scholarly journals mRNAs Encoding Polarity and Exocytosis Factors Are Cotransported with the Cortical Endoplasmic Reticulum to the Incipient Bud in Saccharomyces cerevisiae

2007 ◽  
Vol 27 (9) ◽  
pp. 3441-3455 ◽  
Author(s):  
Stella Aronov ◽  
Rita Gelin-Licht ◽  
Gadi Zipor ◽  
Liora Haim ◽  
Einat Safran ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Nuclear Division ◽  
Mrna Localization ◽  
Dependent Manner ◽  
Protein Enrichment ◽  
Bud Emergence ◽  
Bud Site ◽  
Cortical Endoplasmic Reticulum ◽  
Asymmetrically Distributed

ABSTRACT Polarized growth in the budding yeast Saccharomyces cerevisiae depends upon the asymmetric localization and enrichment of polarity and secretion factors at the membrane prior to budding. We examined how these factors (i.e., Cdc42, Sec4, and Sro7) reach the bud site and found that their respective mRNAs localize to the tip of the incipient bud prior to nuclear division. Asymmetric mRNA localization depends upon factors that facilitate ASH1 mRNA localization (e.g., the 3′ untranslated region, She proteins 1 to 5, Puf6, actin cytoskeleton, and a physical association with She2). mRNA placement precedes protein enrichment and subsequent bud emergence, implying that mRNA localization contributes to polarization. Correspondingly, mRNAs encoding proteins which are not asymmetrically distributed (i.e., Snc1, Mso1, Tub1, Pex3, and Oxa1) are not polarized. Finally, mutations which affect cortical endoplasmic reticulum (ER) entry and anchoring in the bud (myo4Δ, sec3Δ, and srp101) also affect asymmetric mRNA localization. Bud-localized mRNAs, including ASH1, were found to cofractionate with ER microsomes in a She2- and Sec3-dependent manner; thus, asymmetric mRNA transport and cortical ER inheritance are connected processes in yeast.

scholarly journals Sensing a bud in the yeast morphogenesis checkpoint: a role for Elm1

2016 ◽  
Vol 27 (11) ◽  
pp. 1764-1775 ◽  
Author(s):  
Hui Kang ◽  
Denis Tsygankov ◽  
Daniel J. Lew
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Division ◽  
Environmental Stresses ◽  
Bud Formation ◽  
Septin Ring ◽  
Bud Emergence ◽  
Bud Neck ◽  
Morphogenesis Checkpoint ◽  
Bud Site ◽  
Mitotic Inhibitor

Bud formation by Saccharomyces cerevisiae must be coordinated with the nuclear cycle to enable successful proliferation. Many environmental stresses temporarily disrupt bud formation, and in such circumstances, the morphogenesis checkpoint halts nuclear division until bud formation can resume. Bud emergence is essential for degradation of the mitotic inhibitor, Swe1. Swe1 is localized to the septin cytoskeleton at the bud neck by the Swe1-binding protein Hsl7. Neck localization of Swe1 is required for Swe1 degradation. Although septins form a ring at the presumptive bud site before bud emergence, Hsl7 is not recruited to the septins until after bud emergence, suggesting that septins and/or Hsl7 respond to a “bud sensor.” Here we show that recruitment of Hsl7 to the septin ring depends on a combination of two septin-binding kinases: Hsl1 and Elm1. We elucidate which domains of these kinases are needed and show that artificial targeting of those domains suffices to recruit Hsl7 to septin rings even in unbudded cells. Moreover, recruitment of Elm1 is responsive to bud emergence. Our findings suggest that Elm1 plays a key role in sensing bud emergence.

scholarly journals Different polarisome components play distinct roles in Slt2p-regulated cortical ER inheritance in Saccharomyces cerevisiae

2013 ◽  
Vol 24 (19) ◽  
pp. 3145-3154 ◽  
Author(s):  
Xia Li ◽  
Susan Ferro-Novick ◽  
Peter Novick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Protein Kinase ◽  
Protein Phosphatase ◽  
Mitogen Activated Protein Kinase ◽  
Common Mechanism ◽  
Late Step ◽  
Mitogen Activated Protein ◽  
Cortical Endoplasmic Reticulum

Ptc1p, a type 2C protein phosphatase, is required for a late step in cortical endoplasmic reticulum (cER) inheritance in Saccharomyces cerevisiae. In ptc1Δ cells, ER tubules migrate from the mother cell and contact the bud tip, yet fail to spread around the bud cortex. This defect results from the failure to inactivate a bud tip–associated pool of the cell wall integrity mitogen-activated protein kinase, Slt2p. Here we report that the polarisome complex affects cER inheritance through its effects on Slt2p, with different components playing distinct roles: Spa2p and Pea2p are required for Slt2p retention at the bud tip, whereas Bni1p, Bud6p, and Sph1p affect the level of Slt2p activation. Depolymerization of actin relieves the ptc1Δ cER inheritance defect, suggesting that in this mutant the ER becomes trapped on the cytoskeleton. Loss of Sec3p also blocks ER inheritance, and, as in ptc1Δ cells, this block is accompanied by activation of Slt2p and is reversed by depolymerization of actin. Our results point to a common mechanism for the regulation of ER inheritance in which Slt2p activity at the bud tip controls the association of the ER with the actin-based cytoskeleton.

Aux1p/Swa2p Is Required for Cortical Endoplasmic Reticulum Inheritance in Saccharomyces cerevisiae

2001 ◽  
Vol 12 (9) ◽  
pp. 2614-2628 ◽  
Author(s):  
Yunrui Du ◽  
Marc Pypaert ◽  
Peter Novick ◽  
Susan Ferro-Novick
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Fluorescent Protein ◽  
Yeast Saccharomyces Cerevisiae ◽  
Bifunctional Protein ◽  
Daughter Cells ◽  
Bud Neck ◽  
J Domain ◽  
Green Fluorescent ◽  
Cortical Endoplasmic Reticulum

In the yeast Saccharomyces cerevisiae, the endoplasmic reticulum (ER) is found at the periphery of the cell and around the nucleus. The segregation of ER through the mother-bud neck may occur by more than one mechanism because perinuclear, but not peripheral ER, requires microtubules for this event. To identify genes whose products are required for cortical ER inheritance, we have used a Tn3-based transposon library to mutagenize cells expressing a green fluorescent protein-tagged ER marker protein (Hmg1p). This approach has revealed that AUX1/SWA2plays a role in ER inheritance. The COOH terminus of Aux1p/Swa2p contains a J-domain that is highly related to the J-domain of auxilin, which stimulates the uncoating of clathrin-coated vesicles. Deletion of the J-domain of Aux1p/Swa2p leads to vacuole fragmentation and membrane accumulation but does not affect the migration of peripheral ER into daughter cells. These findings suggest that Aux1p/Swa2p may be a bifunctional protein with roles in membrane traffic and cortical ER inheritance. In support of this hypothesis, we find that Aux1p/Swa2p localizes to ER membranes.

scholarly journals Alternative Modes of Organellar Segregation during Sporulation in Saccharomyces cerevisiae

2007 ◽  
Vol 6 (11) ◽  
pp. 2009-2017 ◽  
Author(s):  
Yasuyuki Suda ◽  
Hideki Nakanishi ◽  
Erin M. Mathieson ◽  
Aaron M. Neiman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Plasma Membranes ◽  
De Novo ◽  
Leading Edge ◽  
Protein Coat ◽  
Prospore Membrane ◽  
Cortical Endoplasmic Reticulum ◽  
Mitotic Cells

ABSTRACT Formation of ascospores in the yeast Saccharomyces cerevisiae is driven by an unusual cell division in which daughter nuclei are encapsulated within de novo-formed plasma membranes, termed prospore membranes. Generation of viable spores requires that cytoplasmic organelles also be captured along with nuclei. In mitotic cells segregation of mitochondria into the bud requires a polarized actin cytoskeleton. In contrast, genes involved in actin-mediated transport are not essential for sporulation. Instead, efficient segregation of mitochondria into spores requires Ady3p, a component of a protein coat found at the leading edge of the prospore membrane. Other organelles whose mitotic segregation is promoted by actin, such as the vacuole and the cortical endoplasmic reticulum, are not actively segregated during sporulation but are regenerated within spores. These results reveal that organellar segregation into spores is achieved by mechanisms distinct from those in mitotic cells.

scholarly journals Bni5p, a Septin-Interacting Protein, Is Required for Normal Septin Function and Cytokinesis in Saccharomyces cerevisiae

2002 ◽  
Vol 22 (19) ◽  
pp. 6906-6920 ◽  
Author(s):  
Philip R. Lee ◽  
Sukgil Song ◽  
Hyeon-Su Ro ◽  
Chong J. Park ◽  
John Lippincott ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Localization ◽  
Growth Defect ◽  
Dependent Manner ◽  
Interacting Protein ◽  
Growth Defects ◽  
Bud Emergence ◽  
Bud Neck ◽  
And Function

ABSTRACT In the budding yeast Saccharomyces cerevisiae, the Cdc3p, Cdc10p, Cdc11p, Cdc12p, and Sep7p/Shs1p septins assemble early in the cell cycle in a ring that marks the future cytokinetic site. The septins appear to be major structural components of a set of filaments at the mother-bud neck and function as a scaffold for recruiting proteins involved in cytokinesis and other processes. We isolated a novel gene, BNI5, as a dosage suppressor of the cdc12-6 growth defect. Overexpression of BNI5 also suppressed the growth defects of cdc10-1, cdc11-6, and sep7Δ strains. Loss of BNI5 resulted in a cytokinesis defect, as evidenced by the formation of connected cells with shared cytoplasms, and deletion of BNI5 in a cdc3-6, cdc10-1, cdc11-6, cdc12-6, or sep7Δ mutant strain resulted in enhanced defects in septin localization and cytokinesis. Bni5p localizes to the mother-bud neck in a septin-dependent manner shortly after bud emergence and disappears from the neck approximately 2 to 3 min before spindle disassembly. Two-hybrid, in vitro binding, and protein-localization studies suggest that Bni5p interacts with the N-terminal domain of Cdc11p, which also appears to be sufficient for the localization of Cdc11p, its interaction with other septins, and other critical aspects of its function. Our data suggest that the Bni5p-septin interaction is important for septin ring stability and function, which is in turn critical for normal cytokinesis.

scholarly journals Dysferlin Domain-containing Proteins, Pex30p and Pex31p, Localized to Two Compartments, Control the Number and Size of Oleate-induced Peroxisomes in Pichia pastoris

2008 ◽  
Vol 19 (3) ◽  
pp. 885-898 ◽  
Author(s):  
Mingda Yan ◽  
Dorian A. Rachubinski ◽  
Saurabh Joshi ◽  
Richard A. Rachubinski ◽  
Suresh Subramani
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Steady State ◽  
Pichia Pastoris ◽  
Subcellular Localization ◽  
Yarrowia Lipolytica ◽  
Dependent Manner ◽  
Growth Environment ◽  
Dual Localization

Yarrowia lipolytica Pex23p and Saccharomyces cerevisiae Pex30p, Pex31p, and Pex32p comprise a family of dysferlin domain–containing peroxins. We show that the deletion of their Pichia pastoris homologues, PEX30 and PEX31, does not affect the function or division of methanol-induced peroxisomes but results in fewer and enlarged, functional, oleate-induced peroxisomes. Synthesis of Pex30p is constitutive, whereas that of Pex31p is oleate-induced but at a much lower level relative to Pex30p. Pex30p interacts with Pex31p and is required for its stability. At steady state, both Pex30p and Pex31p exhibit a dual localization to the endoplasmic reticulum (ER) and peroxisomes. However, Pex30p is localized mostly to the ER, whereas Pex31p is predominantly on peroxisomes. Consistent with ER-to-peroxisome trafficking of these proteins, Pex30p accumulates on peroxisomes upon overexpression of Pex31p. Additionally, Pex31p colocalizes with Pex30p at the ER in pex19Δ cells and can be chased from the ER to peroxisomes in a Pex19p-dependent manner. The dysferlin domains of Pex30p and Pex31p, which are dispensable for their interaction, stability, and subcellular localization, are essential for normal peroxisome number and size. The growth environment-specific role of these peroxins, their dual localization, and the function of their dysferlin domains provide novel insights into peroxisome morphogenesis.

scholarly journals BED1, a gene encoding a galactosyltransferase homologue, is required for polarized growth and efficient bud emergence in Saccharomyces cerevisiae.

1996 ◽  
Vol 132 (1) ◽  
pp. 137-151 ◽  
Author(s):  
G Mondésert ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Actin Cytoskeleton ◽  
Dependent Manner ◽  
Polarized Growth ◽  
Checkpoint Control ◽  
Wild Type ◽  
Ellipsoidal Shape ◽  
Bud Emergence ◽  
Morphogenesis Checkpoint

The ellipsoidal shape of the yeast Saccharomyces cerevisiae is the result of successive isotropic/apical growth switches that are regulated in a cell cycle-dependent manner. It is thought that growth polarity is governed by the remodeling of the actin cytoskeleton that is itself under the control of the cell cycle machinery. The cell cycle and the morphogenesis cycle are tightly coupled and it has been recently suggested that a morphogenesis/polarity checkpoint control monitors bud emergence in order to maintain the coupling of these two events (Lew, D. J., and S. I. Reed. 1995. J. Cell Biol. 129:739-749). During a screen based on the inability of cells impaired in the budding process to survive when the morphogenesis checkpoint control is abolished, we identified and characterized BED1, a new gene that is required for efficient budding. Cells carrying a disrupted allele of BED1 no longer have the wild-type ellipsoidal shape characteristic of S. cerevisiae, are larger than wild-type cells, are deficient in bud emergence, and depend upon an intact morphogenesis checkpoint control to survive. These cells show defects in polarized growth despite the fact that the actin cytoskeleton appears normal. Our results suggest that Bed1 is a type II membrane protein localized in the endoplasmic reticulum. BED1 is significantly homologous to gma12+, a S. pombe gene coding for an alpha-1,2,-galactosyltransferase, suggesting that glycosylation of specific proteins or lipids could be important for signaling in the switch to polarized growth and in bud emergence.

scholarly journals The yeast ERAD-C ubiquitin ligase Doa10 recognizes an intramembrane degron

2015 ◽  
Vol 209 (2) ◽  
pp. 261-273 ◽  
Author(s):  
Gregor Habeck ◽  
Felix A. Ebner ◽  
Hiroko Shimada-Kreft ◽  
Stefan G. Kreft
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Ubiquitin Ligase ◽  
Protein Translocation ◽  
Dependent Manner ◽  
Β Subunit ◽  
Human Orthologue ◽  
Protein Ligases ◽  
Prevailing View

Aberrant endoplasmic reticulum (ER) proteins are eliminated by ER-associated degradation (ERAD). This process involves protein retrotranslocation into the cytosol, ubiquitylation, and proteasomal degradation. ERAD substrates are classified into three categories based on the location of their degradation signal/degron: ERAD-L (lumen), ERAD-M (membrane), and ERAD-C (cytosol) substrates. In Saccharomyces cerevisiae, the membrane proteins Hrd1 and Doa10 are the predominant ERAD ubiquitin-protein ligases (E3s). The current notion is that ERAD-L and ERAD-M substrates are exclusively handled by Hrd1, whereas ERAD-C substrates are recognized by Doa10. In this paper, we identify the transmembrane (TM) protein Sec61 β-subunit homologue 2 (Sbh2) as a Doa10 substrate. Sbh2 is part of the trimeric Ssh1 complex involved in protein translocation. Unassembled Sbh2 is rapidly degraded in a Doa10-dependent manner. Intriguingly, the degron maps to the Sbh2 TM region. Thus, in contrast to the prevailing view, Doa10 (and presumably its human orthologue) has the capacity for recognizing intramembrane degrons, expanding its spectrum of substrates.

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