Eleven novelsep genes ofSchizosaccharomyces pombe required for efficient cell separation and sexual differentiation

Grallert, Ágnes; Grallert, Beáta; Zilahi, Erika; Szilágyi, Zsolt; Sipiczki, Matthias

doi:10.1002/(sici)1097-0061(19990615)15:8<669::aid-yea411>3.0.co;2-k

Cited by 33 publications

(33 citation statements)

References 48 publications

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“…Each compartment underwent anaphase with similar timing, suggesting that the decision to commit to mitosis was occurring with similar timing in each compartment. This is in contrast to mitotic controls in sep mutants, in which the two compartments either side of the septum undergo mitosis asynchronously (Grallert et al, 1999). This distinction suggests that the septation following osmotic shock is incomplete and that the two compartments share a common cytoplasm.…”

Section: Discussionmentioning

confidence: 64%

Stress-regulated kinase pathways in the recovery of tip growth and microtubule dynamics following osmotic stress inS. pombe

Robertson

Hagan

2008

Journal of Cell Science

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The cell-integrity and stress-response MAP kinase pathways (CIP and SRP, respectively) are stimulated by various environmental stresses. Ssp1 kinase modulates actin dynamics and is rapidly recruited to the plasma membrane following osmotic stress. Here, we show that osmotic stress arrested tip growth, induced the deposition of abnormal cell-wall deposits at tips and led to disassociation of F-actin foci from cell tips together with a reduction in the amount of F-actin in these foci. Osmotic stress also `froze' the dynamics of interphase microtubule bundles, with microtubules remaining static for approximately 38 minutes (at 30°C) before fragmenting upon return to dynamic behaviour. The timing with which microtubules resumed dynamic behaviour relied upon SRP activation of Atf1-mediated transcription, but not on either CIP or Ssp1 signalling. Analysis of the recovery of tip growth showed that: (1) the timing of recovery was controlled by SRP-stimulated Atf1 transcription; (2) re-establishment of polarized tip growth was absolutely dependent upon SRP and partially dependent upon Ssp1 signalling; and (3) selection of the site for polarized tip extension required Ssp1 and the SRP-associated polarity factor Wsh3 (also known as Tea4). CIP signalling did not impact upon any aspect of recovery. The normal kinetics of tip growth following osmotic stress of plo1.S402A/E mutants established that SRP control over the resumption of tip growth after osmotic stress is distinct from its control of tip growth following heat or gravitational stresses.

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Section: Discussionmentioning

confidence: 64%

Stress-regulated kinase pathways in the recovery of tip growth and microtubule dynamics following osmotic stress inS. pombe

Robertson

Hagan

2008

Journal of Cell Science

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“…These subunits belong to the Mediator middle module known to contact Pol II (23), and they are essential in yeast. Med31 interacts with subunits of the middle module (24,25), but is essential neither in S. cerevisiae nor in Schizosaccharomyces pombe (26) despite its strong conservation. This situation could be explained if the role of Med31 and TFIIS in conjunction during transcription initiation also holds in eukaryote species other than S. cerevisiae, a very likely possibility in view of the strong conservation of TFIIS throughout the eukaryotic kingdom.…”

Section: Discussionmentioning

confidence: 99%

TFIIS elongation factor and Mediator act in conjunction during transcription initiation in vivo

Guglielmi

Soutourina

Esnault

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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The transcription initiation and elongation steps of protein-coding genes usually rely on unrelated protein complexes. However, the TFIIS elongation factor is implicated in both processes. We found that, in the absence of the Med31 Mediator subunit, yeast cells required the TFIIS polymerase II (Pol II)-binding domain but not its RNA cleavage stimulatory activity that is associated with its elongation function. We also found that the TFIIS Pol II-interacting domain was needed for the full recruitment of Pol II to several promoters in the absence of Med31. This work demonstrated that, in addition to its thoroughly characterized role in transcription elongation, TFIIS is implicated through its Pol II-binding domain in the formation or stabilization of the transcription initiation complex in vivo.RNA polymerase II ͉ Saccharomyces cerevisiae ͉ transcription regulation ͉ Med31 ͉ Mediator subunit T he transcription of protein-coding eukaryotic genes by RNA polymerase II (Pol II) requires three successive steps: initiation, elongation, and termination. Transcription initiation of class II genes involves the binding of activators to regulatory sequences; the recruitment of RNA Pol II to the core promoter via interactions with activators, coactivators, and general transcription factors; and the initiation reaction per se with DNA strand opening and abortive initiation (1). A major coactivator target of transcriptional activators is the Mediator (2, 3). One of its activities is the recruitment and/or stabilization of Pol II at core promoters (4). After transcription initiation, Pol II enters elongation, during which it can be arrested because of the presence of specific DNA sequences that promote pausing, or because of obstacles such as DNA damage or bound proteins. To avoid or escape arrest, Pol II requires different elongation factors, including TFIIS (5). Evidence suggests that TFIIS could be implicated in both initiation and elongation.In vitro, TFIIS can reactivate arrested elongation complexes by stimulating endonucleolytic cleavage by Pol II of the nascent RNA (5). TFIIS is composed of three domains that fold independently, as demonstrated by NMR analysis of its structure (6, 7). Cleavage-stimulating activity minimally requires the Cterminal two-thirds of the protein, that is, its domain II and III separated by a 15-aa linker (7,8). Domain II forms a three-helix bundle followed by three short helices, with a basic patch on the third helix (␣-3) that is essential for TFIIS binding to Pol II (7). Crystallographic analysis of a TFIIS-Pol II complex confirmed that this basic patch lies at the TFIIS-Pol II interface (7,8). TFIIS binding to Pol II is required for domain III to reach the Pol II active site. Domain III forms a zinc ribbon that contains a conserved RSADE motif, responsible for the stimulation of RNA cleavage (7,8).TFIIS is also implicated in transcription initiation. First, the deletion of the DST1 gene, encoding TFIIS in yeast, is colethal with the deletion of the gene encoding the Med31 subunit of the Medi...

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“…The response of cells to hyperosmotic conditions, the presence of high concentrations of salts, and hyperoxidative and heat stress conditions was tested as described previously (9).…”

Section: Methodsmentioning

confidence: 99%

Role of Cell Shape in Determination of the Division Plane in Schizosaccharomyces pombe : Random Orientation of Septa in Spherical Cells

Sipiczki

Yamaguchi

Grallert³

et al. 2000

J Bacteriol

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The establishment of growth polarity in Schizosaccharomyces pombe cells is a combined function of the cytoplasmic cytoskeleton and the shape of the cell wall inherited from the mother cell. The septum that divides the cylindrical cell into two siblings is formed midway between the growing poles and perpendicularly to the axis that connects them. Since the daughter cells also extend at their ends and form their septa at right angles to the longitudinal axis, their septal (division) planes lie parallel to those of the mother cell. To gain a better understanding of how this regularity is ensured, we investigated septation in spherical cells that do not inherit morphologically predetermined cell ends to establish poles for growth. We studied four mutants (defining four novel genes), over 95% of whose cells displayed a completely spherical morphology and a deficiency in mating and showed a random distribution of cytoplasmic microtubules, Tea1p, and F-actin, indicating that the cytoplasmic cytoskeleton was poorly polarized or apolar. Septum positioning was examined by visualizing septa and division scars by calcofluor staining and by the analysis of electron microscopic images. Freeze-substitution, freeze-etching, and scanning electron microscopy were used. We found that the elongated bipolar shape is not essential for the determination of a division plane that can separate the postmitotic nuclei. However, it seems to be necessary for the maintenance of the parallel orientation of septa over the generations. In the spherical cells, the division scars and septa usually lie at angles to each other on the cell surface. We hypothesize that the shape of the cell indirectly affects the positioning of the septum by directing the extension of the spindle.Cell polarization is a fundamental requirement of cell growth, division, and differentiation. The polar growth ensures directed cell extension, the correct organization of cytoskeletal structures, and the development of proper cell shape (for recent reviews, see references 8, 16, 23, 25, and 35) and orients the mitotic spindle (reviewed in references 22, 36, and 48). In most animal and plant species, the mitotic spindle then determines the plane of division (39,52). In the budding yeast Saccharomyces cerevisiae, the division plane is independent of spindle orientation because it is predetermined by the position of the bud (18). The division takes place at the narrow neck between the mother and bud cells. The site of bud formation is determined by the location of a previous one, and the axis of the spindle is oriented by directing cytoplasmic microtubules running from the spindle pole body into the bud (17, 18).

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Eleven novelsep genes ofSchizosaccharomyces pombe required for efficient cell separation and sexual differentiation

Cited by 33 publications

References 48 publications

Stress-regulated kinase pathways in the recovery of tip growth and microtubule dynamics following osmotic stress inS. pombe

Stress-regulated kinase pathways in the recovery of tip growth and microtubule dynamics following osmotic stress inS. pombe

TFIIS elongation factor and Mediator act in conjunction during transcription initiation in vivo

Role of Cell Shape in Determination of the Division Plane in Schizosaccharomyces pombe : Random Orientation of Septa in Spherical Cells

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