scholarly journals Patterns of bud-site selection in the yeast Saccharomyces cerevisiae.

1995 ◽  
Vol 129 (3) ◽  
pp. 751-765 ◽  
Author(s):  
J Chant ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Time Lapse ◽  
Growth Conditions ◽  
Alpha Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycles ◽  
Daughter Cells ◽  
Division Site ◽  
Mother Cells ◽  
Bud Site

Cells of the yeast Saccharomyces cerevisiae select bud sites in either of two distinct spatial patterns, known as axial (expressed by a and alpha cells) and bipolar (expressed by a/alpha cells). Fluorescence, time-lapse, and scanning electron microscopy have been used to obtain more precise descriptions of these patterns. From these descriptions, we conclude that in the axial pattern, the new bud forms directly adjacent to the division site in daughter cells and directly adjacent to the immediately preceding division site (bud site) in mother cells, with little influence from earlier sites. Thus, the division site appears to be marked by a spatial signal(s) that specifies the location of the new bud site and is transient in that it only lasts from one budding event to the next. Consistent with this conclusion, starvation and refeeding of axially budding cells results in the formation of new buds at nonaxial sites. In contrast, in bipolar budding cells, both poles are specified persistently as potential bud sites, as shown by the observations that a pole remains competent for budding even after several generations of nonuse and that the poles continue to be used for budding after starvation and refeeding. It appears that the specification of the two poles as potential bud sites occurs before a daughter cell forms its first bud, as a daughter can form this bud near either pole. However, there is a bias towards use of the pole distal to the division site. The strength of this bias varies from strain to strain, is affected by growth conditions, and diminishes in successive cell cycles. The first bud that forms near the distal pole appears to form at the very tip of the cell, whereas the first bud that forms near the pole proximal to the original division site (as marked by the birth scar) is generally somewhat offset from the tip and adjacent to (or overlapping) the birth scar. Subsequent buds can form near either pole and appear almost always to be adjacent either to the birth scar or to a previous bud site. These observations suggest that the distal tip of the cell and each division site carry persistent signals that can direct the selection of a bud site in any subsequent cell cycle.

scholarly journals Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (11) ◽  
pp. 2529-2531 ◽  
Author(s):  
B J Brewer ◽  
E Chlebowicz-Sledziewska ◽  
W L Fangman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cycle Phase ◽  
Cell Cycle Time ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycles ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Cell Cycle Phases ◽  
Mother Cells

During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

scholarly journals O-Glycosylation of Axl2/Bud10p by Pmt4p Is Required for Its Stability, Localization, and Function in Daughter Cells

1999 ◽  
Vol 145 (6) ◽  
pp. 1177-1188 ◽  
Author(s):  
Sylvia L. Sanders ◽  
Martina Gentzsch ◽  
Widmar Tanner ◽  
Ira Herskowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Site Selection ◽  
Surface Proteins ◽  
Cell Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Surface Proteins ◽  
Daughter Cells ◽  
Mother Cells ◽  
And Function ◽  
Bud Site

Cells of the yeast Saccharomyces cerevisiae choose bud sites in a manner that is dependent upon cell type: a and α cells select axial sites; a/α cells utilize bipolar sites. Mutants specifically defective in axial budding were isolated from an α strain using pseudohyphal growth as an assay. We found that a and α mutants defective in the previously identified PMT4 gene exhibit unipolar, rather than axial budding: mother cells choose axial bud sites, but daughter cells do not. PMT4 encodes a protein mannosyl transferase (pmt) required for O-linked glycosylation of some secretory and cell surface proteins (Immervoll, T., M. Gentzsch, and W. Tanner. 1995. Yeast. 11:1345–1351). We demonstrate that Axl2/Bud10p, which is required for the axial budding pattern, is an O-linked glycoprotein and is incompletely glycosylated, unstable, and mislocalized in cells lacking PMT4. Overexpression of AXL2 can partially restore proper bud-site selection to pmt4 mutants. These data indicate that Axl2/Bud10p is glycosylated by Pmt4p and that O-linked glycosylation increases Axl2/ Bud10p activity in daughter cells, apparently by enhancing its stability and promoting its localization to the plasma membrane.

scholarly journals Interactions among Rax1p, Rax2p, Bud8p, and Bud9p in Marking Cortical Sites for Bipolar Bud-site Selection in Yeast

2004 ◽  
Vol 15 (11) ◽  
pp. 5145-5157 ◽  
Author(s):  
Pil Jung Kang ◽  
Elizabeth Angerman ◽  
Kenichi Nakashima ◽  
John R. Pringle ◽  
Hay-Oak Park
Keyword(s):  
Cell Cortex ◽  
Type I ◽  
Yeast Saccharomyces Cerevisiae ◽  
Daughter Cells ◽  
Division Site ◽  
Distal Pole ◽  
Mother And Daughter ◽  
Mother Cells ◽  
Diploid Cells ◽  
Bud Site

In the budding yeast Saccharomyces cerevisiae, selection of the bud site determines the axis of polarized cell growth and eventual oriented cell division. Bud sites are selected in specific patterns depending on cell type. These patterns appear to depend on distinct types of marker proteins in the cell cortex; in particular, the bipolar budding of diploid cells depends on persistent landmarks at the birth-scar-distal and -proximal poles that involve the proteins Bud8p and Bud9p, respectively. Rax1p and Rax2p also appear to function specifically in bipolar budding, and we report here a further characterization of these proteins and of their interactions with Bud8p and Bud9p. Rax1p and Rax2p both appear to be integral membrane proteins. Although commonly used programs predict different topologies for Rax2p, glycosylation studies indicate that it has a type I orientation, with its long N-terminal domain in the extracytoplasmic space. Analysis of rax1 and rax2 mutant budding patterns indicates that both proteins are involved in selecting bud sites at both the distal and proximal poles of daughter cells as well as near previously used division sites on mother cells. Consistent with this, GFP-tagged Rax1p and Rax2p were both observed at the distal pole as well as at the division site on both mother and daughter cells; localization to the division sites was persistent through multiple cell cycles. Localization of Rax1p and Rax2p was interdependent, and biochemical studies showed that these proteins could be copurified from yeast. Bud8p and Bud9p could also be copurified with Rax1p, and localization studies provided further evidence of interactions. Localization of Rax1p and Rax2p to the bud tip and distal pole depended on Bud8p, and normal localization of Bud8p was partially dependent on Rax1p and Rax2p. Although localization of Rax1p and Rax2p to the division site did not appear to depend on Bud9p, normal localization of Bud9p appeared largely or entirely dependent on Rax1p and Rax2p. Taken together, the results indicate that Rax1p and Rax2p interact closely with each other and with Bud8p and Bud9p in the establishment and/or maintenance of the cortical landmarks for bipolar budding.

Cell cycle phases in the unequal mother/daughter cell cycles of Saccharomyces cerevisiae

1984 ◽  
Vol 4 (11) ◽  
pp. 2529-2531
Author(s):  
B J Brewer ◽  
E Chlebowicz-Sledziewska ◽  
W L Fangman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cycle Phase ◽  
Cell Cycle Time ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Cycles ◽  
Daughter Cells ◽  
Mother And Daughter ◽  
Cell Cycle Phases ◽  
Mother Cells

During cell division in the yeast Saccharomyces cerevisiae mother cells produce buds (daughter cells) which are smaller and have longer cell cycles. We performed experiments to compare the lengths of cell cycle phases in mothers and daughters. As anticipated from earlier indirect observations, the longer cell cycle time of daughter cells is accounted for by a longer G1 interval. The S-phase and the G2-phase are of the same duration in mother and daughter cells. An analysis of five isogenic strains shows that cell cycle phase lengths are independent of cell ploidy and mating type.

scholarly journals Daughter cells of Saccharomyces cerevisiae from old mothers display a reduced life span.

1994 ◽  
Vol 127 (6) ◽  
pp. 1985-1993 ◽  
Author(s):  
B K Kennedy ◽  
N R Austriaco ◽  
L Guarente
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Life Span ◽  
Daughter Cell ◽  
Young Mothers ◽  
Young Mother ◽  
Yeast Saccharomyces Cerevisiae ◽  
Daughter Cells ◽  
Per Se ◽  
Mother Cells ◽  
Maximum Occurrence

The yeast Saccharomyces cerevisiae typically divides asymmetrically to give a large mother cell and a smaller daughter cell. As mother cells become old, they enlarge and produce daughter cells that are larger than daughters derived from young mother cells. We found that occasional daughter cells were indistinguishable in size from their mothers, giving rise to a symmetric division. The frequency of symmetric divisions became greater as mother cells aged and reached a maximum occurrence of 30% in mothers undergoing their last cell division. Symmetric divisions occurred similarly in rad9 and ste12 mutants. Strikingly, daughters from old mothers, whether they arose from symmetric divisions or not, displayed reduced life spans relative to daughters from young mothers. Because daughters from old mothers were larger than daughters from young mothers, we investigated whether an increased size per se shortened life span and found that it did not. These findings are consistent with a model for aging that invokes a senescence substance which accumulates in old mother cells and is inherited by their daughters.

scholarly journals Genetic analysis of the bipolar pattern of bud site selection in the yeast Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (4) ◽  
pp. 1857-1870 ◽  
Author(s):  
J E Zahner ◽  
H A Harkins ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Interaction ◽  
Previous Analysis ◽  
Intracellular Localization ◽  
Proximal Pole ◽  
Yeast Saccharomyces Cerevisiae ◽  
Novel Gene ◽  
Division Site ◽  
Genes Encoding ◽  
Bud Site

Previous analysis of the bipolar budding pattern of Saccharomyces cerevisiae has suggested that it depends on persistent positional signals that mark the region of the division site and the tip of the distal pole on a newborn daughter cell, as well as each previous division site on a mother cell. In an attempt to identify genes encoding components of these signals or proteins involved in positioning or responding to them, we identified 11 mutants with defects in bipolar but not in axial budding. Five mutants displaying a bipolar budding-specific randomization of budding pattern had mutations in four previously known genes (BUD2, BUD5, SPA2, and BNI1) and one novel gene (BUD6), respectively. As Bud2p and Bud5p are known to be required for both the axial and bipolar budding patterns, the alleles identified here probably encode proteins that have lost their ability to interact with the bipolar positional signals but have retained their ability to interact with the distinct positional signal used in axial budding. The function of Spa2p is not known, but previous work has shown that its intracellular localization is similar to that postulated for the bipolar positional signals. BNI1 was originally identified on the basis of genetic interaction with CDC12, which encodes one of the neck-filament-associated septin proteins, suggesting that these proteins may be involved in positioning the bipolar signals. One mutant with a heterogeneous budding pattern defines a second novel gene (BUD7). Two mutants budding almost exclusively from the proximal pole carry mutations in a fourth novel gene (BUD9). A bud8 bud9 double mutant also buds almost exclusively from the proximal pole, suggesting that Bud9p is involved in positioning the proximal pole signal rather than being itself a component of this signal.

scholarly journals Kar9p-independent Microtubule Capture at Bud6p Cortical Sites Primes Spindle Polarity before Bud Emergence in Saccharomyces cerevisiae

2002 ◽  
Vol 13 (12) ◽  
pp. 4141-4155 ◽  
Author(s):  
Marisa Segal ◽  
Kerry Bloom ◽  
Steven I. Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Live Cells ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Yeast Saccharomyces Cerevisiae ◽  
Chromosomal Segregation ◽  
Division Site ◽  
Bud Emergence ◽  
Mother Cells ◽  
Microtubule Capture

Spindle orientation is critical for accurate chromosomal segregation in eukaryotic cells. In the yeast Saccharomyces cerevisiae, orientation of the mitotic spindle is achieved by a program of microtubule–cortex interactions coupled to spindle morphogenesis. We previously implicated Bud6p in directing microtubule capture throughout this program. Herein, we have analyzed cells coexpressing GFP:Bud6 and GFP:Tub1 fusions, providing a kinetic view of Bud6p–microtubule interactions in live cells. Surprisingly, even during the G1 phase, microtubule capture at the recent division site and the incipient bud is dictated by Bud6p. These contacts are eliminated in bud6Δ cells but are proficient inkar9Δ cells. Thus, Bud6p cues microtubule capture, as soon as a new cell polarity axis is established independent of Kar9p. Bud6p increases the duration of interactions and promotes distinct modes of cortical association within the bud and neck regions. In particular, microtubule shrinkage and growth at the cortex rarely occur away from Bud6p sites. These are the interactions selectively impaired at the bud cortex in bud6Δ cells. Finally, interactions away from Bud6p sites within the bud differ from those occurring at the mother cell cortex, pointing to the existence of an independent factor controlling cortical contacts in mother cells after bud emergence.

scholarly journals Fine-tuning the orientation of the polarity axis by Rga1, a Cdc42 GTPase-activating protein

2017 ◽  
Vol 28 (26) ◽  
pp. 3773-3788 ◽  
Author(s):  
Kristi E. Miller ◽  
Wing-Cheong Lo ◽  
Mid Eum Lee ◽  
Pil Jung Kang ◽  
Hay-Oak Park
Keyword(s):  
Cell Polarization ◽  
Fine Tuning ◽  
Gtpase Activating Protein ◽  
Animal Cells ◽  
Daughter Cells ◽  
Division Site ◽  
Lim Domains ◽  
Mother Cells ◽  
Bud Site ◽  
Selection Of

In yeast and animal cells, signaling pathways involving small guanosine triphosphatases (GTPases) regulate cell polarization. In budding yeast, selection of a bud site directs polarity establishment and subsequently determines the plane of cell division. Rga1, a Cdc42 GTPase-activating protein, prevents budding within the division site by inhibiting Cdc42 repolarization. A protein complex including Nba1 and Nis1 is involved in preventing rebudding at old division sites, yet how these proteins and Rga1 might function in negative polarity signaling has been elusive. Here we show that Rga1 transiently localizes to the immediately preceding and older division sites by interacting with Nba1 and Nis1. The LIM domains of Rga1 are necessary for its interaction with Nba1, and loss of this interaction results in premature delocalization of Rga1 from the immediately preceding division site and, consequently, abnormal bud-site selection in daughter cells. However, such defects are minor in mother cells of these mutants, likely because the G1 phase is shorter and a new bud site is established prior to delocalization of Rga1. Indeed, our biphasic mathematical model of Cdc42 polarization predicts that premature delocalization of Rga1 leads to more frequent Cdc42 repolarization within the division site when the first temporal step in G1 is assumed to last longer. Spatial distribution of a Cdc42 GAP in coordination with G1 progression may thus be critical for fine-tuning the orientation of the polarity axis in yeast.

scholarly journals A Role for the Actin Cytoskeleton of Saccharomyces cerevisiae in Bipolar Bud-Site Selection

1997 ◽  
Vol 136 (1) ◽  
pp. 111-123 ◽  
Author(s):  
Shirley Yang ◽  
Kathryn R. Ayscough ◽  
David G. Drubin
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Site Selection ◽  
Mitotic Checkpoint ◽  
Cell Cortex ◽  
Spatial Cues ◽  
Genes Encoding ◽  
Mother And Daughter ◽  
Mother Cells ◽  
Bud Site

Saccharomyces cerevisiae cells select bud sites according to one of two predetermined patterns. MATa and MATα cells bud in an axial pattern, and MATa/α cells bud in a bipolar pattern. These budding patterns are thought to depend on the placement of spatial cues at specific sites in the cell cortex. Because cytoskeletal elements play a role in organizing the cytoplasm and establishing distinct plasma membrane domains, they are well suited for positioning bud-site selection cues. Indeed, the septin-containing neck filaments are crucial for establishing the axial budding pattern characteristic of MATa and MATα cells. In this study, we determined the budding patterns of cells carrying mutations in the actin gene or in genes encoding actin-associated proteins: MATa/α cells were defective in the bipolar budding pattern, but MATa and MATα cells still exhibit a normal axial budding pattern. We also observed that MATa/α actin cytoskeleton mutant daughter cells correctly position their first bud at the distal pole of the cell, but mother cells position their buds randomly. The actin cytoskeleton therefore functions in generation of the bipolar budding pattern and is required specifically for proper selection of bud sites in mother MATa/α cells. These observations and the results of double mutant studies support the conclusion that different rules govern bud-site selection in mother and daughter MATa/α cells. A defective bipolar budding pattern did not preclude an sla2-6 mutant from undergoing pseudohyphal growth, highlighting the central role of daughter cell bud-site selection cues in the formation of pseudohyphae. Finally, by examining the budding patterns of mad2-1 mitotic checkpoint mutants treated with benomyl to depolymerize their microtubules, we confirmed and extended previous evidence indicating that microtubules do not function in axial or bipolar bud-site selection.

scholarly journals Changes in the Min Oscillation Pattern before and after Cell Birth

2010 ◽  
Vol 192 (16) ◽  
pp. 4134-4142 ◽  
Author(s):  
Jennifer R. Juarez ◽  
William Margolin
Keyword(s):  
Cell Division ◽  
Fluorescent Protein ◽  
Time Lapse ◽  
The Other ◽  
Cell Pole ◽  
Daughter Cells ◽  
Division Site ◽  
Before And After ◽  
Dividing Cells ◽  
Green Fluorescent

ABSTRACT The Min system regulates the positioning of the cell division site in many bacteria. In Escherichia coli, MinD migrates rapidly from one cell pole to the other. In conjunction with MinC, MinD helps to prevent unwanted FtsZ rings from assembling at the poles and to stabilize their positioning at midcell. Using time-lapse microscopy of growing and dividing cells expressing a gfp-minD fusion, we show that green fluorescent protein (GFP)-MinD often paused at midcell in addition to at the poles, and the frequency of midcell pausing increased as cells grew longer and cell division approached. At later stages of septum formation, GFP-MinD often paused specifically on only one side of the septum, followed by migration to the other side of the septum or to a cell pole. About the time of septum closure, this irregular pattern often switched to a transient double pole-to-pole oscillation in the daughter cells, which ultimately became a stable double oscillation. The splitting of a single MinD zone into two depends on the developing septum and is a potential mechanism to explain how MinD is distributed equitably to both daughter cells. Septal pausing of GFP-MinD did not require MinC, suggesting that MinC-FtsZ interactions do not drive MinD-septal interactions, and instead MinD recognizes a specific geometric, lipid, and/or protein target at the developing septum. Finally, we observed regular end-to-end oscillation over very short distances along the long axes of minicells, supporting the importance of geometry in MinD localization.

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