scholarly journals Temporal regulation of morphogenetic events inSaccharomyces cerevisiae

2018 ◽  
Vol 29 (17) ◽  
pp. 2069-2083 ◽  
Author(s):  
Helen Lai ◽  
Jian-Geng Chiou ◽  
Anastasia Zhurikhina ◽  
Trevin R. Zyla ◽  
Denis Tsygankov ◽  
...  
Keyword(s):  
Cell Wall ◽  
Budding Yeast ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Temporal Regulation ◽  
Bud Emergence ◽  
Polarized Secretion ◽  
Local Cell ◽  
Actin Cables ◽  
Bud Site

Tip growth in fungi involves highly polarized secretion and modification of the cell wall at the growing tip. The genetic requirements for initiating polarized growth are perhaps best understood for the model budding yeast Saccharomyces cerevisiae. Once the cell is committed to enter the cell cycle by activation of G1 cyclin/cyclin-dependent kinase (CDK) complexes, the polarity regulator Cdc42 becomes concentrated at the presumptive bud site, actin cables are oriented toward that site, and septin filaments assemble into a ring around the polarity site. Several minutes later, the bud emerges. Here, we investigated the mechanisms that regulate the timing of these events at the single-cell level. Septin recruitment was delayed relative to polarity establishment, and our findings suggest that a CDK-dependent septin “priming” facilitates septin recruitment by Cdc42. Bud emergence was delayed relative to the initiation of polarized secretion, and our findings suggest that the delay reflects the time needed to weaken the cell wall sufficiently for the cell to bud. Rho1 activation by Rom2 occurred at around the time of bud emergence, perhaps in response to local cell-wall weakening. This report reveals regulatory mechanisms underlying the morphogenetic events in the budding yeast.

Cdc28-Clb mitotic kinase negatively regulates bud site assembly in the budding yeast

2001 ◽  
Vol 114 (1) ◽  
pp. 207-218 ◽  
Author(s):  
C.G. Padmashree ◽  
U. Surana
Keyword(s):  
Kinase Activity ◽  
Budding Yeast ◽  
Critical Role ◽  
The Other ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Formation ◽  
Temporal Regulation ◽  
Mitotic Kinase ◽  
Cortical Localization ◽  
Bud Site

In the budding yeast Saccharomyces cerevisiae, a prospective mother normally commences the formation of a daughter (the bud) only in the G(1) phase of the cell division cycle. This suggests a strict temporal regulation of the processes that initiate the formation of a new bud. Using cortical localization of bud site components Spa2 and Bni1 as an indicator of bud site assembly, we show that cells assemble a bud site following inactivation of the Cdc28-Clb mitotic kinase but prior to START. Interestingly, an untimely inactivation of the mitotic kinase is sufficient to drive cells to assemble a new bud site inappropriately in G(2) or M phases. The induction of Cdc28/Clb kinase activity in G(1), on the other hand, dramatically reduces a cell's ability to construct an incipient bud site. Our findings strongly suggest that the Cdc28-Clb kinase plays a critical role in the mechanism that restricts the timing of bud formation to the G(1) phase of the cell cycle.

Yeast RHO3 and RHO4 ras superfamily genes are necessary for bud growth, and their defect is suppressed by a high dose of bud formation genes CDC42 and BEM1

1992 ◽  
Vol 12 (12) ◽  
pp. 5690-5699 ◽  
Author(s):  
Y Matsui ◽  
A Toh-E
Keyword(s):  
Cell Polarity ◽  
Inhibitory Effect ◽  
High Dose ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Formation ◽  
Stabilizing Agents ◽  
Daughter Cells ◽  
Bud Emergence ◽  
Ras Superfamily ◽  
Bud Site

RHO3 and RHO4 are members of the ras superfamily genes of the yeast Saccharomyces cerevisiae and are related functionally to each other. Experiments using a conditionally expressed allele of RHO4 revealed that depletion of both the RHO3 and RHO4 gene products resulted in lysis of cells with a small bud, which could be prevented by the presence of osmotic stabilizing agents in the medium. rho3 rho4 cells incubated in medium containing an osmotic stabilizing agent were rounded and enlarged and displayed delocalized deposition of chitin and delocalization of actin patches, indicating that these cells lost cell polarity. Nine genes whose overexpression could suppress the defect of the RHO3 function were isolated (SRO genes). Two of them were identical with CDC42 and BEM1, bud site assembly genes involved in the process of bud emergence. A high dose of CDC42 complemented the rho3 defect, whereas overexpression of RHO3 had an inhibitory effect on the growth of mutants defective in the CDC24-CDC42 pathway. These results, along with comparison of cell morphology between rho3 rho4 cells and cdc24 (or cdc42) mutant cells kept under the restrictive conditions, strongly suggest that the functions of RHO3 and RHO4 are required after initiation of bud formation to maintain cell polarity during maturation of daughter cells.

Nuclear behaviour and cell wall composition in relation to budding in mutants of the yeast Saccharomyces cerevisiae

1986 ◽  
Vol 64 (1) ◽  
pp. 193-200 ◽  
Author(s):  
Mario Lachapelle ◽  
E. Roger Boothroyd
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Spindle Pole ◽  
Minor Role ◽  
Temperature Sensitive ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Emergence ◽  
Spindle Elongation ◽  
10 Nm Filaments ◽  
A Minor

A temperature-sensitive, cell division cycle mutant (cdc24–1) and karyogamy-deficient (kar1) mutant of Saccharomyces cerevisiae, both of which can produce binucleate or multinucleate cells, were used to study certain aspects of budding, after fluorescent staining for mannan, chitin, and nuclei (DNA). In most binucleate cells the two nuclei lay close together and divided into the same bud. In a few, however, the nuclei were far apart and one or two buds were formed, each proximal to a nucleus. The proximity of daughter nuclei in most blocked cdc24–1 cells suggests a role for the CDC24 gene product in spindle elongation. The relationship between the nuclei and the number and location of buds supports the theory of a preponderant role for the nucleus in budding. Although buds develop preferentially in regions of low chitin content in kar1 heterokaryons, the ability of cdc24–1 cells to bud even with a uniformly high content of chitin and mannan suggests a minor role for these cell wall constituents in determining the sites of bud emergence. The chitin ring is not needed for bud emergence but seems to play a role in normal bud development and in septum formation. Electron microscopy of cdc24–1 cells blocked (37 °C) for 8 h and released (23 °C) for 30 min showed morphologically normal spindle pole bodies, cytoplasmic microtubules, and intranuclear spindles. Although the chitin ring was absent, the ring of 10-nm filaments was present, consistent with its proposed role in bud emergence.

scholarly journals Sneaking Out for Happy Hour: Yeast-Based Approaches to Explore and Modulate Immune Response and Immune Evasion

Genes ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 667 ◽  
Author(s):  
Gaëlle Angrand ◽  
Alicia Quillévéré ◽  
Nadège Loaëc ◽  
Chrysoula Daskalogianni ◽  
Anton Granzhan ◽  
...  
Keyword(s):  
Cell Wall ◽  
Immune System ◽  
Immune Evasion ◽  
Budding Yeast ◽  
Pathogenic Fungi ◽  
Surface Proteins ◽  
Host Immune System ◽  
Antigenic Peptides ◽  
Yeast Saccharomyces Cerevisiae ◽  
Barr Virus

Many pathogens (virus, bacteria, fungi, or parasites) have developed a wide variety of mechanisms to evade their host immune system. The budding yeast Saccharomyces cerevisiae has successfully been used to decipher some of these immune evasion strategies. This includes the cis-acting mechanism that limits the expression of the oncogenic Epstein–Barr virus (EBV)-encoded EBNA1 and thus of antigenic peptides derived from this essential but highly antigenic viral protein. Studies based on budding yeast have also revealed the molecular bases of epigenetic switching or recombination underlying the silencing of all except one members of extended families of genes that encode closely related and highly antigenic surface proteins. This mechanism is exploited by several parasites (that include pathogens such as Plasmodium, Trypanosoma, Candida, or Pneumocystis) to alternate their surface antigens, thereby evading the immune system. Yeast can itself be a pathogen, and pathogenic fungi such as Candida albicans, which is phylogenetically very close to S. cerevisiae, have developed stealthiness strategies that include changes in their cell wall composition, or epitope-masking, to control production or exposure of highly antigenic but essential polysaccharides in their cell wall. Finally, due to the high antigenicity of its cell wall, yeast has been opportunistically exploited to create adjuvants and vectors for vaccination.

scholarly journals Temporal regulation of cell polarity via the interaction of the Ras GTPase Rsr1 and the scaffold protein Bem1

2019 ◽  
Vol 30 (20) ◽  
pp. 2543-2557 ◽  
Author(s):  
Kristi E. Miller ◽  
Wing-Cheong Lo ◽  
Ching-Shan Chou ◽  
Hay-Oak Park
Keyword(s):  
Bound States ◽  
Scaffold Protein ◽  
Cell Polarization ◽  
Temporal Regulation ◽  
Ras Gtpase ◽  
Polarized Secretion ◽  
Associated Proteins ◽  
Guanosine Triphosphatase ◽  
Bud Site

The Cdc42 guanosine triphosphatase (GTPase) plays a central role in polarity development in species ranging from yeast to humans. In budding yeast, a specific growth site is selected in the G1 phase. Rsr1, a Ras GTPase, interacts with Cdc42 and its associated proteins to promote polarized growth at the proper bud site. Yet how Rsr1 regulates cell polarization is not fully understood. Here, we show that Rsr1-GDP interacts with the scaffold protein Bem1 in early G1, likely hindering the role of Bem1 in Cdc42 polarization and polarized secretion. Consistent with these in vivo observations, mathematical modeling predicts that Bem1 is unable to promote Cdc42 polarization in early G1 in the presence of Rsr1-GDP. We find that a part of the Bem1 Phox homology domain, which overlaps with a region interacting with the exocyst component Exo70, is necessary for the association of Bem1 with Rsr1-GDP. Overexpression of the GDP-locked Rsr1 interferes with Bem1-dependent Exo70 polarization. We thus propose that Rsr1 functions in spatial and temporal regulation of polarity establishment by associating with distinct polarity factors in its GTP- and GDP-bound states.

scholarly journals Saccharomyces spores are born prepolarized to outgrow away from spore-spore connections and penetrate the ascus wall

2020 ◽  
Author(s):  
Lydia R. Heasley ◽  
Emily Singer ◽  
Michael A. McMurray
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Wall ◽  
Life Cycle ◽  
Fission Yeast ◽  
Site Selection ◽  
De Novo ◽  
Diploid Cell ◽  
Break Symmetry ◽  
Local Cell ◽  
Bud Site

1.AbstractHow non-spore haploid Saccharomyces cells choose sites of budding and polarize towards pheromone signals in order to mate has been a subject of intense study. Unlike non-spore haploids, sibling spores produced via meiosis and sporulation by a diploid cell are physically interconnected and encased in a sac derived from the old cell wall of the diploid, called the ascus. Non-spore haploids bud adjacent to previous sites of budding, relying on stable cortical landmarks laid down during prior divisions, but since spore membranes are made de novo it was assumed that, as is known for fission yeast, Saccharomyces spores break symmetry and polarize at random locations. Here we show that this assumption is incorrect: Saccharomyces cerevisiae spores are born prepolarized to outgrow, prior to budding or mating, away from interspore bridges. Consequently, when spores bud within an intact ascus, their buds locally penetrate the ascus wall, and when they mate, the resulting zygotes adopt a unique morphology reflective of re-polarization towards pheromone, which we dub the derrière. Long-lived cortical foci containing the septin Cdc10 mark polarity sites, but the canonical bud site selection program is dispensable for spore polarity, thus the origin and molecular composition of these landmarks remain unknown. These findings demand further investigation of previously overlooked mechanisms of polarity establishment and local cell wall digestion, and highlight how a key step in the Saccharomyces life cycle has been historically neglected.

scholarly journals Yeast RHO3 and RHO4 ras superfamily genes are necessary for bud growth, and their defect is suppressed by a high dose of bud formation genes CDC42 and BEM1.

1992 ◽  
Vol 12 (12) ◽  
pp. 5690-5699 ◽  
Author(s):  
Y Matsui ◽  
A Toh-E
Keyword(s):  
Cell Polarity ◽  
Inhibitory Effect ◽  
High Dose ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Formation ◽  
Stabilizing Agents ◽  
Daughter Cells ◽  
Bud Emergence ◽  
Ras Superfamily ◽  
Bud Site

RHO3 and RHO4 are members of the ras superfamily genes of the yeast Saccharomyces cerevisiae and are related functionally to each other. Experiments using a conditionally expressed allele of RHO4 revealed that depletion of both the RHO3 and RHO4 gene products resulted in lysis of cells with a small bud, which could be prevented by the presence of osmotic stabilizing agents in the medium. rho3 rho4 cells incubated in medium containing an osmotic stabilizing agent were rounded and enlarged and displayed delocalized deposition of chitin and delocalization of actin patches, indicating that these cells lost cell polarity. Nine genes whose overexpression could suppress the defect of the RHO3 function were isolated (SRO genes). Two of them were identical with CDC42 and BEM1, bud site assembly genes involved in the process of bud emergence. A high dose of CDC42 complemented the rho3 defect, whereas overexpression of RHO3 had an inhibitory effect on the growth of mutants defective in the CDC24-CDC42 pathway. These results, along with comparison of cell morphology between rho3 rho4 cells and cdc24 (or cdc42) mutant cells kept under the restrictive conditions, strongly suggest that the functions of RHO3 and RHO4 are required after initiation of bud formation to maintain cell polarity during maturation of daughter cells.

scholarly journals Kinetic Analysis of a Molecular Model of the Budding Yeast Cell Cycle

2000 ◽  
Vol 11 (1) ◽  
pp. 369-391 ◽  
Author(s):  
Katherine C. Chen ◽  
Attila Csikasz-Nagy ◽  
Bela Gyorffy ◽  
John Val ◽  
Bela Novak ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Molecular Model ◽  
Cell Cycle Control ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bud Emergence ◽  
Molecular Events ◽  
Eukaryotic Organism ◽  
Molecular Machinery ◽  
Time Courses

The molecular machinery of cell cycle control is known in more detail for budding yeast, Saccharomyces cerevisiae, than for any other eukaryotic organism. In recent years, many elegant experiments on budding yeast have dissected the roles of cyclin molecules (Cln1–3 and Clb1–6) in coordinating the events of DNA synthesis, bud emergence, spindle formation, nuclear division, and cell separation. These experimental clues suggest a mechanism for the principal molecular interactions controlling cyclin synthesis and degradation. Using standard techniques of biochemical kinetics, we convert the mechanism into a set of differential equations, which describe the time courses of three major classes of cyclin-dependent kinase activities. Model in hand, we examine the molecular events controlling “Start” (the commitment step to a new round of chromosome replication, bud formation, and mitosis) and “Finish” (the transition from metaphase to anaphase, when sister chromatids are pulled apart and the bud separates from the mother cell) in wild-type cells and 50 mutants. The model accounts for many details of the physiology, biochemistry, and genetics of cell cycle control in budding yeast.

scholarly journals Tropomyosin-containing Actin Cables Direct the Myo2p-dependent Polarized Delivery of Secretory Vesicles in Budding Yeast

1998 ◽  
Vol 143 (7) ◽  
pp. 1931-1945 ◽  
Author(s):  
David W. Pruyne ◽  
Daniel H. Schott ◽  
Anthony Bretscher
Keyword(s):  
Budding Yeast ◽  
Secretory Vesicle ◽  
Rab Gtpase ◽  
Secretory Vesicles ◽  
Class V ◽  
Bud Emergence ◽  
Isotropic Distribution ◽  
Bud Growth ◽  
Polarized Delivery ◽  
Actin Cables

The actin cytoskeleton in budding yeast consists of cortical patches and cables, both of which polarize toward regions of cell growth. Tropomyosin localizes specifically to actin cables and not cortical patches. Upon shifting cells with conditionally defective tropomyosin to restrictive temperatures, actin cables disappear within 1 min and both the unconventional class V myosin Myo2p and the secretory vesicle–associated Rab GTPase Sec4p depolarize rapidly. Bud growth ceases and the mother cell grows isotropically. When returned to permissive temperatures, tropomyosin-containing cables reform within 1 min in polarized arrays. Cable reassembly permits rapid enrichment of Myo2p at the focus of nascent cables as well as the Myo2p-dependent recruitment of Sec4p and the exocyst protein Sec8p, and the initiation of bud emergence. With the loss of actin cables, cortical patches slowly assume an isotropic distribution within the cell and will repolarize only after restoration of cables. Therefore, actin cables respond to polarity cues independently of the overall distribution of cortical patches and are able to directly target the Myo2p-dependent delivery of secretory vesicles and polarization of growth.

scholarly journals Swf1p, a Member of the DHHC-CRD Family of Palmitoyltransferases, Regulates the Actin Cytoskeleton and Polarized Secretion Independently of Its DHHC Motif

2008 ◽  
Vol 19 (10) ◽  
pp. 4454-4468 ◽  
Author(s):  
Shubha A. Dighe ◽  
Keith G. Kozminski
Keyword(s):  
Actin Cytoskeleton ◽  
Rho Gtpase ◽  
Wild Type ◽  
Cortical Actin ◽  
Actin Organization ◽  
Bud Emergence ◽  
Polarized Secretion ◽  
Polarized Cell Growth ◽  
Actin Cables

Rho and Rab family GTPases play a key role in cytoskeletal organization and vesicular trafficking, but the exact mechanisms by which these GTPases regulate polarized cell growth are incompletely understood. A previous screen for genes that interact with CDC42, which encodes a Rho GTPase, found SWF1/PSL10. Here, we show Swf1p, a member of the DHHC-CRD family of palmitoyltransferases, localizes to actin cables and cortical actin patches in Saccharomyces cerevisiae. Deletion of SWF1 results in misorganization of the actin cytoskeleton and decreased stability of actin filaments in vivo. Cdc42p localization depends upon Swf1p primarily after bud emergence. Importantly, we revealed that the actin regulating activity of Swf1p is independent of its DHHC motif. A swf1 mutant, in which alanine substituted for the cysteine required for the palmitoylation activity of DHHC-CRD proteins, displayed wild-type actin organization and Cdc42p localization. Bgl2p-marked exocytosis was found wild type in this mutant, although invertase secretion was impaired. These data indicate Swf1p has at least two distinct functions, one of which regulates actin organization and Bgl2p-marked secretion. This report is the first to link the function of a DHHC-CRD protein to Cdc42p and the regulation of the actin cytoskeleton.

Sign in / Sign up

Export Citation Format

Share Document