scholarly journals The G1/S Cyclin Cig2p during Meiosis in Fission Yeast

2002 ◽  
Vol 13 (6) ◽  
pp. 2080-2090 ◽  
Author(s):  
Annie Borgne ◽  
Hiroshi Murakami ◽  
José Ayté ◽  
Paul Nurse
Keyword(s):  
Fission Yeast ◽  
S Phase ◽  
Start Site ◽  
Meiotic Cell ◽  
Transcription Start ◽  
Cell Cycles ◽  
Cyclin Dependent Kinases ◽  
Mitotic Cyclin ◽  
Specific Regulation

Cyclin-dependent kinases (CDKs) are important for both mitotic and meiotic cell cycles. In fission yeast, the major CDK, Cdc2p is involved in premeiotic DNA replication and in meiosis II. One of its partners, the mitotic cyclin Cdc13p is known to be required for meiosis, whereas there are no studies on the G1/S cyclin Cig2p. In this article, we have studied the regulation of the Cdc2p/Cdc13p and Cdc2p/Cig2p complexes during synchronous meiosis. We observed that Cdc2p/Cig2p kinase is activated in an unexpected biphasic manner, first at onset of premeiotic S phase and again during meiotic nuclear divisions. The role of Cig2p during meiosis was investigated usingcig2-deleted strains that exhibit delays in onset of both S phase and meiotic divisions as well as an inefficient completion of MII. Furthermore, analysis of cig2 transcripts revealed a meiosis-specific regulation of cig2expression during MI/MII dependent upon the Mei4p transcription factor leading to a different transcription start site at this stage of meiosis.

Differential function and expression of Saccharomyces cerevisiae B-type cyclins in mitosis and meiosis

1993 ◽  
Vol 13 (4) ◽  
pp. 2113-2125
Author(s):  
N Grandin ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Kinase Activity ◽  
Mitotic Cell ◽  
S Phase ◽  
Mitotic Cell Cycle ◽  
Meiotic Cell ◽  
Cell Cycles ◽  
M Phase ◽  
Mitotic Cyclin

We have studied the patterns of expression of four B-type cyclins (Clbs), Clb1, Clb2, Clb3, and Clb4, and their ability to activate p34cdc28 during the mitotic and meiotic cell cycles of Saccharomyces cerevisiae. During the mitotic cell cycle, Clb3 and Clb4 were expressed and induced a kinase activity in association with p34cdc28 from early S phase up to mitosis. On the other hand, Clb1 and Clb2 were expressed and activated p34cdc28 later in the mitotic cell cycle, starting in late S phase and continuing up to mitosis. The pattern of expression of Clb3 and Clb4 suggests a possible role in the regulation of DNA replication as well as mitosis. Clb1 and Clb2, whose pattern of expression is similar to that of other known Clbs, are likely to have a role predominantly in the regulation of M phase. During the meiotic cell cycle, Clb1, Clb3, and Clb4 were expressed and induced a p34cdc28-associated kinase activity just before the first meiotic division. The fact that Clb3 and Clb4 were not synthesized earlier, in S phase, suggests that these cyclins, which probably have a role in S phase during the mitotic cell cycle, are not implicated in premeiotic S phase. Clb2, the primary mitotic cyclin in S. cerevisiae, was not detectable during meiosis. Sporulation experiments on strains deleted for one, two, or three Clbs indicate, in agreement with the biochemical data, that Clb1 is the primary cyclin for the regulation of meiosis, while Clb2 is not involved at all.

scholarly journals Differential function and expression of Saccharomyces cerevisiae B-type cyclins in mitosis and meiosis.

1993 ◽  
Vol 13 (4) ◽  
pp. 2113-2125 ◽  
Author(s):  
N Grandin ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Kinase Activity ◽  
Mitotic Cell ◽  
S Phase ◽  
Mitotic Cell Cycle ◽  
Meiotic Cell ◽  
Cell Cycles ◽  
M Phase ◽  
Mitotic Cyclin

We have studied the patterns of expression of four B-type cyclins (Clbs), Clb1, Clb2, Clb3, and Clb4, and their ability to activate p34cdc28 during the mitotic and meiotic cell cycles of Saccharomyces cerevisiae. During the mitotic cell cycle, Clb3 and Clb4 were expressed and induced a kinase activity in association with p34cdc28 from early S phase up to mitosis. On the other hand, Clb1 and Clb2 were expressed and activated p34cdc28 later in the mitotic cell cycle, starting in late S phase and continuing up to mitosis. The pattern of expression of Clb3 and Clb4 suggests a possible role in the regulation of DNA replication as well as mitosis. Clb1 and Clb2, whose pattern of expression is similar to that of other known Clbs, are likely to have a role predominantly in the regulation of M phase. During the meiotic cell cycle, Clb1, Clb3, and Clb4 were expressed and induced a p34cdc28-associated kinase activity just before the first meiotic division. The fact that Clb3 and Clb4 were not synthesized earlier, in S phase, suggests that these cyclins, which probably have a role in S phase during the mitotic cell cycle, are not implicated in premeiotic S phase. Clb2, the primary mitotic cyclin in S. cerevisiae, was not detectable during meiosis. Sporulation experiments on strains deleted for one, two, or three Clbs indicate, in agreement with the biochemical data, that Clb1 is the primary cyclin for the regulation of meiosis, while Clb2 is not involved at all.

The Role of XPB/Ssl2 dsDNA Translocase Processivity in Transcription Start-site Scanning

2021 ◽  
pp. 166813
Author(s):  
Eric J. Tomko ◽  
Olivia Luyties ◽  
Jenna K. Rimel ◽  
Chi-Lin Tsai ◽  
Jill O. Fuss ◽  
...  
Keyword(s):  
Transcription Start Site ◽  
Start Site ◽  
Transcription Start

scholarly journals Computational modelling of chromosome re-replication in mutant strains of fission yeast

2020 ◽  
Author(s):  
Béla Novák ◽  
John J Tyson
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Computational Modelling ◽  
Mitotic Cell ◽  
Cyclin Dependent Kinase ◽  
Slow Increase ◽  
Cell Cycles ◽  
Mitotic Cyclin ◽  
The Mathematical Model ◽  
Insight Into

AbstractTypically cells replicate their genome only once per division cycle, but under some circumstances, both natural and unnatural, cells synthesize an overabundance of DNA, either in a disorganized fashion (‘over-replication’) or by a systematic doubling of chromosome number (‘endoreplication’). These variations on the theme of DNA replication and division have been studied in strains of fission yeast, Schizosaccharomyces pombe, carrying mutations that interfere with the function of mitotic cyclin-dependent kinase (Cdk1:Cdc13) without impeding the roles of DNA-replication licensing factor (Cdc18) and S-phase cyclin-dependent kinase (Cdk1:Cig2). Some of these mutations support endoreplication, and some over-replication. In this paper, we propose a dynamical model of the interactions among the proteins governing DNA replication and cell division in fission yeast. By computational simulations of the mathematical model, we account for the observed phenotypes of these re-replicating mutants, and by theoretical analysis of the dynamical system, we provide insight into the molecular distinctions between over-replicating and endoreplicating cells. In case of induced over-production of regulatory proteins, our model predicts that cells first switch from normal mitotic cell cycles to growth-controlled endoreplication, and ultimately to disorganized over-replication, parallel to the slow increase of protein to very high levels.

Cyclin Dependent Kinases and Regulation of the Fission Yeast Cell Cycle

1999 ◽  
Vol 380 (7-8) ◽  
pp. 729-733 ◽  
Author(s):  
P. Nurse
Keyword(s):  
Cell Cycle ◽  
Yeast Cell ◽  
Fission Yeast ◽  
S Phase ◽  
Yeast Cell Cycle ◽  
Cyclin Dependent Kinases ◽  
Fission Yeast Cell ◽  
Nutritional Deprivation ◽  
Orderly Fashion ◽  
A Cell

AbstractThe cyclin dependent kinases (CDKs), formed by complexes between Cdc2p and the B-cyclins Cig2p and Cdc13p, have a central role in regulating the fission yeast cell cycle and maintaining genomic stability. The CDK Cig2p/Cdc2p controls the onset of S-phase and the CDK Cdc13p/Cdc2p controls the onset of mitosis and ensures that there is only one S-phase in each cell. Cdc13p/Cdc2p can replace Cig2p/Cdc2p for the onset of S-phase, suggesting that the increasing activity of a single CDK during the cell cycle is sufficient to drive a cell in an orderly fashion into S-phase and into mitosis. If S-phase is incomplete, then inhibition of Cdc13p/Cdc2p prevents cells with unreplicated DNA from undergoing a catastrophic entry into mitosis. Control of CDK activity is also important to allow cells to exit the cell cycle and accumulate in G1 in response to nutritional deprivation and the presence of pheromone.

scholarly journals FIS activatesglnAp2 inEscherichia coli: role of a DNA bend centered at −55, upstream of the transcription start site

2006 ◽  
Vol 257 (1) ◽  
pp. 99-105 ◽  
Author(s):  
Yi-Xin Huo ◽  
Bei-Yan Nan ◽  
Cong-Hui You ◽  
Zhe-Xian Tian ◽  
Annie Kolb ◽  
...  
Keyword(s):  
Transcription Start Site ◽  
Inescherichia Coli ◽  
Start Site ◽  
Transcription Start

scholarly journals Fission yeast cell cycle mutants and the logic of eukaryotic cell cycle control

2020 ◽  
Vol 31 (26) ◽  
pp. 2871-2873
Author(s):  
Paul Nurse
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Fission Yeast ◽  
Cell Cycle Control ◽  
Eukaryotic Cell ◽  
S Phase ◽  
Cyclin Dependent Kinases ◽  
Starting Point ◽  
Rate Limiting ◽  
Working Out

Cell cycle mutants in the budding and fission yeasts have played critical roles in working out how the eukaryotic cell cycle operates and is controlled. The starting point was Lee Hartwell’s 1970s landmark papers describing the first cell division cycle (CDC) mutants in budding yeast. These mutants were blocked at different cell cycle stages and so were unable to complete the cell cycle, thus defining genes necessary for successful cell division. Inspired by Hartwell’s work, I isolated CDC mutants in the very distantly related fission yeast. This started a program of searches for mutants in fission yeast that revealed a range of phenotypes informative about eukaryotic cell cycle control. These included mutants defining genes that were rate-limiting for the onset of mitosis and of the S-phase, that were responsible for there being only one S-phase in each cell cycle, and that ensured that mitosis only took place when S-phase was properly completed. This is a brief account of the discovery of these mutants and how they led to the identification of cyclin-dependent kinases as core to these cell cycle controls.

scholarly journals A Meiosis-Specific Cyclin Regulated by Splicing Is Required for Proper Progression through Meiosis

2005 ◽  
Vol 25 (15) ◽  
pp. 6330-6337 ◽  
Author(s):  
Jordi Malapeira ◽  
Alberto Moldón ◽  
Elena Hidalgo ◽  
Gerald R. Smith ◽  
Paul Nurse ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Chromosome Segregation ◽  
Mitotic Cycle ◽  
Mitotic Cell ◽  
S Phase ◽  
Mitotic Cell Cycle ◽  
Meiotic Cell ◽  
Cyclin Dependent Kinases ◽  
Negative Factor

ABSTRACT The meiotic cell cycle is modified from the mitotic cell cycle by having a premeiotic S phase which leads to high levels of recombination, a reductional pattern of chromosome segregation at the first division, and a second division with no intervening DNA synthesis. Cyclin-dependent kinases are essential for progression through the meiotic cell cycle, as for the mitotic cycle. Here we show that a fission yeast cyclin, Rem1, is present only during meiosis. Cells lacking Rem1 have impaired meiotic recombination, and Rem1 is required for premeiotic DNA synthesis when Cig2 is not present. rem1 expression is regulated at the level of both transcription and splicing, with Mei4 as a positive and Cig2 a negative factor of rem1 splicing. This regulation ensures the timely appearance of the different cyclins during meiosis, which is required for the proper progression through the meiotic cell cycle. We propose that the meiosis-specific B-type cyclin Rem1 has a central role in bringing about progression through meiosis.

Role of the Sulfolobus shibatae viral T6 initiator in conferring promoter strength and in influencing transcription start site selection

2006 ◽  
Vol 52 (11) ◽  
pp. 1136-1140 ◽  
Author(s):  
Sohail A Qureshi
Keyword(s):  
Transcription Start Site ◽  
Dna Sequences ◽  
Site Selection ◽  
Core Promoter ◽  
Promoter Strength ◽  
Start Site ◽  
Transcription Start ◽  
Recognition Element ◽  
Sulfolobus Shibatae

Archaeal promoters contain a TATA-box, an adjacent upstream TFB-recognition element (BRE), and a downstream initiator (INR) region from which transcription originates. While the contribution of A-box and BRE to promoter strength is well established, the role of DNA sequences within the INR region and its vicinity on transcription efficiency and start site selection remains unclear. Here, I demonstrate using the strong Sulfolobus shibatae viral T6 promoter that either substitution of its natural sequence from –17 and beyond with plasmid DNA or introduction of point transversion mutations at +3, –2, –4, and –5 positions reduce promoter strength dramatically, whereas +1, –1, and –2 mutations influence the transcription start site. These data therefore reveal that the INR region plays a role as important as the BRE and the A-box in T6 gene transcription. Key words: Archaea, transcription, initiator (INR), Sulfolobus shibatae, core promoter.

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