Localization of a 210-kDa microtubule-interacting protein in the yeast Saccharomyces cerevisiae

1992 ◽  
Vol 38 (2) ◽  
pp. 149-152 ◽  
Author(s):  
J. Hašek ◽  
J. Jochová ◽  
P. Dráber ◽  
V. Viklický ◽  
E. Streiblová

Using the monoclonal antibody MA-01, which recognizes a 210-kDa protein in cell-free extracts, spindle and cytoplasmic microtubules were visualized in budding yeast, Saccharomyces cerevisiae. In additional, a spot-like staining was found beneath the plasma membrane, revealing in part correlation with F-actin distribution. This pattern was common for cells of all cell-cycle stages. The interaction of the protein recognized by MA-01 with microtubules was confirmed in the double labeling with a polyclonal antitubulin antibody and by the sensitivity of intranuclear structures stained by MA-01 to the microtubule disrupting drug nocodazole. Key words: immunoblotting, immunofluorescence, microtubule-interacting protein, Saccharomyces cerevisiae.

Genetics ◽  
2002 ◽  
Vol 161 (2) ◽  
pp. 595-609
Author(s):  
Hyung-Seo Hwang ◽  
Kiwon Song

Abstract During mitosis, genomic integrity is maintained by the proper coordination of mitotic events through the spindle checkpoint. The bifurcated spindle checkpoint blocks cell cycle progression at metaphase by monitoring unattached kinetochores and inhibits mitotic exit in response to the incorrect orientation of the mitotic spindle. Bfa1p is a spindle checkpoint regulator of budding yeast in the Bub2p checkpoint pathway for proper mitotic exit. We have isolated a novel Bfa1p interacting protein named Ibd2p in the budding yeast Saccharomyces cerevisiae. We found that IBD2 (Inhibition of Bud Division 2) is not an essential gene but its deletion mutant proceeded through the cell cycle in the presence of microtubule-destabilizing drugs, thereby inducing a sharp decrease in viability. In addition, overexpression of Mps1p caused partial mitotic arrest in ibd2Δ as well as in bub2Δ, suggesting that IBD2 encodes a novel component of the spindle checkpoint downstream of MPS1. Overexpression of Ibd2p induced mitotic arrest with increased levels of Clb2p in wild type and mad2Δ, but not in deletion mutants of BUB2 and BFA1. Pds1p was also stabilized by the overexpression of Ibd2p in wild-type cells. The mitotic arrest defects observed in ibd2Δ in the presence of nocodazole were restored by additional copies of BUB2, BFA1, and CDC5, whereas an extra copy of IBD2 could not rescue the mitotic arrest defects of bub2Δ and bfa1Δ. The mitotic arrest defects of ibd2Δ were not recovered by MAD2, or vice versa. Analysis of the double mutant combinations ibd2Δmad2Δ, ibd2Δbub2Δ, and ibd2Δdyn1Δ showed that IBD2 belongs to the BUB2 epistasis group. Taken together, these data demonstrate that IBD2 encodes a novel component of the BUB2-dependent spindle checkpoint pathway that functions upstream of BUB2 and BFA1.


1996 ◽  
Vol 16 (12) ◽  
pp. 6775-6782 ◽  
Author(s):  
C F Hardy ◽  
A Pautz

DNA replication initiates from specific chromosomal sites called origins, and in the budding yeast Saccharomyces cerevisiae these sites are occupied by the origin recognition complex (ORC). Dbf4p is proposed to play a role in targeting the G1/S kinase Cdc7p to initiation complexes late in G1. We report that Dbf4p may also recruit Cdc5p to origin complexes. Cdc5p is a member of the Polo family of kinases that is required for the completion of mitosis. Cdc5p and Cdc7p each interact with a distinct domain of Dbf4p. cdc5-1 mutants have a plasmid maintenance defect that can be suppressed by the addition of multiple origins. cdc5-1 orc2-1 double mutants are synthetically lethal. Levels of Cdc5p were found to be cell cycle regulated and peaked in G2/M. These results suggest a role for Cdc5p and possibly Polo-like kinases at origin complexes.


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.


2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Bouchra Qaddouri ◽  
Abdelkarim Guaadaoui ◽  
Ahmed Bellirou ◽  
Abdellah Hamal ◽  
Ahmed Melhaoui ◽  
...  

The budding yeastSaccharomyces cerevisiaeis a valuable system to study cell-cycle regulation, which is defective in cancer cells. Due to the highly conserved nature of the cell-cycle machinery between yeast and humans, yeast studies are directly relevant to anticancer-drug discovery. The budding yeast is also an excellent model system for identifying and studying antifungal compounds because of the functional conservation of fungal genes. Moreover, yeast studies have also contributed greatly to our understanding of the biological targets and modes of action of bioactive compounds. Understanding the mechanism of action of clinically relevant compounds is essential for the design of improved second-generation molecules. Here we describe our methodology for screening a library of plant-derived natural products in yeast in order to identify and characterize new compounds with anti-proliferative properties.


2018 ◽  
Vol 29 (22) ◽  
pp. 2644-2655 ◽  
Author(s):  
Christina M. Kelliher ◽  
Matthew W. Foster ◽  
Francis C. Motta ◽  
Anastasia Deckard ◽  
Erik J. Soderblom ◽  
...  

In the budding yeast Saccharomyces cerevisiae, transcription factors (TFs) regulate the periodic expression of many genes during the cell cycle, including gene products required for progression through cell-cycle events. Experimental evidence coupled with quantitative models suggests that a network of interconnected TFs is capable of regulating periodic genes over the cell cycle. Importantly, these dynamical models were built on transcriptomics data and assumed that TF protein levels and activity are directly correlated with mRNA abundance. To ask whether TF transcripts match protein expression levels as cells progress through the cell cycle, we applied a multiplexed targeted mass spectrometry approach (parallel reaction monitoring) to synchronized populations of cells. We found that protein expression of many TFs and cell-cycle regulators closely followed their respective mRNA transcript dynamics in cycling wild-type cells. Discordant mRNA/protein expression dynamics was also observed for a subset of cell-cycle TFs and for proteins targeted for degradation by E3 ubiquitin ligase complexes such as SCF (Skp1/Cul1/F-box) and APC/C (anaphase-promoting complex/cyclosome). We further profiled mutant cells lacking B-type cyclin/CDK activity ( clb1-6) where oscillations in ubiquitin ligase activity, cyclin/CDKs, and cell-cycle progression are halted. We found that a number of proteins were no longer periodically degraded in clb1-6 mutants compared with wild type, highlighting the importance of posttranscriptional regulation. Finally, the TF complexes responsible for activating G1/S transcription (SBF and MBF) were more constitutively expressed at the protein level than at periodic mRNA expression levels in both wild-type and mutant cells. This comprehensive investigation of cell-cycle regulators reveals that multiple layers of regulation (transcription, protein stability, and proteasome targeting) affect protein expression dynamics during the cell cycle.


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