scholarly journals IBD2 Encodes a Novel Component of the Bub2p-Dependent Spindle Checkpoint in the Budding Yeast Saccharomyces cerevisiae

Genetics ◽  
2002 ◽  
Vol 161 (2) ◽  
pp. 595-609
Author(s):  
Hyung-Seo Hwang ◽  
Kiwon Song
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Budding Yeast ◽  
Essential Gene ◽  
Spindle Checkpoint ◽  
Mitotic Arrest ◽  
Mitotic Exit ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Checkpoint Pathway

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.

scholarly journals Depletion of H2A-H2B Dimers in Saccharomyces cerevisiae Triggers Meiotic Arrest by Reducing IME1 Expression and Activating the BUB2-Dependen Branch of the Spindle Checkpoint

Genetics ◽  
2003 ◽  
Vol 164 (4) ◽  
pp. 1333-1344
Author(s):  
Sean E Hanlon ◽  
David N Norris ◽  
Andrew K Vershon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spindle Checkpoint ◽  
The Other ◽  
Histone H2a ◽  
Wild Type ◽  
Meiotic Arrest ◽  
Yeast Saccharomyces Cerevisiae ◽  
Chromosomal Alterations ◽  
Checkpoint Pathway ◽  
Failure To Progress

Abstract In the yeast Saccharomyces cerevisiae, diploid strains carrying homozygous hta1-htb1Δ mutations express histone H2A-H2B dimers at a lower level than do wild-type cells. Although this mutation has only minor effects on mitotic growth, it causes an arrest in sporulation prior to the first meiotic division. In this report, we show that the hta1-htb1Δ mutant exhibits reduced expression of early and middle-sporulation-specific genes and that the meiotic arrest of the hta1-htb1Δ mutant can be partially bypassed by overexpression of IME1. Additionally, deletions of BUB2 or BFA1, components of one branch of the spindle checkpoint pathway, bypass the meiotic arrest. Mutations in the other branch of the pathway or in the pachytene checkpoint are unable to suppress the meiotic block. These observations indicate that depletion of the H2A-H2B dimer blocks sporulation by at least two mechanisms: disruption of the expression of meiotic regulatory genes and activation of the spindle checkpoint. Our results show that the failure to progress through the meiotic pathway is not the result of global chromosomal alterations but that specific aspects of meiosis are sensitive to depletion of the H2A-H2B dimer.

scholarly journals Layers of regulation of cell-cycle gene expression in the budding yeast Saccharomyces cerevisiae

2018 ◽  
Vol 29 (22) ◽  
pp. 2644-2655 ◽  
Author(s):  
Christina M. Kelliher ◽  
Matthew W. Foster ◽  
Francis C. Motta ◽  
Anastasia Deckard ◽  
Erik J. Soderblom ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Protein Expression ◽  
Ubiquitin Ligase ◽  
Budding Yeast ◽  
Cell Cycle Regulators ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Expression Levels ◽  
Mutant Cells

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.

scholarly journals Reduced Mad2 expression keeps relaxed kinetochores from arresting budding yeast in mitosis

2011 ◽  
Vol 22 (14) ◽  
pp. 2448-2457 ◽  
Author(s):  
Erin L. Barnhart ◽  
Russell K. Dorer ◽  
Andrew W. Murray ◽  
Scott C. Schuyler
Keyword(s):  
Chromosome Segregation ◽  
Budding Yeast ◽  
Spindle Checkpoint ◽  
Chromosome Loss ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Diploid Cells ◽  
Antimicrotubule Drugs

Chromosome segregation depends on the spindle checkpoint, which delays anaphase until all chromosomes have bound microtubules and have been placed under tension. The Mad1–Mad2 complex is an essential component of the checkpoint. We studied the consequences of removing one copy of MAD2 in diploid cells of the budding yeast, Saccharomyces cerevisiae. Compared to MAD2/MAD2 cells, MAD2/mad2Δ heterozygotes show increased chromosome loss and have different responses to two insults that activate the spindle checkpoint: MAD2/mad2Δ cells respond normally to antimicrotubule drugs but cannot respond to chromosomes that lack tension between sister chromatids. In MAD2/mad2Δ cells with normal sister chromatid cohesion, removing one copy of MAD1 restores the checkpoint and returns chromosome loss to wild-type levels. We conclude that cells need the normal Mad2:Mad1 ratio to respond to chromosomes that are not under tension.

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
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Monoclonal Antibody ◽  
Plasma Membrane ◽  
Key Words ◽  
Budding Yeast ◽  
Yeast Saccharomyces Cerevisiae ◽  
Double Labeling ◽  
Interacting Protein ◽  
Cytoplasmic Microtubules

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.

scholarly journals Relationship of actin and tubulin distribution to bud growth in wild-type and morphogenetic-mutant Saccharomyces cerevisiae.

1984 ◽  
Vol 98 (3) ◽  
pp. 934-945 ◽  
Author(s):  
A E Adams ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Spindle Pole Body ◽  
Neck Region ◽  
Spindle Pole ◽  
Wild Type ◽  
Active Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
The One ◽  
Relationship Of

The distribution of actin in wild-type cells and in morphogenetic mutants of the budding yeast Saccharomyces cerevisiae was explored by staining cells with fluorochrome-labeled phallotoxins after fixing and permeabilizing the cells by several methods. The actin appeared to be localized in a set of cortical spots or patches, as well as in a network of cytoplasmic fibers. Bundles of filaments that may possibly correspond to the fibers visualized by fluorescence were observed with the electron microscope. The putative actin spots were concentrated in small and medium-sized buds and at what were apparently the sites of incipient bud formation on unbudded cells, whereas the putative actin fibers were generally oriented along the long axes of the mother-bud pairs. In several morphogenetic mutants that form multiple, abnormally elongated buds, the actin patches were conspicuously clustered at the tips of most buds, and actin fibers were clearly oriented along the long axes of the buds. There was a strong correlation between the occurrence of active growth at particular bud tips and clustering of actin spots at those same tips. Near the end of the cell cycle in wild-type cells, actin appeared to concentrate (as a cluster of spots or a band) in the neck region connecting the mother cell to its bud. Observations made using indirect immunofluorescence with a monoclonal anti-yeast-tubulin antibody on the morphogenetic mutant cdc4 (which forms multiple, abnormally elongated buds while the nuclear cycle is arrested) revealed the surprising occurrence of multiple bundles of cytoplasmic microtubules emanating from the one duplicated spindle-pole body per cell. It seems that most or all of the buds contain one or more of these bundles of microtubules, which often can be seen to extend to the very tips of the buds. These observations are consistent with the hypotheses that actin, tubulin, or both may be involved in the polarization of growth and localization of cell-wall deposition that occurs during the yeast cell cycle.

scholarly journals The yeast nuclear pore complex functionally interacts with components of the spindle assembly checkpoint

2002 ◽  
Vol 159 (5) ◽  
pp. 807-819 ◽  
Author(s):  
Tatiana Iouk ◽  
Oliver Kerscher ◽  
Robert J. Scott ◽  
Munira A. Basrai ◽  
Richard W. Wozniak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Genetic Analysis ◽  
Nuclear Pore Complex ◽  
Spindle Assembly Checkpoint ◽  
Spindle Checkpoint ◽  
Spindle Assembly ◽  
Nuclear Pore ◽  
Yeast Saccharomyces Cerevisiae ◽  
Functional Link

Aphysical and functional link between the nuclear pore complex (NPC) and the spindle checkpoint machinery has been established in the yeast Saccharomyces cerevisiae. We show that two proteins required for the execution of the spindle checkpoint, Mad1p and Mad2p, reside predominantly at the NPC throughout the cell cycle. There they are associated with a subcomplex of nucleoporins containing Nup53p, Nup170p, and Nup157p. The association of the Mad1p–Mad2p complex with the NPC requires Mad1p and is mediated in part by Nup53p. On activation of the spindle checkpoint, we detect changes in the interactions between these proteins, including the release of Mad2p (but not Mad1p) from the NPC and the accumulation of Mad2p at kinetochores. Accompanying these events is the Nup53p-dependent hyperphosphorylation of Mad1p. On the basis of these results and genetic analysis of double mutants, we propose a model in which Mad1p bound to a Nup53p-containing complex sequesters Mad2p at the NPC until its release by activation of the spindle checkpoint. Furthermore, we show that the association of Mad1p with the NPC is not passive and that it plays a role in nuclear transport.

Sign in / Sign up

Export Citation Format

Share Document