scholarly journals The cell polarity proteins Boi1p and Boi2p stimulate vesicle fusion at the plasma membrane of yeast cells

2017 ◽  
Vol 130 (18) ◽  
pp. 2996-3008 ◽  
Author(s):  
Jochen Kustermann ◽  
Yehui Wu ◽  
Lucia Rieger ◽  
Dirk Dedden ◽  
Tamara Phan ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Polarity ◽  
Vesicle Fusion ◽  
Yeast Cells ◽  
Polarity Proteins

scholarly journals Electrostatic plasma membrane targeting contributes to Dlg function in cell polarity and tumorigenesis

Development ◽  
2021 ◽  
pp. dev.196956
Author(s):  
Juan Lu ◽  
Wei Dong ◽  
Yan Tao ◽  
Yang Hong
Keyword(s):  
Plasma Membrane ◽  
Tumor Suppressor ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Significant Role ◽  
Discs Large ◽  
Cortical Localization ◽  
Polarity Proteins ◽  
Positively Charged

Discs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but is also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in polarity and tumorigenesis, but the exact mechanisms targeting Dlg to PM remain to be fully elucidated. Here we show that, similar to the recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2. Electrostatic targeting by the polybasic domain contributes significantly to the PM localization of Dlg in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by the interactions between Dlg and another basolateral polarity protein and tumor suppressor Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.

scholarly journals The cell polarity proteins Boi1p and Boi2p stimulate vesicle fusion at the plasma membrane of yeast cells

2017 ◽  
Author(s):  
Jochen Kustermann ◽  
Yehui Wu ◽  
Lucia Rieger ◽  
Dirk Dedden ◽  
Tamara Phan ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Vesicle Fusion ◽  
Snare Complex ◽  
Yeast Cells ◽  
Protein Interaction Data ◽  
Polar Growth ◽  
Interaction Data ◽  
Summary Statement ◽  
Snare Complex Formation ◽  
Novel Protein

AbstractEukaryotic cells can direct secretion to defined regions of their plasma membrane. These regions are distinguished by an elaborate architecture of proteins and lipids that are specialized to capture and fuse post-Golgi vesicles. Here we show that the proteins Boi1p and Boi2p are important elements of this area of active exocytosis at the tip of growing yeast cells. Cells lacking Boi1p and Boi2p accumulate secretory vesicles in their bud. The essential PH domains of Boi1p and Boi2p interact with Sec1p, a protein required for SNARE complex formation and vesicle fusion. Sec1p loses its tip localization in cells depleted of Boi1p and Boi2p but can partially compensate for their loss upon overexpression. The capacity to simultaneously bind phospholipids, Sec1p, multiple subunits of the exocyst, Cdc42p, and the module for generating active Cdc42p identify Boi1p and Boi2p as essential mediators between exocytosis and polar growth.Summary statementA novel protein complex connects vesicle fusion with Cdc42p activation. Genetic and protein interaction data suggest that its central members Boi1p and Boi2p chaperone the formation of the docking complex.

scholarly journals Electrostatic Plasma Membrane Targeting is Essential for Dlg Function in Cell Polarity and Tumorigenesis

2020 ◽  
Author(s):  
Juan Lu ◽  
Wei Dong ◽  
Yan Tao ◽  
Yang Hong
Keyword(s):  
Plasma Membrane ◽  
Tumor Suppressor ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Primary Mechanism ◽  
Discs Large ◽  
Cortical Localization ◽  
Polarity Proteins ◽  
Positively Charged

SUMMARYDiscs large (Dlg) is an essential polarity protein and a tumor suppressor originally characterized in Drosophila but is also well conserved in vertebrates. Like the majority of polarity proteins, plasma membrane (PM)/cortical localization of Dlg is required for its function in regulating apical-basal polarity and tumorigenesis, but the exact mechanisms targeting Dlg to PM remain to be unclear. Here we show that, similar to recently discovered polybasic polarity proteins such as Lgl and aPKC, Dlg also contains a positively charged polybasic domain that electrostatically binds the PM phosphoinositides PI4P and PI(4,5)P2. Electrostatic targeting by the polybasic domain acts as the primary mechanism localizing Dlg to the PM in follicular and early embryonic epithelial cells, and is crucial for Dlg to regulate both polarity and tumorigenesis. The electrostatic PM targeting of Dlg is controlled by a potential phosphorylation-dependent allosteric regulation of its polybasic domain, and is specifically enhanced by interactions between Dlg and another basolateral polarity protein and tumor suppressor Scrib. Our studies highlight an increasingly significant role of electrostatic PM targeting of polarity proteins in regulating cell polarity.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Deformation of Yeast Plasma Membrane by Ethidium Bromide

1988 ◽  
Vol 46 ◽  
pp. 254-255
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Thin Section ◽  
Ethidium Bromide ◽  
Freeze Fracture ◽  
Mutagenic Effect ◽  
Yeast Cells ◽  
Hydrophobic Region ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Deep Pits

The mutagenic effect of ethidium bromide on the mitochondrial DNA is well established. Using thin section electron microscopy, it was shown that when yeast cells were grown in the presence of ethidium bromide, besides alterations in the mitochondria, the plasma membrane also showed alterations consisting of 75 to 110 nm-deep pits. Furthermore, ethidium bromide induced an increase in the length and number of endoplasmic reticulum and in the number of intracytoplasmic vesicles.Freeze-fracture, by splitting the hydrophobic region of the membrane, allows the visualization of the surface view of the membrane, and consequently, any alteration induced by ethidium bromide on the membrane can be better examined by this method than by the thin section method.Yeast cells, Candida utilis. were grown in the presence of 35 μM ethidium bromide. Cells were harvested and freeze-fractured according to the procedure previously described.

scholarly journals Septin-dependent compartmentalization of the endoplasmic reticulum during yeast polarized growth

2005 ◽  
Vol 169 (6) ◽  
pp. 897-908 ◽  
Author(s):  
Cosima Luedeke ◽  
Stéphanie Buvelot Frei ◽  
Ivo Sbalzarini ◽  
Heinz Schwarz ◽  
Anne Spang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Diffusion Barriers ◽  
Yeast Cells ◽  
Dependent Manner ◽  
Protein Diffusion ◽  
Ultrastructural Studies ◽  
Bud Neck ◽  
Er Membrane

Polarized cells frequently use diffusion barriers to separate plasma membrane domains. It is unknown whether diffusion barriers also compartmentalize intracellular organelles. We used photobleaching techniques to characterize protein diffusion in the yeast endoplasmic reticulum (ER). Although a soluble protein diffused rapidly throughout the ER lumen, diffusion of ER membrane proteins was restricted at the bud neck. Ultrastructural studies and fluorescence microscopy revealed the presence of a ring of smooth ER at the bud neck. This ER domain and the restriction of diffusion for ER membrane proteins through the bud neck depended on septin function. The membrane-associated protein Bud6 localized to the bud neck in a septin-dependent manner and was required to restrict the diffusion of ER membrane proteins. Our results indicate that Bud6 acts downstream of septins to assemble a fence in the ER membrane at the bud neck. Thus, in polarized yeast cells, diffusion barriers compartmentalize the ER and the plasma membrane along parallel lines.

Identification of ferrichrome- and ferrioxamine B-mediated iron uptake by Aspergillus fumigatus

2016 ◽  
Vol 473 (9) ◽  
pp. 1203-1213 ◽  
Author(s):  
Yong-Sung Park ◽  
Ju-Yeon Kim ◽  
Cheol-Won Yun
Keyword(s):  
Gene Expression ◽  
Plasma Membrane ◽  
Aspergillus Fumigatus ◽  
Virulence Factors ◽  
Membrane Transporters ◽  
Yeast Cells ◽  
Double Deletion ◽  
Ferrioxamine B ◽  
Uptake Activity ◽  
Opportunistic Fungal Pathogen

Aspergillus fumigatus is an opportunistic fungal pathogen for immunocompromised patients, and genes involved in siderophore metabolism have been identified as virulence factors. Recently, we identified the membrane transporters sit1 and sit2, which are putative virulence factors of A. fumigatus; sit1 and sit2 are homologous to yeast Sit1, and sit1 and sit2 gene expression was up-regulated after iron depletion. When expressed heterologously in Saccharomyces cerevisiae, sit1 and sit2 were localized to the plasma membrane; sit1 efficiently complemented ferrichrome (FC) and ferrioxamine B (FOB) uptake in yeast cells, whereas sit2 complemented only FC uptake. Deletion of sit1 resulted in a decrease in FOB and FC uptake, and deletion of sit2 resulted in a decrease in FC uptake in A. fumigatus. It is of interest that a sit1 and sit2 double-deletion mutant resulted in a synergistic decrease in FC uptake activity. Both sit1 and sit2 were localized to the plasma membrane in A. fumigatus. The expression levels of the sit1 and sit2 genes were dependent on hapX under low-but not high-iron conditions. Furthermore, mirB, and sidA gene expression was up-regulated and sreA expression down-regulated when sit1 and sit2 were deleted. Although sit1 and sit2 failed to affect mouse survival rate, these genes affected conidial killing activity. Taken together, our results suggest that sit1 and sit2 are siderophore transporters and putative virulence factors localized to the plasma membrane.

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