (original) (raw)
Related papers
Cdc5 Interacts with the Wee1 Kinase in Budding Yeast
Molecular and Cellular Biology, 2001
Development of a multicellular organism requires that mitosis and morphogenesis be coordinated. These processes must also be synchronized during the growth of unicellular organisms. In the yeast Saccharomyces cerevisiae, mitosis is dependent on the prior growth of a daughter cell in the form of a bud. Overexpression of wild-type Polo-like kinase Cdc5 or a catalytically inactive form resulted in the formation of multinucleate cells in budding yeast. Immunofluorescence analysis of these multinulceate cells showed that mitosis and bud formation were no longer linked. Others have shown that Swe1 is required for coupling mitosis to bud formation during a perturbed cell cycle. When the normal pathway of bud formation is perturbed, Swe1 functions to delay mitosis through negative regulation of Clb/Cdk. In cells lacking Swe1, multinucleate cells are formed in response to delays in bud formation. Affinity purification, two-hybrid analysis, and mutant characterization results suggested that Cdc5 and Swe1 interact. From these results, we conclude that multinucleate formation in response to Cdc5 overexpression is linked to titration of Swe1 function. These results also suggest that Cdc5 may be a negative regulator of Swe1.
Novel Functional Dissection of the Localization-Specific Roles of Budding Yeast Polo Kinase Cdc5p
Molecular and Cellular Biology, 2004
Budding yeast polo kinase Cdc5p localizes to the spindle pole body (SPB) and to the bud-neck and plays multiple roles during M-phase progression. To dissect localization-specific mitotic functions of Cdc5p, we tethered a localization-defective N-terminal kinase domain of Cdc5p (Cdc5pΔC) to the SPB or to the bud-neck with components specifically localizing to one of these sites and characterized these mutants in a cdc5Δ background. Characterization of a viable, SPB-localizing, CDC5ΔC-CNM67 mutant revealed that it is defective in timely degradation of Swe1p, a negative regulator of Cdc28p. Loss of BFA1 , a negative regulator of mitotic exit, rescued the lethality of a neck-localizing CDC5ΔC-CDC12 or CDC5ΔC-CDC3 mutant but yielded severe defects in cytokinesis. These data suggest that the SPB-associated Cdc5p activity is critical for both mitotic exit and cytokinesis, whereas the bud neck-localized Cdc5p is required for proper Swe1p regulation. Interestingly, a cdc5Δ bfa1Δ swe1Δ triple...
Coupling morphogenesis to mitotic entry
Proceedings of the National Academy of Sciences of the United States of America, 2004
In eukaryotes, cyclin B-bound cyclin-dependent protein kinase 1 promotes mitotic entry but is held in check, in part, by Wee1 protein kinase. Timely mitotic entry in budding yeast requires inactivation of Swe1 (Wee1 ortholog). Perturbations of the septin collar at the bud neck lead to Swe1 stabilization, delaying the G2/M transition. Swe1 is recruited to the neck and hyperphosphorylated before ubiquitin-mediated degradation. Hsl1 kinase (Nim1 ortholog), a negative regulator of Wee1, is required for efficient Swe1 localization at the neck but seems not to phosphorylate Swe1. Here, we show that two other kinases targeted sequentially to the neck, Cla4/PAK and Cdc5/Polo, are responsible for stepwise phosphorylation and down-regulation of Swe1. This mechanism links assembly of a cellular structure to passage into mitosis. Cdk1 regulation | mitotic progression | G2/M transition | Saccharomyces cerevisiae
Current Biology, 1998
Background: Following chromosome segregation in anaphase, ubiquitindependent degradation of mitotic cyclins contributes to the exit from mitosis. A key step in this process is catalyzed by a ubiquitin-protein ligase known as the anaphase-promoting complex (APC), the regulation of which is poorly understood. The Polo-related protein kinase Cdc5 in Saccharomyces cerevisiae might encode a regulator of the APC, because cdc5 mutant cells arrest with a late mitotic phenotype similar to that observed in cells with defective cyclin destruction.
Swe1 and Mih1 regulate mitotic spindle dynamics in budding yeast via Bik1
Journal of Cell Science
The mitotic spindle is a very dynamic structure that is built de novo and destroyed at each round of cell division. In order to perform its fundamental function during chromosome segregation, mitotic spindle dynamics must be tightly coordinated with other cell cycle events. These changes are driven by several protein kinases, phosphatases and microtubule-associated proteins. In budding yeast, the kinase Swe1 and the phosphatase Mih1 act in concert in controlling the phosphorylation state of Cdc28, the catalytic subunit of Cdk1, the major regulator of the cell cycle. In this study we show that Swe1 and Mih1 are also involved in the control of mitotic spindle dynamics. Our data indicate that Swe1 and the Polo-like kinase Cdc5 control the balance between phosphorylated and unphosphorylated forms of Mih1, which is, in turn, important for mitotic spindle elongation. Moreover, we show that the microtubule-associated protein Bik1 is a phosphoprotein, and that Swe1 and Mih1 are both involved in controlling phosphorylation of Bik1. These results uncover new players and provide insights into the complex regulation of mitotic spindle dynamics.
Genetics, 2003
In many organisms, polo kinases appear to play multiple roles during M-phase progression. To provide new insights into the function of budding yeast polo kinase Cdc5p, we generated novel temperature-sensitive cdc5 mutants by mutagenizing the C-terminal domain. Here we show that, at a semipermissive temperature, the cdc5-3 mutant exhibited a synergistic bud elongation and growth defect with loss of HSL1, a component important for normal G2/M transition. Loss of SWE1, which phosphorylates and inactivates the budding yeast Cdk1 homolog Cdc28p, suppressed the cdc5-3 hsl1Δ defect, suggesting that Cdc5p functions at a point upstream of Swe1p. In addition, the cdc5-4 and cdc5-7 mutants exhibited chained cell morphologies with shared cytoplasms between the connected cell bodies, indicating a cytokinetic defect. Close examination of these mutants revealed delayed septin assembly at the incipient bud site and loosely organized septin rings at the mother-bud neck. Components in the mitotic exi...
A phosphatase threshold sets the level of Cdk1 activity in early mitosis in budding yeast
2011
Entry into mitosis is initiated by synthesis of cyclins, which bind and activate cyclin-dependent kinase 1 (Cdk1). Cyclin synthesis is gradual, yet activation of Cdk1 occurs in a stepwise manner: a low level of Cdk1 activity is initially generated that triggers early mitotic events, which is followed by full activation of Cdk1. Little is known about how stepwise activation of Cdk1 is achieved. A key regulator of Cdk1 is the Wee1 kinase, which phosphorylates and inhibits Cdk1. Wee1 and Cdk1 show mutual regulation: Cdk1 phosphorylates Wee1, which activates Wee1 to inhibit Cdk1. Further phosphorylation events inactivate Wee1. We discovered that a specific form of protein phosphatase 2A (PP2A Cdc55) opposes the initial phosphorylation of Wee1 by Cdk1. In vivo analysis, in vitro reconstitution, and mathematical modeling suggest that PP2A Cdc55 sets a threshold that limits activation of Wee1, thereby allowing a low constant level of Cdk1 activity to escape Wee1 inhibition in early mitosis. These results define a new role for PP2A Cdc55 and reveal a systems-level mechanism by which dynamically opposed kinase and phosphatase activities can modulate signal strength.
Genes & Development, 1999
The mechanisms that couple cell cycle progression with the organization of the peripheral cytoskeleton are poorly understood. In Saccharomyces cerevisiae, the Swe1 protein has been shown previously to phosphorylate and inactivate the cyclin-dependent kinase, Cdc28, thereby delaying the onset of mitosis. The nim1-related protein kinase, Hsl1, induces entry into mitosis by negatively regulating Swe1. We have found that Hsl1 physically associates with the septin cytoskeleton in vivo and that Hsl1 kinase activity depends on proper septin function. Genetic analysis indicates that two additional Hsl1-related kinases, Kcc4 and Gin4, act redundantly with Hsl1 to regulate Swe1. Kcc4, like Hsl1 and Gin4, was found to localize to the bud neck in a septin-dependent fashion. Interestingly, hsl1 kcc4 gin4 triple mutants develop a cellular morphology extremely similar to that of septin mutants. Consistent with the idea that Hsl1, Kcc4, and Gin4 link entry into mitosis to proper septin organization, we find that septin mutants incubated at the restrictive temperature trigger a Swe1-dependent mitotic delay that is necessary to maintain cell viability. These results reveal for the first time how cells monitor the organization of their cytoskeleton and demonstrate the existence of a cell cycle checkpoint that responds to defects in the peripheral cytoskeleton. Moreover, Hsl1, Kcc4, and Gin4 have homologs in higher eukaryotes, suggesting that the regulation of Swe1/Wee1 by this class of kinases is highly conserved. ; FAX 432-6161. 176 GENES & DEVELOPMENT 13:176-187 © 1999 by Cold Spring Harbor Laboratory Press ISSN 0890-9369/99 $5.00; www.genesdev.org Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 177 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from Cytoskeletal checkpoint in yeast GENES & DEVELOPMENT 183 Cold Spring Harbor Laboratory Press on August 26, 2016 -Published by genesdev.cshlp.org Downloaded from