Distinct Roles for Two Gα–Gβ Interfaces in Cell Polarity Control by a Yeast Heterotrimeric G Protein

Strickfaden, Shelly Catherine; Pryciak, Peter M.

doi:10.1091/mbc.e07-04-0385

Cited by 30 publications

(27 citation statements)

References 91 publications

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“…Gbc cannot report the position of active receptor until it releases from the chemotropic complex and binds inactive Ga. Conversely, the chemotropic complexes can move away from the growth site, blind to local Gbc density, as long as they remain intact. Interestingly, mutations that disrupt the interaction of Gb with the N-terminal interface of Ga, or prevent inactivation of Ga, also implicate G-protein cycling in chemotropic shmooing (Strickfaden and Pryciak, 2008). We infer that by increasing the rate at which the position of the activated receptor is reported, the Ga-GDP/GTP and the Gb-phosphorylation/dephosphorylation cycles strengthen the indirect link between the receptor and the chemotropic complex, and consequently influence the position of the polarity proteins.…”

Section: Role Of Gb Phosphorylation In Receptor Communication To Actimentioning

confidence: 83%

“…Moreover, Ga itself has been implicated in chemotropism (Strickfaden and Pryciak, 2008;Yu et al, 2008). We therefore asked whether Ga DSD bud1D cells can shmoo.…”

Section: Ga Plays An Essential Role In the Chemotropic Shmoo Pathwaymentioning

confidence: 99%

“…More recently, we discovered that the activated forms of the mating-specific Ga protein and the Fus3 MAPK interact directly. A mutant form of Ga that is severely defective in binding Fus3, Ga DSD (Ga-Docking Site Disrupted; previously Ga K21E R22E ), confers a defect in partner discrimination, indicating a problem in directional sensing and/or directed growth (Metodiev et al, 2002;Strickfaden and Pryciak, 2008;Yu et al, 2008). Ga DSD also results in hypophosphorylation and reduced levels of Gb, as does fus3D.…”

Section: Introductionmentioning

confidence: 99%

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Gβ phosphorylation is critical for efficient chemotropism in yeast

DeFlorio¹,

Brett²,

Waszczak³

et al. 2013

Journal of Cell Science

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SummaryMating yeast cells interpret complex pheromone gradients and polarize their growth in the direction of the closest partner. Chemotropic growth depends on both the pheromone receptor and its associated G-protein. Upon activation by the receptor, Ga dissociates from Gbc and Gb is subsequently phosphorylated. Free Gbc signals to the nucleus via a MAPK cascade and recruits Far1-Cdc24 to the incipient growth site. It is not clear how the cell establishes and stabilizes the axis of polarity, but this process is thought to require local signal amplification via the Gbc-Far1-Cdc24 chemotropic complex, as well as communication between this complex and the activated receptor. Here we show that a mutant form of Gb that cannot be phosphorylated confers defects in directional sensing and chemotropic growth. Our data suggest that phosphorylation of Gb plays a role in localized signal amplification and in the dynamic communication between the receptor and the chemotropic complex, which underlie growth site selection and maintenance.

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Section: Role Of Gb Phosphorylation In Receptor Communication To Actimentioning

confidence: 83%

“…Moreover, Ga itself has been implicated in chemotropism (Strickfaden and Pryciak, 2008;Yu et al, 2008). We therefore asked whether Ga DSD bud1D cells can shmoo.…”

Section: Ga Plays An Essential Role In the Chemotropic Shmoo Pathwaymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gβ phosphorylation is critical for efficient chemotropism in yeast

DeFlorio¹,

Brett²,

Waszczak³

et al. 2013

Journal of Cell Science

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“…The following plasmids were a gift from Peter Pryciak: 2m HIS3 pGAL1-STE12 (Strickfaden and Pryciak 2008), CEN TRP1 pGAL1-STE11-Cpr (Strickfaden et al 2007), CEN TRP1 pGAL1-GST-Ste11DN (Moskow et al 2000), CEN URA3 STE5-GFPx3 (Strickfaden et al 2007), CEN URA3 pGAL1-STE5 Q59L (Winters et al 2005), and CEN TRP1 pGAL1-STE5DN-CTM (Pryciak and Huntress 1998). The following plasmid was a gift from Jeremy Thorner: CEN LEU2 pGAL1-GST-GFP-PH PLCd (Winters et al 2005;Garrenton et al 2010).…”

Section: Strains Media and Miscellaneous Microbial Techniquesmentioning

confidence: 99%

The Putative Lipid Transporter, Arv1, Is Required for Activating Pheromone-Induced MAP Kinase Signaling in Saccharomyces cerevisiae

2011

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Saccharomyces cerevisiae haploid cells respond to extrinsic mating signals by forming polarized projections (shmoos), which are necessary for conjugation. We have examined the role of the putative lipid transporter, Arv1, in yeast mating, particularly the conserved Arv1 homology domain (AHD) within Arv1 and its role in this process. Previously it was shown that arv1 cells harbor defects in sphingolipid and glycosylphosphatidylinositol (GPI) biosyntheses and may harbor sterol trafficking defects. Here we demonstrate that arv1 cells are mating defective and cannot form shmoos. They lack the ability to initiate pheromone-induced G1 cell cycle arrest, due to failure to polarize PI(4,5)P 2 and the Ste5 scaffold, which results in weakened MAP kinase signaling activity. A mutant Ste5, Ste5 Q59L, which binds more tightly to the plasma membrane, suppresses the MAP kinase signaling defects of arv1 cells. Filipin staining shows arv1 cells contain altered levels of various sterol microdomains that persist throughout the mating process. Data suggest that the sterol trafficking defects of arv1 affect PI(4,5)P 2 polarization, which causes a mislocalization of Ste5, resulting in defective MAP kinase signaling and the inability to mate. Importantly, our studies show that the AHD of Arv1 is required for mating, pheromone-induced G1 cell cycle arrest, and for sterol trafficking.

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“…In yeast, bilateral mating defects are often associated with polarity defects, and S. cerevisiae gpa1 mutants are abnormal in polarized growth since they are responding to a nonlocalized, internally generated signal (17,43). Recent evidence suggests that a constitutively activated MAP kinase cascade does not generate proper polarity signals in yeast in the absence of Gpa1p (56). The bilateral mating defect of the gpa2 gpa3 mutant of C. neoformans may result from the failure to polarize properly, and the reduction to 5% of the wild-type level of mating in the G␣ mutant of K. lactis is also consistent with a polarity defect.…”

Section: Fig 3 No Genes Inmentioning

confidence: 99%

Heterotrimeric G-Protein Subunit Function in Candida albicans : both the α and β Subunits of the Pheromone Response G Protein Are Required for Mating

2008

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A pheromone-mediated signaling pathway that couples seven-transmembrane-domain (7-TMD) receptors to a mitogen-activated protein kinase module controls Candida albicans mating. 7-TMD receptors are typically connected to heterotrimeric G proteins whose activation regulates downstream effectors. Two G␣ subunits in C. albicans have been identified previously, both of which have been implicated in aspects of pheromone response. Cag1p was found to complement the mating pathway function of the pheromone receptor-coupled G␣ subunit in Saccharomyces cerevisiae, and Gpa2p was shown to have a role in the regulation of cyclic AMP signaling in C. albicans and to repress pheromone-mediated arrest. Here, we show that the disruption of CAG1 prevented mating, inactivated pheromone-mediated arrest and morphological changes, and blocked pheromone-mediated gene expression changes in opaque cells of C. albicans and that the overproduction of CAG1 suppressed the hyperactive cell cycle arrest exhibited by sst2 mutant cells. Because the disruption of the STE4 homolog constituting the only C. albicans gene for a heterotrimeric G␤ subunit also blocked mating and pheromone response, it appears that in this fungal pathogen the G␣ and G␤ subunits do not act antagonistically but, instead, are both required for the transmission of the mating signal.Many fungi have well-defined mating systems. Currently, the most thoroughly studied is that of the baker's or brewer's yeast Saccharomyces cerevisiae (2,12). In this yeast, a signaling pathway has been elucidated that contains cell type-specific receptors of the seven-transmembrane-domain class that are activated by cell type-specific pheromones (7, 46). The pheromone-bound receptor in turn activates a heterotrimeric G protein (17,43,61). In contrast to many of the related G-protein-linked receptor signaling pathways identified in mammalian systems that use the activated ␣ subunit to transfer the signal to the next step in the signaling cascade, the yeast pathway uses the ␤␥ subunit as the positive activator of downstream functions (61). The role of the free ␤␥ subunit is to bind the Ste5p scaffold protein (63) and the Ste20p p21-activated kinase (35) and trigger localization to the plasma membrane (50), as well as to direct polarized growth by binding the Far1p scaffold (8). The association of the Ste5p scaffold with the membrane (20, 21) ultimately turns on a mitogen-activated protein (MAP) kinase cascade, and the targets of the MAP kinase include critical elements in the mating response (14,22,33,58).In the yeast pathway, the G␣ subunit serves a role primarily in downregulating the signaling pathway. In its GDP-bound state, it associates with and inactivates the signaling ␤␥ subunit; the absence of Gpa1p leads to constitutive signaling and cell cycle arrest (17, 43) and, thus, to haploid-specific lethality (6). This genetic behavior is consistent with the predicted biochemical G-protein cycle; in the off state, the subunits are associated and inactive, while when activated, ␣ and ␤␥ have a relax...

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Distinct Roles for Two Gα–Gβ Interfaces in Cell Polarity Control by a Yeast Heterotrimeric G Protein

Cited by 30 publications

References 91 publications

Gβ phosphorylation is critical for efficient chemotropism in yeast

Gβ phosphorylation is critical for efficient chemotropism in yeast

The Putative Lipid Transporter, Arv1, Is Required for Activating Pheromone-Induced MAP Kinase Signaling in Saccharomyces cerevisiae

Heterotrimeric G-Protein Subunit Function in Candida albicans : both the α and β Subunits of the Pheromone Response G Protein Are Required for Mating

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