The Cellular Content of Cdc25p, the Ras Exchange Factor in Saccharomyces cerevisiae, Is Regulated by Destabilization Through a Cyclin Destruction Box

Kapłon, Tomasz; Jacquet, Michel

doi:10.1074/jbc.270.35.20742

Cited by 37 publications

(29 citation statements)

References 45 publications

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“…In this context, it is worth mentioning that the expression of C-CDC25 Mm285 in fibroblasts was found to enhance the GDP/GTP exchange activity on H-ras p21 and the tumor formation in the nude mice (35). Moreover, the homologous Saccharomyces cerevisiae ras-GEF Cdc25p, containing a cyclin destruction box, has been described to display a rapid metabolism (half-life time, ϳ20 min) due to proteolytic degradation (36). Whether proteases also act on the mammalian rasGEF in vivo remains to be determined, since the half-life of CDC25 Mm in neuronal cells is still unknown.…”

Section: Discussionmentioning

confidence: 99%

The N-terminal Moiety of CDC25Mm, a GDP/GTP Exchange Factor of Ras Proteins, Controls the Activity of the Catalytic Domain

Baouz

Jacquet

Bernardi

et al. 1997

Journal of Biological Chemistry

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This work describes the in vitro properties of fulllength CDC25 Mm (1262 amino acid residues), a GDP/GTP exchange factor (GEF) of H-ras p21. CDC25 Mm , isolated as a recombinant protein in Escherichia coli and purified by various chromatographic methods, could stimulate the H-ras p21⅐GDP dissociation rate; however, its specific activity was 25 times lower than that of the isolated catalytic domain comprising the last C-terminal 285 residues (C-CDC25 Mm285 ) and 5 times lower than the activity of the C-terminal half-molecule (631 residues). This reveals a negative regulation of the catalytic domain by other domains of the molecule. Accordingly, the GEF activity of CDC25 Mm was increased severalfold by the Ca 2؉ -dependent protease calpain that cleaves around a PEST-like region (residues 798 -853), producing C-terminal fragments of 43-56 kDa. In agreement with the presence of an IQ motif on CDC25 Mm (residues 202-229), calmodulin interacted functionally with the exchange factor. Depending on the calmodulin concentration an inhibition up to 50% of the CDC25 Mm -induced nucleotide exchange activity on H-ras p21 was observed, an effect requiring Ca 2؉ ions. Calmodulin also inhibited C-CDC25 Mm285 but with a ϳ100 times higher IC 50 than in the case of CDC25 Mm (ϳ10 M versus 0.1 M, respectively). Together, these results emphasize the role of the other domains of CDC25 Mm in controlling the activity of the catalytic domain and support the involvement of calmodulin and calpain in the in vivo regulation of the CDC25 Mm activity.The mouse CDC25 Mm 1 protein is a guanine nucleotide exchange factor (GEF) regenerating the active form of H-ras p21, the complex with GTP (1-3). Homologous products were found in rat (p140-rasGRF) (4) and human (H-GRF) (5, 6). These rasGEFs have been described to be specific for the central nervous system (4 -9). Some evidence has also been reported for the existence of full-length and truncated forms of these exchange factors in other tissues (10,11). Experiments in vivo suggest that the upstream connection of this GEF involves G-protein-coupled receptors (9, 12, 13) and not hormone-receptor-bound tyrosine kinases via the adaptor protein GRB2, as has been found for SOS, a ubiquitous rasGEF (14 -16). CDC25 Mm contains in the N-terminal moiety two domains of pleckstrin homology (PH1 and PH2), one of DBL homology (DH) and a coiled-coil region that follows the PH1 domain (cf. (21) and the DH is a domain sharing similarity with a GDP/GTP exchange factor of members of the Rho family (2,4,22,23). Farnsworth et al. (24) reported that in vivo the activity of the homologous p140-rasGRF from rat brain is enhanced by raising the calcium concentration, an effect associated with the binding of calmodulin, and that p140-rasGRF and calmodulin form a stable complex. A direct action of calmodulin was supported by the presence in the N-terminal region of CDC25 Mm of an IQ domain, a sequence frequently found in proteins interacting with calmodulin (25, 26). Very recent experiments in vivo have indicated that PH1, ...

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Section: Discussionmentioning

confidence: 99%

The N-terminal Moiety of CDC25Mm, a GDP/GTP Exchange Factor of Ras Proteins, Controls the Activity of the Catalytic Domain

Baouz

Jacquet

Bernardi

et al. 1997

Journal of Biological Chemistry

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“…The depletion of Cdc25p in S. cerevisiae could then be controlled either by arrest of its production, since it is an unstable protein that decays rapidly (Kaplon & Jacquet, 1995), or by increased degradation. Regulation of the cellular content of the protein has also been reported for a mammalian homologue of Cdc25p, the Ras-GRF2 which contains a CDB motif, also present in Cdc25p, and is controlled by ubiquitination and degradation via the proteasome (de Hoog et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Stress induces depletion of Cdc25p and decreases the cAMP producing capability in Saccharomyces cerevisiae

et al. 2004

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In Saccharomyces cerevisiae the cAMP-dependent protein kinase A pathway antagonizes the cellular response to stress. It is shown here that the cellular content of Cdc25p, the upstream activator of Ras and adenylyl cyclase, decays upon various stresses such as heat shock and oxidative and ethanol shocks, whereas its phosphorylation level and its localization are unaffected. In parallel with the reduction of Cdc25p, the maximal capacity of the cell to accumulate cAMP decreases when its feedback regulation is abolished. A deletion of CDC25 prevents this decrease. Paradoxically, in wild-type cells, with normal feedback regulation, the level of cAMP, which is much lower, is not reduced but is rather increased upon stress. These observations are consistent with a role of Cdc25p in sensing and transducing stress to downstream targets, either through a cAMP-independent pathway or by large fluctuations in the cAMP content of the cell.

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“…It could be that the Sdc25p is less stable than Cdc25p and then greater expression is needed to reach the same level of protein. One property of the Cdc25 protein is its instability due to a cyclin destruction box (Kaplon and Jacquet, 1995). A great instability of the Sdc25 protein is also suspected.…”

Section: Discussionmentioning

confidence: 99%

SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation.

Boy‐Marcotte

Ikonomi

Jacquet

1996

MBoC

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The Cellular Content of Cdc25p, the Ras Exchange Factor in Saccharomyces cerevisiae, Is Regulated by Destabilization Through a Cyclin Destruction Box

Cited by 37 publications

References 45 publications

The N-terminal Moiety of CDC25Mm, a GDP/GTP Exchange Factor of Ras Proteins, Controls the Activity of the Catalytic Domain

The N-terminal Moiety of CDC25Mm, a GDP/GTP Exchange Factor of Ras Proteins, Controls the Activity of the Catalytic Domain

Stress induces depletion of Cdc25p and decreases the cAMP producing capability in Saccharomyces cerevisiae

SDC25, a dispensable Ras guanine nucleotide exchange factor of Saccharomyces cerevisiae differs from CDC25 by its regulation.

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