scholarly journals Ubiquitin-mediated Targeting of a Mutant Plasma Membrane ATPase, Pma1-7, to the Endosomal/Vacuolar System in Yeast

2004 ◽  
Vol 15 (5) ◽  
pp. 2401-2409 ◽  
Author(s):  
Maddalena Pizzirusso ◽  
Amy Chang
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Plasma Membrane Atpase ◽  
Membrane Atpase ◽  
Endosomal Pathway ◽  
Quality Control Mechanism ◽  
Vacuolar System

Pma1-7 is a mutant plasma membrane ATPase that is impaired in targeting to the cell surface at 37°C and is delivered instead to the endosomal/vacuolar pathway for degradation. We have proposed that Pma1-7 is a substrate for a Golgibased quality control mechanism. By contrast with wild-type Pma1, Pma1-7 is ubiquitinated. Ubiquitination and endosomal targeting of Pma1-7 is dependent on the Rsp5-Bul1-Bul2 ubiquitin ligase protein complex but not the transmembrane ubiquitin ligase Tul1. Analysis of Pma1-7 ubiquitination in mutants blocked in protein transport at various steps of the secretory pathway suggests that ubiquitination occurs after ER exit but before endosomal entry. In the absence of ubiquitination in rsp5-1 cells, Pma1-7 is delivered to the cell surface and remains stable. Nevertheless, Pma1-7 remains impaired in association with detergent-insoluble glycolipid-enriched complexes in rsp5-1 cells, suggesting that ubiquitination is not the cause of Pma1-7 exclusion from rafts. In vps1 cells in which protein transport into the endosomal pathway is blocked, Pma1-7 is routed to the cell surface. On arrival at the plasma membrane in vps1 cells, Pma1-7 remains stable and its ubiquitination disappears, suggesting deubiquitination activity at the cell surface. We suggest that Pma1-7 sorting and fate are regulated by ubiquitination.

scholarly journals An Endosome-to-Plasma Membrane Pathway Involved in Trafficking of a Mutant Plasma Membrane ATPase in Yeast

2000 ◽  
Vol 11 (2) ◽  
pp. 579-592 ◽  
Author(s):  
Wen-jie Luo ◽  
Amy Chang
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Secretory Pathway ◽  
Protein Sorting ◽  
Temperature Sensitive ◽  
Plasma Membrane Atpase ◽  
Vacuolar Protein Sorting ◽  
Membrane Atpase ◽  
Vacuolar Protein ◽  
Endosomal System

The plasma membrane ATPase, encoded by PMA1, is delivered to the cell surface via the secretory pathway. Previously, we characterized a temperature-sensitive pma1 mutant in which newly synthesized Pma1-7 is not delivered to the plasma membrane but is mislocalized instead to the vacuole at 37°C. Severalvps mutants, which are defective in vacuolar protein sorting, suppress targeting-defective pma1 by allowing mutant Pma1 to move once again to the plasma membrane. In this study, we have analyzed trafficking in the endosomal system by monitoring the movement of Pma1-7 in vps36, vps1, andvps8 mutants. Upon induction of expression, mutant Pma1 accumulates in the prevacuolar compartment in vps36cells. After chase, a fraction of newly synthesized Pma1-7 is delivered to the plasma membrane. In both vps1 andvps8 cells, newly synthesized mutant Pma1 appears in small punctate structures before arrival at the cell surface. Nevertheless, biosynthetic membrane traffic appears to follow different routes in vps8 and vps1: the vacuolar protein-sorting receptor Vps10p is stable in vps8 but not in vps1. Furthermore, a defect in endocytic delivery to the vacuole was revealed in vps8 (andvps36) but not vps1 by endocytosis of the bulk membrane marker FM 4-64. Moreover, in vps8 cells, there is defective down-regulation from the cell surface of the mating receptor Ste3, consistent with persistent receptor recycling from an endosomal compartment to the plasma membrane. These data support a model in which mutant Pma1 is diverted from the Golgi to the surface invps1 cells. We hypothesize that in vps8and vps36, in contrast to vps1, mutant Pma1 moves to the surface via endosomal intermediates, implicating an endosome-to-surface traffic pathway.

scholarly journals Secretory vesicles externalize the major plasma membrane ATPase in yeast.

1988 ◽  
Vol 106 (3) ◽  
pp. 641-648 ◽  
Author(s):  
C L Holcomb ◽  
W J Hansen ◽  
T Etcheverry ◽  
R Schekman
Keyword(s):  
Plasma Membrane ◽  
Secretory Pathway ◽  
Biochemical Characterization ◽  
Plasma Membrane Atpase ◽  
Membrane Assembly ◽  
Yeast Cell Surface ◽  
Membrane Atpase ◽  
Constitutive Secretion ◽  
Secretory Enzyme

Yeast cell surface growth is accomplished by constitutive secretion and plasma membrane assembly, culminating in the fusion of vesicles with the bud membrane. Coordination of secretion and membrane assembly has been investigated by examining the biogenesis of plasma membrane ATPase (PM ATPase) in secretion-defective (sec) strains of Saccharomyces cerevisiae. PM ATPase is synthesized as a approximately 106-kD polypeptide that is not detectably modified by asparagine-linked glycosylation or proteolysis during transit to the plasma membrane. Export of the PM ATPase requires the secretory pathway. In sec1, a mutant defective in the last step of secretion, large amounts of Golgi-derived vesicles are accumulated. Biochemical characterization of this organelle has demonstrated that PM ATPase and the secretory enzyme, acid phosphatase, are transported in a single vesicle species.

scholarly journals Plant Proton Pumps and Cytosolic pH-Homeostasis

2021 ◽  
Vol 12 ◽  
Author(s):  
Maike Cosse ◽  
Thorsten Seidel
Keyword(s):  
Plasma Membrane ◽  
Secretory Pathway ◽  
Coordination Mechanisms ◽  
Proton Pumps ◽  
Plasma Membrane Atpase ◽  
Ph Homeostasis ◽  
Secondary Active Transport ◽  
Cytosolic Ph ◽  
Ion Concentrations ◽  
Membrane Atpase

Proton pumps create a proton motif force and thus, energize secondary active transport at the plasma nmembrane and endomembranes of the secretory pathway. In the plant cell, the dominant proton pumps are the plasma membrane ATPase, the vacuolar pyrophosphatase (V-PPase), and the vacuolar-type ATPase (V-ATPase). All these pumps act on the cytosolic pH by pumping protons into the lumen of compartments or into the apoplast. To maintain the typical pH and thus, the functionality of the cytosol, the activity of the pumps needs to be coordinated and adjusted to the actual needs. The cellular toolbox for a coordinated regulation comprises 14-3-3 proteins, phosphorylation events, ion concentrations, and redox-conditions. This review combines the knowledge on regulation of the different proton pumps and highlights possible coordination mechanisms.

scholarly journals Chs6p-dependent Anterograde Transport of Chs3p from the Chitosome to the Plasma Membrane inSaccharomyces cerevisiae

1998 ◽  
Vol 9 (6) ◽  
pp. 1565-1576 ◽  
Author(s):  
Michael Ziman ◽  
John S. Chuang ◽  
Michael Tsung ◽  
Susan Hamamoto ◽  
Randy Schekman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Cell Separation ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Subcellular Fractionation ◽  
Chitin Synthase ◽  
Anterograde Transport ◽  
Membrane Compartment

Chitin synthase III (CSIII), an enzyme required to form a chitin ring in the nascent division septum of Saccharomyces cerevisiae, may be transported to the cell surface in a regulated manner. Chs3p, the catalytic subunit of CSIII, requires the product of CHS6 to be transported to or activated at the cell surface. We find that chs6Δ strains have morphological abnormalities similar to those of chs3mutants. Subcellular fractionation and indirect immunofluorescence indicate that Chs3p distribution is altered in chs6mutant cells. Order-of-function experiments usingend4–1 (endocytosis-defective) and chs6mutants indicate that Chs6p is required for anterograde transport of Chs3p from an internal endosome-like membrane compartment, the chitosome, to the plasma membrane. As a result, chs6strains accumulate Chs3p in chitosomes. Chs1p, a distinct chitin synthase that acts during or after cell separation, is transported normally in chs6 mutants, suggesting that Chs1p and Chs3p are independently packaged during protein transport through the late secretory pathway.

scholarly journals Lst1p and Sec24p Cooperate in Sorting of the Plasma Membrane Atpase into Copii Vesicles in Saccharomyces cerevisiae

2000 ◽  
Vol 151 (5) ◽  
pp. 973-984 ◽  
Author(s):  
Yuval Shimoni ◽  
Tatsuo Kurihara ◽  
Mariella Ravazzola ◽  
Mylène Amherdt ◽  
Lelio Orci ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasma Membrane ◽  
Protein Transport ◽  
Buoyant Density ◽  
Small Gtpase ◽  
Plasma Membrane Atpase ◽  
Vesicle Budding ◽  
Transport Vesicles ◽  
Membrane Atpase ◽  
Copii Vesicles

Formation of ER-derived protein transport vesicles requires three cytosolic components, a small GTPase, Sar1p, and two heterodimeric complexes, Sec23/24p and Sec13/31p, which comprise the COPII coat. We investigated the role of Lst1p, a Sec24p homologue, in cargo recruitment into COPII vesicles in Saccharomyces cerevisiae. A tagged version of Lst1p was purified and eluted as a heterodimer complexed with Sec23p comparable to the Sec23/24p heterodimer. We found that cytosol from an lst1-null strain supported the packaging of α-factor precursor into COPII vesicles but was deficient in the packaging of Pma1p, the essential plasma membrane ATPase. Supplementation of mutant cytosol with purified Sec23/Lst1p restored Pma1p packaging into the vesicles. When purified COPII components were used in the vesicle budding reaction, Pma1p packaging was optimal with a mixture of Sec23/24p and Sec23/Lst1p; Sec23/Lst1p did not replace Sec23/24p. Furthermore, Pma1p coimmunoprecipitated with Lst1p and Sec24p from vesicles. Vesicles formed with a mixture of Sec23/Lst1p and Sec23/24p were similar morphologically and in their buoyant density, but larger than normal COPII vesicles (87-nm vs. 75-nm diameter). Immunoelectronmicroscopic and biochemical studies revealed both Sec23/Lst1p and Sec23/24p on the membranes of the same vesicles. These results suggest that Lst1p and Sec24p cooperate in the packaging of Pma1p and support the view that biosynthetic precursors of plasma membrane proteins must be sorted into ER-derived transport vesicles. Sec24p homologues may comprise a more complex coat whose combinatorial subunit composition serves to expand the range of cargo to be packaged into COPII vesicles. By changing the geometry of COPII coat polymerization, Lst1p may allow the transport of bulky cargo molecules, polymers, or particles.

scholarly journals Synthesis of Sphingolipids with Very Long Chain Fatty Acids but Not Ergosterol Is Required for Routing of Newly Synthesized Plasma Membrane ATPase to the Cell Surface of Yeast

2005 ◽  
Vol 280 (23) ◽  
pp. 22515-22522 ◽  
Author(s):  
Barbara Gaigg ◽  
Birgit Timischl ◽  
Linda Corbino ◽  
Roger Schneiter
Keyword(s):  
Plasma Membrane ◽  
Fatty Acid ◽  
Cell Surface ◽  
Secretory Pathway ◽  
Chain Fatty Acid ◽  
Proton Pumping ◽  
Sterol Synthesis ◽  
Plasma Membrane Atpase ◽  
Long Chain Fatty Acid ◽  
Long Chain

The proton pumping H+-ATPase, Pma1p, is an abundant and very long-lived polytopic protein of the Saccharomyces cerevisiae plasma membrane. Pma1p constitutes a major cargo of the secretory pathway and thus serves as an excellent model to study plasma membrane biogenesis. We have previously shown that newly synthesized Pma1p is mistargeted to the vacuole in an elo3Δ mutant that affects the synthesis of the ceramide-bound C26 very long chain fatty acid (Eisenkolb, M., Zenzmaier, C., Leitner, E., and Schneiter, R. (2002) Mol. Biol. Cell 13, 4414–4428) and now describe a more detailed analysis of the role of lipids in Pma1p biogenesis. Remarkably, a block at various steps of sterol biosynthesis, a complete block in sterol synthesis, or the substitution of internally synthesized ergosterol by externally supplied ergosterol or even by cholesterol does not affect Pma1p biogenesis or its association with detergent-resistant membrane domains (lipid “rafts”). However, a block in sphingolipid synthesis or any perturbation in the synthesis of the ceramide-bound C26 very long chain fatty acid results in mistargeting of newly synthesized Pma1p to the vacuole. Mistargeting correlates with a lack of newly synthesized Pma1p to acquire detergent resistance, suggesting that sphingolipids with very long acyl chains affect sorting of Pma1p to the cell surface.

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