Requirement of Saccharomyces cerevisiae Ras for Completion of Mitosis

Abstract

In the yeast Saccharomyces cerevisiae, Ras regulates adenylate cyclase, which is essential for progression through the G1 phase of the cell cycle. However, even when the adenosine 3',5'-monophosphate (cAMP) pathway was bypassed, the double disruption of RAS1 and RAS2 resulted in defects in growth at both low and high temperatures. Furthermore, the simultaneous disruption of RAS1, RAS2, and the RAS-related gene RSR1 was lethal at any temperature. The triple-disrupted cells were arrested late in the mitotic (M) phase, which was accompanied by an accumulation of cells with divided chromosomes and sustained histone H1 kinase activity. The lethality of the triple disruption was suppressed by the multicopies of CDC5, CDC15, DBF2, SPO12, and TEM1, all of which function in the completion of the M phase. Mammalian ras also suppressed the lethality, which suggests that a similar signaling pathway exists in higher eukaryotes. These results demonstrate that S. cerevisiae Ras functions in the completion of the M phase in a manner independent of the Ras-cAMP pathway.

Long-chain alkyl ester of AMP acts as an antagonist of glucose-induced signal transduction that mediates activation of plasma membrane proton pump in Saccharomyces cerevisiae

“…Similar inhibition was also observed with AMPC16 but it was accompanied by an inhibition against vegetative cell growth, which was in agreement with a previous finding on the role of the AMP analogue as an inhibitor of longchain acyl-CoA synthetase (Shiraishi et al, 1994). In addition, the growth inhibition by AMPC16 may reflect its interference with a cAMP-dependent cell cycle mechanism (Hynie & Smrt, 1978 ;Morishita et al, 1995). In the present study, we examined the antimicrobial activities of these nucleotide analogues against a wide variety of bacteria, yeast and fungi, and characterized the mechanism of the Mg# + -dependent cytotoxic action of AMPC16 against Sac.…”

“…Sitespecific phosphorylation is likely to regulate the ATPase activity in response to nutritional signals. It is known that the cellular cAMP level shows a rapid increase under the above conditions in which H + -ATPasedependent proton extrusion occurs at the fully stimulated rate (Morishita et al, 1995), suggesting a cAMPdependent mechanism for the site-specific phosphorylation of the enzyme. However, yeast strains that are specifically deficient in the glucose-induced cAMP increase still show normal activation of plasma membrane H + -ATPase (Becher dos Passos et al, 1992).…”

The Ras/cAMP-dependent Protein Kinase Signaling Pathway Regulates an Early Step of the Autophagy Process in Saccharomyces cerevisiae

“…1A) (65, 66). Since the yeast Ras proteins have multiple effectors (2,30,67, 68), we tested whether this inhibition of autophagy was due to the cAMP/PKA effector pathway. For this analysis, a high copy plasmid containing the TPK1 gene was introduced into the assay strain.…”

MOB1, an Essential Yeast Gene Required for Completion of Mitosis and Maintenance of Ploidy

“…This event is a prerequisite for the completion of mitosis, as expression of an indestructible form of Clb2p in yeast causes a late nuclear division arrest (Surana et al, 1993). Strains harboring mutations in DBF2, CDC5, CDC15, CDC14, TEM1 or harboring triple deletions in the RAS1⌬, RAS2⌬, RSR1⌬ genes all arrest in late nuclear division with high Clb2p/Cdc28p kinase activity, suggesting they may be required for cyclin degradation and/or Cdc28p inactivation (Surana et al, 1993;Shirayama et al, 1994;Toyn and Johnston, 1994;Morishita et al, 1995). The APC/cyclosome is also necessary for targeting the spindle-associated protein, Ase1p, for degradation at the end of mitosis (Juang et al, 1997).…”