scholarly journals A highly divergent gamma-tubulin gene is essential for cell growth and proper microtubule organization in Saccharomyces cerevisiae.

1995 ◽  
Vol 131 (6) ◽  
pp. 1775-1788 ◽  
Author(s):  
S G Sobel ◽  
M Snyder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Yeast Cell ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Predicted Amino Acid Sequence ◽  
Nuclear Staining ◽  
Microtubule Organization ◽  
Cytoplasmic Microtubule ◽  
Gamma Tubulin

A Saccharomyces cerevisiae gamma-tubulin-related gene, TUB4, has been characterized. The predicted amino acid sequence of the Tub4 protein (Tub4p) is 29-38% identical to members of the gamma-tubulin family. Indirect immunofluorescence experiments using a strain containing an epitope-tagged Tub4p indicate that Tub4p resides at the spindle pole body throughout the yeast cell cycle. Deletion of the TUB4 gene indicates that Tub4p is essential for yeast cell growth. Tub4p-depleted cells arrest during nuclear division; most arrested cells contain a large bud, replicated DNA, and a single nucleus. Immunofluorescence and nuclear staining experiments indicate that cells depleted of Tub4p contain defects in the organization of both cytoplasmic and nuclear microtubule arrays; such cells exhibit nuclear migration failure, defects in spindle formation, and/or aberrantly long cytoplasmic microtubule arrays. These data indicate that the S. cerevisiae gamma-tubulin protein is an important SPB component that organizes both cytoplasmic and nuclear microtubule arrays.

scholarly journals gamma-Tubulin-like Tub4p of Saccharomyces cerevisiae is associated with the spindle pole body substructures that organize microtubules and is required for mitotic spindle formation.

1996 ◽  
Vol 134 (2) ◽  
pp. 429-441 ◽  
Author(s):  
A Spang ◽  
S Geissler ◽  
K Grein ◽  
E Schiebel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spindle Pole Body ◽  
Mitotic Checkpoint ◽  
Spindle Pole ◽  
Checkpoint Control ◽  
Microtubule Organizing Center ◽  
Microtubule Organization ◽  
Spindle Formation ◽  
Pole Body ◽  
Gamma Tubulin

Tub4p is a novel tubulin in Saccharomyces cerevisiae that most closely resembles gamma-tubulin. We report in this manuscript that the essential Tub4p is associated with the inner and outer plaques of the yeast microtubule organizing center, the spindle pole body (SPB). These SPB substructures are involved in the attachment of the nuclear and cytoplasmic microtubules, respectively (Byers, B., and L. Goetsch. 1975. J. Bacteriol. 124:511-523). Study of a temperature sensitive tub4-1 allele revealed that TUB4 has essential functions in microtubule organization. Remarkably, SPB duplication and separation are not impaired in tub4-1 cells incubated at the nonpermissive temperature. However, SPBs from such cells contain less or misdirected nuclear microtubules. Further analysis revealed that tub4-1 cells are able to assemble a short bipolar spindle, suggesting that the defect in microtubule organization occurs after spindle formation. A role of Tub4p in microtubule organization is further suggested by an increase in chromosome loss in tub4-1 cells. In addition, cell cycle arrest and survival of tub4-1 cells is dependent on the mitotic checkpoint control gene BUB2 (Hoyt, M.A., L. Totis, B.T. Roberts. 1991. Cell. 66:507-517), one of the cell's monitors of spindle integrity.

scholarly journals Mto2p, a Novel Fission Yeast Protein Required for Cytoplasmic Microtubule Organization and Anchoring of the Cytokinetic Actin Ring

2005 ◽  
Vol 16 (6) ◽  
pp. 3052-3063 ◽  
Author(s):  
Srinivas Venkatram ◽  
Jennifer L. Jennings ◽  
Andrew Link ◽  
Kathleen L. Gould
Keyword(s):  
Fission Yeast ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Dependent Manner ◽  
Microtubule Organization ◽  
Actin Ring ◽  
Medial Region ◽  
Cytoplasmic Microtubule ◽  
Associated Proteins ◽  
Cytoplasmic Microtubules

Microtubules regulate diverse cellular processes, including chromosome segregation, nuclear positioning, and cytokinesis. In many organisms, microtubule nucleation requires γ-tubulin and associated proteins present at specific microtubule organizing centers (MTOCs). In fission yeast, interphase cytoplasmic microtubules originate from poorly characterized interphase MTOCs and spindle pole body (SPB), and during late anaphase from the equatorial MTOC (EMTOC). It has been previously shown that Mto1p (Mbo1p/Mod20p) function is important for the organization/nucleation of all cytoplasmic microtubules. Here, we show that Mto2p, a novel protein, interacts with Mto1p and is important for establishing a normal interphase cytoplasmic microtubule array. In addition, mto2Δ cells fail to establish a stable EMTOC and localize γ-tubulin complex members to this medial structure. As predicted from these functions, Mto2p localizes to microtubules, the SPB, and the EMTOC in an Mto1p-dependent manner. mto2Δ cells fail to anchor the cytokinetic actin ring in the medial region of the cell and under conditions that mildly perturb actin structures, these rings unravel in mto2Δ cells. Our results suggest that the Mto2p and the EMTOC are critical for anchoring the cytokinetic actin ring to the medial region of the cell and for proper coordination of mitosis with cytokinesis.

scholarly journals Absence of microtubule sliding and an analysis of spindle formation and elongation in isolated mitotic spindles from the yeast Saccharomyces cerevisiae.

1982 ◽  
Vol 94 (2) ◽  
pp. 341-349 ◽  
Author(s):  
S M King ◽  
J S Hyams ◽  
A Luba
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Mitotic Spindles ◽  
Microtubule Organization ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spindle Formation ◽  
Detailed Model ◽  
Thin Sections ◽  
Gold Thioglucose

Mitotic spindles were isolated from a cell division cycle mutant of the budding yeast Saccharomyces cerevisiae by the lysis of sphateroplasts on an air:buffer interface and were negatively stained with 1% gold thioglucose. Isolated spindles were incubated under conditions which promoted the sliding disintegration of parallel preparations of Tetrahymena axonemes, namely the addition of ATP to 20 microM. In no experiment was a corresponding change in microtubule organization of the spindle observed even when spindles were first pretreated with either 1-10 microgram/ml trypsin or 0.2-2% Triton X-100. During these experiments a number of spindles were isolated from cells that had passed through the imposed temperature block, and from the images obtained a detailed model of spindle formation and elongation has been constructed. Two sets of microtubules, one from each spindle pole body (SPB), completely interdigitate to form a continuous bundle, and a series of discontinuous microtubules are then nucleated by each SPB. As the spindle elongates, the number of microtubules continuous between the two SPBs decreases until, at a length of 4 micrometer, only one remains. The spindle, composed of only one microtubule, continues to elongate until it reaches the maximal nuclear dimension of 8 micrometer. The data obtained from negatively stained preparations have been verified in thin sections of wild-type cells. We suggest that, as in the later stages of mitosis only one microtubule is involved in the separation of the spindle poles, the microtubular spindle in S. cerevisiae is not a force-generating system but rather acts as a regulatory mechanism controlling the rate of separation.

scholarly journals Orderly assembly underpinning built-in asymmetry in the yeast centrosome duplication cycle requires cyclin-dependent kinase

2020 ◽  
Author(s):  
Marco Geymonat ◽  
Qiuran Peng ◽  
Zhiang Guo ◽  
Zulin Yu ◽  
Jay R. Unruh ◽  
...  
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Cyclin Dependent Kinase ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Microtubule Organization ◽  
Nucleation Sites ◽  
Stem Cell Divisions ◽  
Gamma Tubulin ◽  
Duplication Cycle

ABSTRACTAsymmetric astral microtubule organization drives the polarized orientation of the S. cerevisiae mitotic spindle and primes the invariant inheritance of the old spindle pole body (SPB, the yeast centrosome) by the bud. This model has anticipated analogous centrosome asymmetries featuring in self-renewing stem cell divisions. We previously implicated Spc72, the cytoplasmic receptor for the gamma-tubulin nucleation complex, as the most upstream determinant linking SPB age, functional asymmetry and fate. Here we used structured illumination microscopy and biochemical analysis to explore the asymmetric landscape of nucleation sites inherently built into the spindle pathway and under the control of cyclin-dependent kinase (CDK). We show that CDK enforces Spc72 asymmetric docking by phosphorylating Nud1/centriolin. Furthermore, CDK-imposed order in the construction of the new SPB promotes the correct balance of nucleation sites between the nuclear and cytoplasmic faces of the SPB. Together these contributions by CDK inherently link correct SPB morphogenesis, age and fate.

scholarly journals Orderly assembly underpinning built-in asymmetry in the yeast centrosome duplication cycle requires cyclin-dependent kinase

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Marco Geymonat ◽  
Qiuran Peng ◽  
Zhiang Guo ◽  
Zulin Yu ◽  
Jay R Unruh ◽  
...  
Keyword(s):  
Spindle Pole Body ◽  
Spindle Pole ◽  
Cyclin Dependent Kinase ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Microtubule Organization ◽  
Nucleation Sites ◽  
Stem Cell Divisions ◽  
Gamma Tubulin ◽  
Duplication Cycle

Asymmetric astral microtubule organization drives the polarized orientation of the S. cerevisiae mitotic spindle and primes the invariant inheritance of the old spindle pole body (SPB, the yeast centrosome) by the bud. This model has anticipated analogous centrosome asymmetries featured in self-renewing stem cell divisions. We previously implicated Spc72, the cytoplasmic receptor for the gamma-tubulin nucleation complex, as the most upstream determinant linking SPB age, functional asymmetry and fate. Here we used structured illumination microscopy and biochemical analysis to explore the asymmetric landscape of nucleation sites inherently built into the spindle pathway and under the control of cyclin-dependent kinase (CDK). We show that CDK enforces Spc72 asymmetric docking by phosphorylating Nud1/centriolin. Furthermore, CDK-imposed order in the construction of the new SPB promotes the correct balance of nucleation sites between the nuclear and cytoplasmic faces of the SPB. Together these contributions by CDK inherently link correct SPB morphogenesis, age and fate.

Ady3p Links Spindle Pole Body Function to Spore Wall Synthesis in Saccharomyces cerevisiae

Genetics ◽  
2002 ◽  
Vol 160 (4) ◽  
pp. 1439-1450
Author(s):  
Mark E Nickas ◽  
Aaron M Neiman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
De Novo ◽  
Spindle Pole Body ◽  
Leading Edge ◽  
Spindle Pole ◽  
Spore Wall ◽  
Pole Body ◽  
Prospore Membrane ◽  
Sporulation Efficiency ◽  
Spore Walls

Abstract Spore formation in Saccharomyces cerevisiae requires the de novo synthesis of prospore membranes and spore walls. Ady3p has been identified as an interaction partner for Mpc70p/Spo21p, a meiosis-specific component of the outer plaque of the spindle pole body (SPB) that is required for prospore membrane formation, and for Don1p, which forms a ring-like structure at the leading edge of the prospore membrane during meiosis II. ADY3 expression has been shown to be induced in midsporulation. We report here that Ady3p interacts with additional components of the outer and central plaques of the SPB in the two-hybrid assay. Cells that lack ADY3 display a decrease in sporulation efficiency, and most ady3Δ/ady3Δ asci that do form contain fewer than four spores. The sporulation defect in ady3Δ/ady3Δ cells is due to a failure to synthesize spore wall polymers. Ady3p forms ring-like structures around meiosis II spindles that colocalize with those formed by Don1p, and Don1p rings are absent during meiosis II in ady3Δ/ady3Δ cells. In mpc70Δ/mpc70Δ cells, Ady3p remains associated with SPBs during meiosis II. Our results suggest that Ady3p mediates assembly of the Don1p-containing structure at the leading edge of the prospore membrane via interaction with components of the SPB and that this structure is involved in spore wall formation.

scholarly journals The rye Mutants Identify a Role for Ssn/Srb Proteins of the RNA Polymerase II Holoenzyme During Stationary Phase Entry in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Ya-Wen Chang ◽  
Susie C Howard ◽  
Yelena V Budovskaya ◽  
Jasper Rine ◽  
Paul K Herman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Rna Polymerase ◽  
Stationary Phase ◽  
Yeast Cell ◽  
Rna Polymerase Ii ◽  
Transcriptional Response ◽  
Nutrient Deprivation ◽  
Ras Signaling ◽  
Rna Polymerase Ii Holoenzyme

Abstract Saccharomyces cerevisiae cells enter into a distinct resting state, known as stationary phase, in response to specific types of nutrient deprivation. We have identified a collection of mutants that exhibited a defective transcriptional response to nutrient limitation and failed to enter into a normal stationary phase. These rye mutants were isolated on the basis of defects in the regulation of YGP1 expression. In wild-type cells, YGP1 levels increased during the growth arrest caused by nutrient deprivation or inactivation of the Ras signaling pathway. In contrast, the levels of YGP1 and related genes were significantly elevated in the rye mutants during log phase growth. The rye defects were not specific to this YGP1 response as these mutants also exhibited multiple defects in stationary phase properties, including an inability to survive periods of prolonged starvation. These data indicated that the RYE genes might encode important regulators of yeast cell growth. Interestingly, three of the RYE genes encoded the Ssn/Srb proteins, Srb9p, Srb10p, and Srb11p, which are associated with the RNA polymerase II holoenzyme. Thus, the RNA polymerase II holoenzyme may be a target of the signaling pathways responsible for coordinating yeast cell growth with nutrient availability.

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