Spatial regulation of the guanine nucleotide exchange factor Lte1 in<i>Saccharomyces cerevisiae</i>

Jensen, Sanne; Geymonat, Marco; Johnson, Anthony L.; Segal, Marisa; Johnston, Leland H.

doi:10.1242/jcs.00189

Cited by 60 publications

(72 citation statements)

References 48 publications

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“…Here, we show that deletion of RDI1 suppresses the mitotic exit defect of ⌬lte1 cells at low temperatures, possibly due to Cdc42 activation. Cdc42 regulates exit from mitosis via at least three independent pathways involving the Cdc42 effectors Cla4, Ste20, and Gic1 (Figure 2A) (Hö fken and Schiebel, 2002;Jensen et al, 2002;Seshan et al, 2002;Hö fken and Schiebel, 2004). Previously, we could demonstrate that a temperature-sensitive allele of the Cdc42 GEF CDC24 in a ⌬lte1 background is lethal at all temperatures (Hö fken and Schiebel, 2002).…”

Section: Functions Of Rdi1mentioning

confidence: 88%

“…Cdc42 and its effectors Ste20, Cla4, and Gic1 promote exit from mitosis via at least three independent mechanisms (Hö fken and Schiebel, 2002; Jensen et al, 2002;Seshan et al, 2002;Hö fken and Schiebel, 2004;Bosl and Li 2005) (Figure 2A). The small GTPase Tem1 and its putative GEF Lte1 are the most upstream components of the mitotic exit network, the signaling cascade that controls exit from mitosis (Bosl and Li, 2005).…”

Section: Rdi1 Has a Role In Pseudohyphal Growth And Mitotic Exitmentioning

confidence: 99%

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The Rho GDI Rdi1 Regulates Rho GTPases by Distinct Mechanisms

Tiedje

Sakwa

Just

et al. 2008

MBoC

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The small guanosine triphosphate (GTP)-binding proteins of the Rho family are implicated in various cell functions, including establishment and maintenance of cell polarity. Activity of Rho guanosine triphosphatases (GTPases) is not only regulated by guanine nucleotide exchange factors and GTPase-activating proteins but also by guanine nucleotide dissociation inhibitors (GDIs). These proteins have the ability to extract Rho proteins from membranes and keep them in an inactive cytosolic complex. Here, we show that Rdi1, the sole Rho GDI of the yeast Saccharomyces cerevisiae, contributes to pseudohyphal growth and mitotic exit. Rdi1 interacts only with Cdc42, Rho1, and Rho4, and it regulates these Rho GTPases by distinct mechanisms. Binding between Rdi1 and Cdc42 as well as Rho1 is modulated by the Cdc42 effector and p21-activated kinase Cla4. After membrane extraction mediated by Rdi1, Rho4 is degraded by a novel mechanism, which includes the glycogen synthase kinase 3␤ homologue Ygk3, vacuolar proteases, and the proteasome. Together, these results indicate that Rdi1 uses distinct modes of regulation for different Rho GTPases. INTRODUCTIONSmall guanosine triphosphatases (GTPases) of the Rho family control fundamental processes of cell biology common to all eukaryotes, such as morphogenesis, polarity, movement, and cell division (Jaffe and Hall, 2005). In the budding yeast Saccharomyces cerevisiae, which encodes six Rho GTPases (Cdc42 and Rho1 to Rho5), these proteins play a pivotal role in the establishment of cell polarity (Park and Bi, 2007). Budding yeast cells undergo polarized growth during various phases of their life cycle, including budding during vegetative growth, mating between haploid cells of opposite mating types, and filamentous growth upon nutrient limitation. Although Cdc42 and Rho1 are well characterized, little is known about the other Rho proteins. Membrane association of Rho-type GTPases is essential for their function, and it depends on a C-terminal prenyl moiety and an adjacent polybasic region. Cdc42 localizes to internal membranes and the entire plasma membrane, where it clusters at sites of polarized growth, including the tips of mating projections, incipient bud sites, the tips and sides of growing buds, and the bud neck region of large-budded cells (Ziman et al., 1993;Richman et al., 2002). In addition to membranebound Cdc42, a cytoplasmic pool has been found (Ziman et al., 1993). Similar to Cdc42, Rho1 has been shown to localize at sites of polarized growth .Like other regulatory GTPases, they act as molecular switches, cycling between an active guanosine triphosphate (GTP)-bound state and an inactive guanosine diphosphate (GDP)-bound state. This activity is highly regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). The exchange of GDP to GTP, and thus the activation of Cdc42, is catalyzed by GEFs. In the active GTP-bound state, Rho GTPases perform their regulatory function through a conformation-specific interaction with effector proteins. G...

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Section: Functions Of Rdi1mentioning

confidence: 88%

Section: Rdi1 Has a Role In Pseudohyphal Growth And Mitotic Exitmentioning

confidence: 99%

The Rho GDI Rdi1 Regulates Rho GTPases by Distinct Mechanisms

Tiedje

Sakwa

Just

et al. 2008

MBoC

View full text Add to dashboard Cite

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“…A small Ras-like Tem1 GTPase (Geymonat et al, 2002) and its two-component GAPs, Bfa1 and Bub2 (Geymonat et al, 2003), are present at the cytoplasmic side of the SPB that migrates into the bud, whereas Tem1's GTP/GDP exchange factor Lte1 localizes to the bud cortex (Bardin et al, 2000;Pereira et al, 2000). Lte1 localization to the bud cortex is promoted by Cdk1 and Cla4, whereas Lte1 dissociation from the bud cortex is promoted by Cdc14 (Hofken and Schiebel, 2002;Jensen et al, 2002a), perhaps in a positive feedback loop. Thus, this spatial separation prevents Tem1 activation until after the SPB enters the bud (Bardin et al, 2000;Pereira et al, 2000).…”

Section: Fear and Mitotic Exitmentioning

confidence: 99%

Yeast polo-like kinases: functionally conserved multitask mitotic regulators

et al. 2005

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The polo-like kinases (Plks) are a conserved subfamily of Ser/Thr protein kinases that play pivotal roles in regulating various cellular and biochemical events at multiple stages of M phase. Genetic and biochemical data revealed that both the budding yeast and the fission yeast polo kinase homologs (Cdc5 and Plo1, respectively) bear remarkable functional similarities with those in metazoan organisms, suggesting that the role of Plks is largely conserved throughout evolution. Thus, studies on Plks in genetically amenable lower eucaryotic organisms may yield valuable insights into the function of Plks in higher eucaryotic organisms. In this review, common properties and distinct functions of Cdc5 and Plo1 will be discussed and compared to properties and functions of Plks in higher eucaryotic organisms.

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“…Lte1p localization (which is regulated via phosphorylation, Ref. 9) is normally confined to buds growing from secretory activity, at least in part by virtue of interactions with plasma membrane-associated Ras2p (10) and perhaps by being bound to other cell polarity proteins in the bud such as Kel1p and Kel2p (14). Even so, we found it surprising to discover lte1 in a screen revealing secretory protein processing mutants.…”

mentioning

confidence: 91%

“…Lte1p is a positive regulator of Tem1p function (7) and overexpression of TEM1 rescues the cold-sensitive growth arrest of lte1 cells (8). Lte1p has a large, modular-appearing primary structure including small GEF homology domains embedded in the C-and N-terminal regions (9). Overexpression of lte1-mini (truncated to lack these domains) can suppress the cold-sensitive growth arrest of lte1D cells, raising the possibility that Lte1p might not be a GEF for Tem1p (10); however, other analysis supports the hypothesis that GEF function of Lte1p activates Tem1p (11).…”

mentioning

confidence: 99%

A Role For Lte1p (a Low Temperature Essential Protein Involved in Mitosis) in Proprotein Processing in the Yeast Secretory Pathway

Zhao

Chang

Toh‐e

et al. 2007

Journal of Biological Chemistry

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We previously identified six single gene disruptions in Saccharomyces cerevisiae that allow enhanced immunoreactive insulin secretion primarily because of defective Kex2p-mediated endoproteolytic processing. Five eis mutants disrupted established VPS (vacuolar protein sorting) genes, The sixth, LTE1, is a Low Temperature (<15°C) Essential gene encoding a large protein with potential guanine nucleotide exchange (GEF) domains. Lte1p functions as a positive regulator of the mitotic GTPase Tem1p, and overexpression of Tem1p suppresses the low temperature mitotic defect of lte1. By sequence analysis, Tem1p has highest similarity to Vps21p (yeast homolog of mammalian Rab5). Unlike TEM1, LTE1 is not restricted to mitosis but is expressed throughout the cell cycle. Lte1p function in interphase cells is largely unknown. Here we confirm the eis phenotype of lte1 mutant cells and demonstrate a defect in proalpha factor processing that is rescued by expression of fulllength Lte1p but not a C-terminally truncated Lte1p lacking its GEF homology domain. Neither overexpression of Tem1p nor 13 other structurally related GTPases can suppress the secretory proprotein processing defect. However, overexpression of Vps21p selectively restores proprotein processing in a manner dependent upon the active GTP-bound form of the GTPase. By contrast, a vps21 mutant produces a synthetic defect with lte1 in proprotein processing, as well as a synthetic growth defect. Together, the data underscore a link between the mitotic regulator, Lte1p, and protein processing and trafficking in the secretory/endosomal system.

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Spatial regulation of the guanine nucleotide exchange factor Lte1 inSaccharomyces cerevisiae

Cited by 60 publications

References 48 publications

The Rho GDI Rdi1 Regulates Rho GTPases by Distinct Mechanisms

The Rho GDI Rdi1 Regulates Rho GTPases by Distinct Mechanisms

Yeast polo-like kinases: functionally conserved multitask mitotic regulators

A Role For Lte1p (a Low Temperature Essential Protein Involved in Mitosis) in Proprotein Processing in the Yeast Secretory Pathway

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