Establishment of Cell Polarity in Yeast

Pringle, John R.; Bi, Erfei; A., Harkins, H.; Zahner, J E; Virgilio, Claudio De; Chant, John; Corrado, Kathleen; Fares, Hanna

doi:10.1101/sqb.1995.060.01.079

Cited by 167 publications

(174 citation statements)

References 107 publications

(129 reference statements)

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“…a n ϭ 500. b n ϭ 100. results in the formation of "linear actin rings" and of delocalized septa. Here, we analyzed the A. gossypii homolog of ScRsr1p/ Bud1p that is essential for cell type-specific selection of new bud sites but has no known function in vegetative growth (Pringle et al, 1995). In the Agrsr1⌬ mutant, lateral branching was still initiated but often abandoned after a short period of polarized growth resulting in bulges along the hyphae.…”

Section: Bud-genes In a Gossypii Versus Bud-genes In S Cerevisiaementioning

confidence: 99%

“…In S. cerevisiae, BUD-genes take part in the selection of a new bud site (Herskowitz et al, 1995;Pringle et al, 1995;Madden and Snyder, 1998). This process is cell type specific.…”

Section: Bud-genes In a Gossypii Versus Bud-genes In S Cerevisiaementioning

confidence: 99%

“…In other filamentous fungi, Cdc42p has been localized to the hyphal tips of growing hyphae, suggesting its continuous requirement during hyphal growth (Gorfer et al, 2001). In S. cerevisiae, the machinery regulating the process of budsite selection acts upstream of CDC42 and acts in a cell type-specific way to impose either the axial budding pattern in MATa or MAT␣ haploid cells or the bipolar budding pattern in diploid MATa/␣ cells (Pringle et al, 1995;Herskowitz et al, 1995;Casamayor and Snyder, 2002). We have previously studied the role of the Ashbya gossypii BUD3 homolog, which in S. cerevisiae plays a role in the axial budding pattern (Chant and Herskowitz, 1991).…”

Section: Introductionmentioning

confidence: 99%

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A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous FungusAshbya gossypii

Bauer

Knechtle

Wendland

et al. 2004

MBoC

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Characteristic features of morphogenesis in filamentous fungi are sustained polar growth at tips of hyphae and frequent initiation of novel growth sites (branches) along the extending hyphae. We have begun to study regulation of this process on the molecular level by using the model fungus Ashbya gossypii. We found that the A. gossypii Ras-like GTPase Rsr1p/Bud1p localizes to the tip region and that it is involved in apical polarization of the actin cytoskeleton, a determinant of growth direction. In the absence of RSR1/BUD1, hyphal growth was severely slowed down due to frequent phases of pausing of growth at the hyphal tip. During pausing events a hyphal tip marker, encoded by the polarisome component AgSPA2, disappeared from the tip as was shown by in vivo time-lapse fluorescence microscopy of green fluorescent protein-labeled AgSpa2p. Reoccurrence of AgSpa2p was required for the resumption of hyphal growth. In the Agrsr1/bud1⌬ deletion mutant, resumption of growth occurred at the hyphal tip in a frequently uncoordinated manner to the previous axis of polarity. Additionally, hyphal filaments in the mutant developed aberrant branching sites by mislocalizing AgSpa2p thus distorting hyphal morphology. These results define AgRsr1p/Bud1p as a key regulator of hyphal growth guidance. INTRODUCTIONPolarized cell growth in both unicellular and multicellular organisms is a prerequisite for cellular and organ morphogenesis (Harold, 1995). Hyphal tip extensions of filamentous fungi, neuronal outgrowth in vertebrates, and extension of pollen tubes in plants are extreme examples of polarized cell growth. In the case of filamentous fungi, this leads to the production of long tubular cells, the hyphae. In general, polarized fungal growth occurs via the restriction of the delivery of new membrane and cell wall components to hyphal tips (Wendland, 2001;Momany, 2002). The actin cytoskeleton and microtubules play an important role in this targeted delivery of vesicles to sites of growth (Heath and Steinberg, 1999). The tendency of hyphae to grow in a stable direction for considerable distances is a property common to all filamentous fungi. This phenomenon requires growth guidance and the maintenance of growth direction similarly as found in neuronal cells (Luo, 2000;Dickson, 2001). As hyphae elongate at the tips, the growing tip is the prime place where growth guidance should be executed.Although much research has been done to understand the ability of hyphae to change their growth direction in response to external stimuli such as electrical fields, calcium concentration, and nutrient gradients, the internal determinants of growth guidance largely remain unknown (Gow, 1994). An interesting class of mutants of the ascomycete Neurospora crassa, the ropy mutants, revealed distorted hyphal morphologies and frequent loss of growth directionality that were correlated with sustained misalignments of the Spitzenkorper (vesicle supply center) at the hyphal tip (Riquelme et al., 2000). N. crassa ropy mutants were found to encode component...

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Section: Bud-genes In a Gossypii Versus Bud-genes In S Cerevisiaementioning

confidence: 99%

“…In S. cerevisiae, BUD-genes take part in the selection of a new bud site (Herskowitz et al, 1995;Pringle et al, 1995;Madden and Snyder, 1998). This process is cell type specific.…”

Section: Bud-genes In a Gossypii Versus Bud-genes In S Cerevisiaementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous FungusAshbya gossypii

Bauer

Knechtle

Wendland

et al. 2004

MBoC

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“…In S. cerevisiae, the actin cytoskeleton is responsible for delivering secretory vesicles to specific areas of the cell surface; as actin organization changes during the cell cycle, the patterns of vesicle delivery show corresponding changes (Lew and Reed, 1995;Pringle et al, 1995;Pruyne and Bretscher, 2000b). Because plasma membrane and cell wall proteins travel to the cell surface in secretory vesicles, and because the traffic of such vesicles to the cell surface is normally rapid (Novick et al, 1981;Pastor et al, 1982;Novick and Schekman, 1983), it seems that in the absence of additional mechanisms, the synthesis of such a protein at a specific time in the cell cycle would automatically determine its incorporation into the membrane or wall in a specific pattern.…”

Section: Mechanisms For Localized Incorporation Of Cell Surface Proteinsmentioning

confidence: 99%

Role of Cell Cycle-regulated Expression in the Localized Incorporation of Cell Wall Proteins in Yeast

Smits

Schenkman

Brul

et al. 2006

MBoC

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The yeast cell wall is an essential organelle that protects the cell from mechanical damage and antimicrobial peptides, participates in cell recognition and adhesion, and is important for the generation and maintenance of normal cell shape. We studied the localization of three covalently bound cell wall proteins in Saccharomyces cerevisiae. Tip1p was found only in mother cells, whereas Cwp2p was incorporated in small-to-medium-sized buds. When the promoter regions of TIP1 and CWP2 (responsible for transcription in early G 1 and S/G 2 phases, respectively) were exchanged, the localization patterns of Tip1p and Cwp2p were reversed, indicating that the localization of cell wall proteins can be completely determined by the timing of transcription during the cell cycle. The third protein, Cwp1p, was incorporated into the birth scar, where it remained for several generations. However, we could not detect any role of Cwp1p in strengthening the birth scar wall or any functional interaction with the proteins that mark the birth scar pole as a potential future budding site. Promoter-exchange experiments showed that expression in S/G 2 phase is necessary but not sufficient for the normal localization of Cwp1p. Studies of mutants in which septum formation is perturbed indicate that the normal asymmetric localization of Cwp1p also depends on the normal timing of septum formation, composition of the septum, or both. INTRODUCTIONThe establishment and maintenance of asymmetry are of vital importance for the growth, differentiation, and morphogenesis of cells and organisms. For example, the yeast Saccharomyces cerevisiae grows asymmetrically, producing a bud that becomes the daughter cell (reviewed by Lew and Reed, 1995; Pruyne and Bretscher 2000a,b). In the G 1 phase of the cell cycle, a bud site is selected in a mating type-dependent manner. After the cell cycle-commitment point START, proteins required for bud initiation are recruited to this site, and a bud is formed in a process that depends largely on the delivery of vesicles containing new cell surface material by the polarized actin cytoskeleton. Growth occurs exclusively in the bud, first preferentially at the tip and later isotropically, until the time of cytokinesis. The actin cytoskeleton and cell surface growth are then redirected toward the mother-bud neck, where a chitinous primary septum is formed, followed by the deposition of secondary septa on both sides of the primary septum. Cells then separate by partial digestion of the primary septum, and a new cell cycle is initiated.The cell wall of yeast is essential for growth and is involved in the establishment and maintenance of asymmetry, as illustrated by the loss of both buds and polarized localization of cytoskeletal proteins when the cell wall is removed (Reck-Peterson et al., 1999). The cell wall is comprised of glucans, mannoproteins, and a small amount of chitin (reviewed by Orlean, 1997;Smits et al., 2001;Klis et al., 2006). The mannoproteins can be divided into four classes: 1) noncovalently linked prote...

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“…Polarized growth in the yeast Saccharomyces cerevisiae occurs in response to both internal and external signals, resulting in different morphological structures (2)(3)(4)(5). The mechanics of cell polarity initiation during the mitotic cell cycle can be divided into three sequential phases: (i) nonrandom bud site selection; (ii) organization of proteins at the bud site; and (iii) bud emergence and polarized growth.…”

mentioning

confidence: 99%

Analysis of the Mechanisms of Action of the Saccharomyces cerevisiae Dominant Lethal cdc42 G12V and Dominant Negative cdc42 D118A Mutations

Davis

Richman

Deliduka

et al. 1998

Journal of Biological Chemistry

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The Saccharomyces cerevisiae Cdc42p GTPase is localized to the plasma membrane and involved in signal transduction mechanisms controlling cell polarity. The mechanisms of action of the dominant negative cdc42 D118A mutant and the lethal, gain of function cdc42 G12V mutant were examined. Cdc42 D118A,C188S p and its guanine-nucleotide exchange factor Cdc24p displayed a temperature-dependent interaction in the twohybrid system, which correlated with the temperature dependence of the cdc42 D118A phenotype and supported a Cdc24p sequestration model for the mechanism of cdc42 D118A action. Five cdc42 mutations were isolated that led to decreased interactions with Cdc24p. The isolation of one mutation (V44A) correlated with the observations that the T35A effector domain mutation could interfere with Cdc42 D118A,C188S p-Cdc24p interactions and could suppress the cdc42 D118A mutation, suggesting that Cdc24p may interact with Cdc42p through its effector domain. The cdc42 G12V mutant phenotypes were suppressed by the intragenic T35A and K183-187Q mutations and in skm1⌬ and cla4⌬ cells but not ste20⌬ cells, suggesting that the mechanism of cdc42 G12V action is through the Skm1p and Cla4p protein kinases at the plasma membrane. Two intragenic suppressors of cdc42 G12V were also identified that displayed a dominant negative phenotype at 16°C, which was not suppressed by overexpression of Cdc24p, suggesting an alternate mechanism of action for these dominant negative mutations.The establishment of cell polarity is crucial for the control of many cellular and developmental processes, such as the generation of cell shape, the intracellular movement of organelles, and the secretion and deposition of new cell surface constituents (1). Polarized growth in the yeast Saccharomyces cerevisiae occurs in response to both internal and external signals, resulting in different morphological structures (2-5). The mechanics of cell polarity initiation during the mitotic cell cycle can be divided into three sequential phases: (i) nonrandom bud site selection; (ii) organization of proteins at the bud site; and (iii) bud emergence and polarized growth. Genetic and biochemical studies have identified over 25 proteins, including several GTPases and components of the actin cytoskeleton, that are involved in the regulation of the cell polarity pathway in S. cerevisiae (1, 6, 7).At least six members of the Ras superfamily of GTPases (Rsr1p/Bud1p, Cdc42p, Rho1p, Rho2p, Rho3p, and Rho4p) are involved in controlling cell polarity in S. cerevisiae. These proteins are active when in the GTP-bound state and inactive in the GDP-bound state (8, 9). The activity of these GTPases is controlled by regulatory proteins, such as guanine-nucleotide exchange factors, GTPase-activating proteins, and guanine-nucleotide dissociation inhibitors, as well as by the intracellular localization of the GTPase. Rsr1p/Bud1p is a member of the Ras subfamily and is responsible for bud site selection at one of the two cell poles, but it is not required for bud emergence or polari...

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Establishment of Cell Polarity in Yeast

Cited by 167 publications

References 107 publications

A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous FungusAshbya gossypii

A Ras-like GTPase Is Involved in Hyphal Growth Guidance in the Filamentous FungusAshbya gossypii

Role of Cell Cycle-regulated Expression in the Localized Incorporation of Cell Wall Proteins in Yeast

Analysis of the Mechanisms of Action of the Saccharomyces cerevisiae Dominant Lethal cdc42 G12V and Dominant Negative cdc42 D118A Mutations

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