The Effects of Ploidy upon Cell Cycle Dependent Changes in X-Ray Sensitivity of Saccharomyces cerevisiae

1973 ◽  
Vol 55 (3) ◽  
pp. 501 ◽  
Author(s):  
Elia Nunes de Langguth ◽  
Carl A. Beam
1987 ◽  
Vol 7 (12) ◽  
pp. 4204-4210
Author(s):  
M A Osley ◽  
D Lycan

Using a Saccharomyces cerevisiae strain containing an integrated copy of an H2A-lacZ fusion gene, we screened for mutants which overexpressed beta-galactosidase as a way to identify genes which regulate transcription of the histone genes. Five recessive mutants with this phenotype were shown to contain altered regulatory genes because they had lost repression of HTA1 transcription which occurs upon inhibition of chromosome replication (D. E. Lycan, M. A. Osley, and L. Hereford, Mol. Cell. Biol. 7:614-621, 1987). Periodic transcription was affected in the mutants as well, since the HTA1 gene was transcribed during the G1 and G2 phases of the cell cycle, periods in the cell cycle when this gene is normally not expressed. A similar loss of cell cycle-dependent transcription was noted for two of the three remaining histone loci, while the HO and CDC9 genes continued to be expressed periodically. Using isolated promoter elements inserted into a heterologous cycl-lacZ fusion gene, we demonstrated that the mutations fell in genes which acted through a negative site in the TRT1 H2A-H2B promoter.


2016 ◽  
Vol 214 (6) ◽  
pp. 691-703 ◽  
Author(s):  
Dante Lepore ◽  
Olya Spassibojko ◽  
Gabrielle Pinto ◽  
Ruth N. Collins

Intracellular trafficking is an essential and conserved eukaryotic process. Rab GTPases are a family of proteins that regulate and provide specificity for discrete membrane trafficking steps by harnessing a nucleotide-bound cycle. Global proteomic screens have revealed many Rab GTPases as phosphoproteins, but the effects of this modification are not well understood. Using the Saccharomyces cerevisiae Rab GTPase Sec4p as a model, we have found that phosphorylation negatively regulates Sec4p function by disrupting the interaction with the exocyst complex via Sec15p. We demonstrate that phosphorylation of Sec4p is a cell cycle–dependent process associated with cytokinesis. Through a genomic kinase screen, we have also identified the polo-like kinase Cdc5p as a positive regulator of Sec4p phosphorylation. Sec4p spatially and temporally localizes with Cdc5p exclusively when Sec4p phosphorylation levels peak during the cell cycle, indicating Sec4p is a direct Cdc5p substrate. Our data suggest the physiological relevance of Sec4p phosphorylation is to facilitate the coordination of membrane-trafficking events during cytokinesis.


2009 ◽  
Vol 29 (18) ◽  
pp. 4891-4905 ◽  
Author(s):  
Santhi Pondugula ◽  
Daniel W. Neef ◽  
Warren P. Voth ◽  
Russell P. Darst ◽  
Archana Dhasarathy ◽  
...  

ABSTRACT Cells devote considerable resources to nutrient homeostasis, involving nutrient surveillance, acquisition, and storage at physiologically relevant concentrations. Many Saccharomyces cerevisiae transcripts coding for proteins with nutrient uptake functions exhibit peak periodic accumulation during M phase, indicating that an important aspect of nutrient homeostasis involves transcriptional regulation. Inorganic phosphate is a central macronutrient that we have previously shown oscillates inversely with mitotic activation of PHO5. The mechanism of this periodic cell cycle expression remains unknown. To date, only two sequence-specific activators, Pho4 and Pho2, were known to induce PHO5 transcription. We provide here evidence that Mcm1, a MADS-box protein, is essential for PHO5 mitotic activation. In addition, we found that cells simultaneously lacking the forkhead proteins, Fkh1 and Fkh2, exhibited a 2.5-fold decrease in PHO5 expression. The Mcm1-Fkh2 complex, first shown to transactivate genes within the CLB2 cluster that drive G2/M progression, also associated directly at the PHO5 promoter in a cell cycle-dependent manner in chromatin immunoprecipitation assays. Sds3, a component specific to the Rpd3L histone deacetylase complex, was also recruited to PHO5 in G1. These findings provide (i) further mechanistic insight into PHO5 mitotic activation, (ii) demonstrate that Mcm1-Fkh2 can function combinatorially with other activators to yield late M/G1 induction, and (iii) couple the mitotic cell cycle progression machinery to cellular phosphate homeostasis.


1984 ◽  
Vol 4 (12) ◽  
pp. 2858-2864 ◽  
Author(s):  
R K Storms ◽  
R W Ord ◽  
M T Greenwood ◽  
B Mirdamadi ◽  
F K Chu ◽  
...  

Synchronous populations of Saccharomyces cerevisiae cells, generated by two independent methods, have been used to show that thymidylate synthase, in contrast to the vast majority of cellular proteins thus far examined, fluctuates periodically during the S. cerevisiae cell cycle. The enzyme, as assayed by two different methods, accumulated during S period and peaked in mid to late S phase, and then its level dropped. These observations suggest that both periodic synthesis and the instability of the enzyme contribute to the activity profile seen during the cell cycle. Accumulation of thymidylate synthase is determined at the level of its transcript, with synthase-specific mRNA levels increasing at least 10-fold to peak near the beginning of S period and then falling dramatically to basal levels after the onset of DNA synthesis. This mRNA peak coincided with the time during the cell cycle when thymidylate synthase levels were increasing maximally and immediately preceded the peak of DNA synthesis, for which the enzyme provides precursor dTMP.


1991 ◽  
Vol 11 (1) ◽  
pp. 329-337 ◽  
Author(s):  
E M McIntosh ◽  
T Atkinson ◽  
R K Storms ◽  
M Smith

Comparison of the 5'-flanking regions of several cell cycle-regulated DNA replication genes of Saccharomyces cerevisiae has revealed the presence of a common sequence, 5'-ACGCGT-3', which is upstream and proximal to mapped transcription initiation sites. This sequence, which is the cleavage site for the restriction endonuclease MluI, is present twice in the upstream region of the yeast thymidylate synthase gene TMP1. Previous studies have implicated these MluI sites as critical components in the cell cycle-dependent transcription of TMP1. In this study, we examined more closely the importance of the ACGCGT sequences for the transcription of this gene. Using site-directed mutagenesis in combination with deletion analysis and subcloning experiments, we found that (i) while both of the TMP1 MluI sites contribute to the total transcription of this gene, the distal site is predominant and (ii) the 9-bp sequence ACGCGTTAA encompassing the distal MluI site exhibits properties of a cell cycle-stage dependent upstream activation sequence element. The results of this study support the notion that the ACGCGT sequence is an integral component of a transcription system which coordinates the cell cycle-dependent expression of DNA replication genes in S. cerevisiae.


1989 ◽  
Vol 35 (1) ◽  
pp. 59-63 ◽  
Author(s):  
ISAO UNO ◽  
YOSHIKAZU OHYA ◽  
YASUHIRO ANRAKU ◽  
TATSUO ISHIKAWA

2008 ◽  
Vol 162 (2) ◽  
pp. 248-259 ◽  
Author(s):  
Sophie Bachellier-Bassi ◽  
Olivier Gadal ◽  
Gaëlle Bourout ◽  
Ulf Nehrbass

1973 ◽  
Vol 53 (2) ◽  
pp. 226 ◽  
Author(s):  
Elia Nunes de Langguth ◽  
Carl A. Beam

1988 ◽  
Vol 8 (11) ◽  
pp. 4616-4624
Author(s):  
E M McIntosh ◽  
R W Ord ◽  
R K Storms

We have previously shown that transcript levels expressed from the yeast TMP1 gene fluctuate periodically during the yeast cell cycle. However, it was not known whether periodic expression resulted from a regulatory mechanism acting at the level of transcription or a regulatory mechanism acting at the level of cell cycle stage-dependent changes in the stability of the TMP1 transcript. In this report we now show that the periodic expression of TMP1 transcript is primarily controlled at the level of its transcription by sequences which are upstream of its transcription initiation sites. We also localized the upstream sequences necessary for periodic transcription to a 150-base-pair region and show that this region encodes an element(s) with the properties of a periodic upstream activating sequence. The regulatory region defined in this study apparently does not contain consensus sequences similar to those reported for the cell cycle-regulated HO endonuclease or for the histone H2A and H2B genes of Saccharomyces cerevisiae.


1984 ◽  
Vol 4 (12) ◽  
pp. 2858-2864
Author(s):  
R K Storms ◽  
R W Ord ◽  
M T Greenwood ◽  
B Mirdamadi ◽  
F K Chu ◽  
...  

Synchronous populations of Saccharomyces cerevisiae cells, generated by two independent methods, have been used to show that thymidylate synthase, in contrast to the vast majority of cellular proteins thus far examined, fluctuates periodically during the S. cerevisiae cell cycle. The enzyme, as assayed by two different methods, accumulated during S period and peaked in mid to late S phase, and then its level dropped. These observations suggest that both periodic synthesis and the instability of the enzyme contribute to the activity profile seen during the cell cycle. Accumulation of thymidylate synthase is determined at the level of its transcript, with synthase-specific mRNA levels increasing at least 10-fold to peak near the beginning of S period and then falling dramatically to basal levels after the onset of DNA synthesis. This mRNA peak coincided with the time during the cell cycle when thymidylate synthase levels were increasing maximally and immediately preceded the peak of DNA synthesis, for which the enzyme provides precursor dTMP.


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