scholarly journals Chromosome condensation and sister chromatid pairing in budding yeast.

1994 ◽  
Vol 125 (3) ◽  
pp. 517-530 ◽  
Author(s):  
V Guacci ◽  
E Hogan ◽  
D Koshland
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Repetitive Sequences ◽  
Cell Cycle Regulators ◽  
Mitotic Chromosomes ◽  
Rdna Cluster ◽  
Unique Region ◽  
Artificial Chromosomes ◽  
Fish Method ◽  
Sister Chromatids

We have developed a fluorescent in situ hybridization (FISH) method to examine the structure of both natural chromosomes and small artificial chromosomes during the mitotic cycle of budding yeast. Our results suggest that the pairing of sister chromatids: (a) occurs near the centromere and at multiple places along the chromosome arm as has been observed in other eukaryotic cells; (b) is maintained in the absence of catenation between sister DNA molecules; and (c) is independent of large blocks of repetitive DNA commonly associated with heterochromatin. Condensation of a unique region of chromosome XVI and the highly repetitive ribosomal DNA (rDNA) cluster from chromosome XII were also examined in budding yeast. Interphase chromosomes were condensed 80-fold relative to B form DNA, similar to what has been observed in other eukaryotes, suggesting that the structure of interphase chromosomes may be conserved among eukaryotes. While additional condensation of budding yeast chromosomes were observed during mitosis, the level of condensation was less than that observed for human mitotic chromosomes. At most stages of the cell cycle, both unique and repetitive sequences were either condensed or decondensed. However, in cells arrested in late mitosis (M) by a cdc15 mutation, the unique DNA appeared decondensed while the repetitive rDNA region appeared condensed, suggesting that the condensation state of separate regions of the genome may be regulated differently. The ability to monitor the pairing and condensation of sister chromatids in budding yeast should facilitate the molecular analysis of these processes as well as provide two new landmarks for evaluating the function of important cell cycle regulators like p34 kinases and cyclins. Finally our FISH method provides a new tool to analyze centromeres, telomeres, and gene expression in budding yeast.

scholarly journals Cell Cycle-dependent Expression and Nucleolar Localization of hCAP-H

2001 ◽  
Vol 12 (11) ◽  
pp. 3527-3537 ◽  
Author(s):  
Olga A. Cabello ◽  
Elena Eliseeva ◽  
WeiGong He ◽  
Hagop Youssoufian ◽  
Sharon E. Plon ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Histone H3 ◽  
Chromosome Condensation ◽  
Nucleolar Localization ◽  
Mitotic Chromosomes ◽  
Proliferating Cells ◽  
Protein Levels ◽  
Sister Chromatids ◽  
H3 Phosphorylation ◽  
Histone H3 Phosphorylation

Condensin is a conserved 13S heteropentamer composed of two nonidentical structural maintenance of chromosome (SMC) family proteins, in Xenopus XCAP-C and XCAP-E, and three regulatory subunits, XCAP-D2, XCAP-G, and XCAP-H. Both biochemical and genetic analyses have demonstrated an essential role for the 13S condensin complex in mitotic chromosome condensation. Further, a potential requirement for condensin in completion of chromatid arm separation in early anaphase is demonstrated by the mutational phenotypes of the Drosophila homologues ofXCAP-H, barren and XCAP-C,DmSMC4. In this study we have investigated the expression and subcellular distribution of hCAP-H, the human homolog of XCAP-H, in order to better understand its cellular functions. Transcription of hCAP-H was restricted to proliferating cells with highest expression during the G2 phase of the cell cycle. In contrast, cellular hCAP-H protein levels were constant throughout the cell cycle. hCAP-H was found to be associated with mitotic chromosomes exhibiting a nonuniform but symmetric distribution along sister chromatids. The symmetry of hCAP-H association with sister chromatids suggests that there are sequence-dependent domains of condensin aggregation. During interphase hCAP-H, -C, and -E, have distinct punctate nucleolar localization, suggesting that condensin may associate with and modulate the conformation and function of rDNA. hCAP-H association with condensed chromatin was not observed in the early phase of chromosome condensation when histone H3 phosphorylation has already taken place. This finding is consistent with the hypothesis that histone H3 phosphorylation precedes condensin-mediated condensation.

scholarly journals Identifying Novel Cell Cycle Regulators in Budding Yeast

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Tesia Stephenson ◽  
Paula Fearon ◽  
Orna Cohen‐Fix
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Cell Cycle Regulators

scholarly journals Swm1/Apc13 Is an Evolutionarily Conserved Subunit of the Anaphase-Promoting Complex Stabilizing the Association of Cdc16 and Cdc27

2004 ◽  
Vol 24 (8) ◽  
pp. 3562-3576 ◽  
Author(s):  
Martin Schwickart ◽  
Jan Havlis ◽  
Bianca Habermann ◽  
Aliona Bogdanova ◽  
Alain Camasses ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Small Subunit ◽  
Cell Cycle Regulators ◽  
Anaphase Promoting Complex ◽  
Ubiquitin Ligase Activity ◽  
Evolutionarily Conserved ◽  
Stable Association

ABSTRACT The anaphase-promoting complex (APC/C) is a large ubiquitin-protein ligase which controls progression through anaphase by triggering the degradation of cell cycle regulators such as securin and B-type cyclins. The APC/C is an unusually complex ligase containing at least 10 different, evolutionarily conserved components. In contrast to APC/C's role in cell cycle regulation little is known about the functions of individual subunits and how they might interact with each other. Here, we have analyzed Swm1/Apc13, a small subunit recently identified in the budding yeast complex. Database searches revealed proteins related to Swm1/Apc13 in various organisms including humans. Both the human and the fission yeast homologues are associated with APC/C subunits, and they complement the phenotype of an SWM1 deletion mutant of budding yeast. Swm1/Apc13 promotes the stable association with the APC/C of the essential subunits Cdc16 and Cdc27. Accordingly, Swm1/Apc13 is required for ubiquitin ligase activity in vitro and for the timely execution of APC/C-dependent cell cycle events in vivo.

The Drosophila melanogaster dodecasatellite sequence is closely linked to the centromere and can form connections between sister chromatids during mitosis

1993 ◽  
Vol 105 (1) ◽  
pp. 41-50 ◽  
Author(s):  
M. Carmena ◽  
J.P. Abad ◽  
A. Villasante ◽  
C. Gonzalez
Keyword(s):  
Cell Cycle ◽  
Drosophila Melanogaster ◽  
In Situ Hybridisation ◽  
Polytene Chromosomes ◽  
Colchicine Treatment ◽  
Dependent Manner ◽  
Fluorescence In Situ Hybridisation ◽  
Mitotic Chromosomes ◽  
Sister Chromatids ◽  
Diploid Cells

We have used fluorescence in situ hybridisation to wild-type and rearranged mitotic chromosomes to map the Drosophila melanogaster dodecasatellite sequence. It is located at a unique site, within the pericentric heterochromatin of the right arm of the third chromosome, closely linked to the primary constriction. In polytene chromosomes, dodecasatellite is found as one or a few dots in the central region of the chromocentre. In untreated diploid cells, dodecasatellite sequences are found as one or two dots throughout the cell cycle. This distribution can be altered in a cell cycle-dependent manner in two ways. Firstly, in interphase cells, hypotonic shock promotes the decondensation of the genomic region containing this satellite, resulting in a string-like structure. Secondly, some of the precociously separated sister chromatids produced by colchicine treatment show dodecasatellite within the intervening space connecting the main dodecasatellite signals of each chromatid. The distribution of dodecasatellite seems to be rather constant between individuals of the same species, as indicated by the lack of any detectable variations in its pattern amongst individuals from six geographically distant strains of D. melanogaster. On the other hand, the distribution of dodecasatellite shows a remarkable degree of variation amongst closely related species of the melanogaster subgroup ranging from a non-detectable signal in Drosophila yakuba and Drosophila teissieri, to staining in the X, second and third chromososomes of Drosophila mauritiana.

Kinetochore localisation and phosphorylation of the mitotic checkpoint components Bub1 and BubR1 are differentially regulated by spindle events in human cells

2001 ◽  
Vol 114 (24) ◽  
pp. 4385-4395 ◽  
Author(s):  
Stephen S. Taylor ◽  
Deema Hussein ◽  
Yunmei Wang ◽  
Sarah Elderkin ◽  
Christopher J. Morrow
Keyword(s):  
Cell Cycle ◽  
Protein Kinases ◽  
Budding Yeast ◽  
Spindle Assembly ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Cell Cycle Regulators ◽  
Yeast Gene ◽  
Microtubule Attachment ◽  
Spindle Dynamics

BUB1 is a budding yeast gene required to ensure that progression through mitosis is coupled to correct spindle assembly. Two related human protein kinases, Bub1 and BubR1, both localise to kinetochores during mitosis, suggesting that they play a role in delaying anaphase until all chromosomes achieve correct, bipolar attachment to the spindle. However, how the activities of Bub1 and BubR1 are regulated by spindle events and how their activities regulate downstream cell cycle events is not known.To investigate how spindle events regulate Bub1 and BubR1, we characterised their relative localisations during mitosis in the presence and absence of microtubule toxins. In prometaphase cells, both kinases colocalise to the same domain of the kinetochore. However, whereas the localisation of BubR1 at sister kinetochores is symmetrical, localisation of Bub1 is often asymmetrical. This asymmetry is dependent on microtubule attachment, and the kinetochore exhibiting weaker Bub1 staining is typically closer to the nearest spindle pole. In addition, a 30 minute nocodazole treatment dramatically increases the amount of Bub1 localising to kinetochores but has little effect on BubR1. Furthermore, Bub1 levels increase at metaphase kinetochores following loss of tension caused by taxol treatment. Thus, these observations suggest that Bub1 localisation is sensitive to changes in both tension and microtubule attachment.Consistent with this, we also show that Bub1 is rapidly phosphorylated following brief treatments with nocodazole or taxol. In contrast, BubR1 is phosphorylated in the absence of microtubule toxins, and spindle damage has little additional effect. Although these observations indicate that Bub1 and BubR1 respond differently to spindle dynamics, they are part of a common complex during mitosis. We suggest therefore that Bub1 and BubR1 may integrate different ‘spindle assembly signals’ into a single signal which can then be interpreted by downstream cell cycle regulators.

scholarly journals Dilution and titration of cell-cycle regulators may control cell size in budding yeast

2018 ◽  
Vol 14 (10) ◽  
pp. e1006548 ◽  
Author(s):  
Frank S. Heldt ◽  
Reece Lunstone ◽  
John J. Tyson ◽  
Béla Novák
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Budding Yeast ◽  
Control Cell ◽  
Cell Cycle Regulators

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 Tripartite chromatin localization of budding yeast Shugoshin involves higher-ordered architecture of mitotic chromosomes

2018 ◽  
Author(s):  
Xiexiong Deng ◽  
Min-Hao Kuo
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Mitotic Chromosome ◽  
Budding Yeast ◽  
Histone H3 ◽  
Spindle Assembly ◽  
Mitotic Spindles ◽  
Mitotic Chromosomes ◽  
Chromatin Architecture ◽  
Sister Chromatids ◽  
Segregation Of Chromosomes

ABSTRACTThe spindle assembly checkpoint (SAC) is key to faithful segregation of chromosomes. One requirement that satisfies SAC is appropriate tension between sister chromatids at the metaphase-anaphase juncture. Proper tension generated by poleward pulling of mitotic spindles signals biorientation of the underlying chromosome. In the budding yeast, the tension status is monitored by the conserved Shugoshin protein, Sgo1p, and the tension sensing motif (TSM) of histone H3. ChIP-seq reveals a unique TSM-dependent, tripartite domain of Sgo1p in each mitotic chromosome. This domain consists of one centromeric and two flanking peaks 3 – 4 kb away, and is present exclusively in mitosis. Strikingly, this trident motif coincides with cohesin localization, but only at the centromere and the two immediate adjacent loci, despite that cohesin is enriched at numerous regions throughout mitotic chromosomes. The TSM-Sgo1p-cohesin triad is at the center stage of higher-ordered chromatin architecture for error-free segregation.

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