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Hannah M Hankins, Yves Y Sere, Nicholas S Diab, Anant K Menon, Todd R Graham
Sorting of plasma membrane proteins into exocytic vesicles at the yeast trans-Golgi network (TGN) is believed to be mediated by their coalescence with specific lipids, but how these membrane-remodeling events are regulated is poorly understood. Here we show that the ATP-dependent phospholipid flippase Drs2 is required for efficient segregation of cargo into exocytic vesicles. The plasma membrane proteins Pma1 and Can1 are missorted from the TGN to the vacuole in drs2∆ cells. We also used a combination of flippase mutants that either gain or lose the ability to flip phosphatidylserine (PS) to determine that PS flip by Drs2 is its critical function in this sorting event...
December 15, 2015: Molecular Biology of the Cell
Carolina Hernández-Haro, Silvia Llopis, María Molina, Lucía Monteoliva, Concha Gil
UNLABELLED: Saccharomyces cerevisiae is considered a safe microorganism widely used as a dietary supplement. However, in the latest decades several cases of S. cerevisiae infections have been reported. Recent studies in a murine model of systemic infection have also revealed the virulence of some S. cerevisiae dietary strains. Here we use an immunoproteomic approach based on protein separation by 2D-PAGE followed by Western-blotting to compare the serological response against a virulent dietary and a non-virulent laboratory strains leading to the identification of highly different patterns of antigenic proteins...
January 1, 2015: Journal of Proteomics
Tomohiro Kinjo, Yuji Koseki, Maiko Kobayashi, Atsumi Yamada, Koji Morita, Kento Yamaguchi, Ryoya Tsurusawa, Gulcin Gulten, Hideyuki Komatsu, Hiroshi Sakamoto, James C Sacchettini, Mitsuru Kitamura, Shunsuke Aoki
To identify novel antibiotics against Mycobacterium tuberculosis, we performed a hierarchical structure-based drug screening (SBDS) targeting the enoyl-acyl carrier protein reductase (InhA) with a compound library of 154,118 chemicals. We then evaluated whether the candidate hit compounds exhibited inhibitory effects on the growth of two model mycobacterial strains: Mycobacterium smegmatis and Mycobacterium vanbaalenii. Two compounds (KE3 and KE4) showed potent inhibitory effects against both model mycobacterial strains...
May 24, 2013: Journal of Chemical Information and Modeling
Marissa A LeBlanc, Gregory D Fairn, Sarah B Russo, Ola Czyz, Vanina Zaremberg, L Ashley Cowart, Christopher R McMaster
The oxysterol binding protein family are amphitropic proteins that bind oxysterols, sterols, and possibly phosphoinositides, in a conserved binding pocket. The Saccharomyces cerevisiae oxysterol binding protein family member Kes1 (also known as Osh4) also binds phosphoinositides on a distinct surface of the protein from the conserved binding pocket. In this study, we determine that the oxysterol binding protein family member Kes1 is required to maintain the ratio of complex sphingolipids and levels of ceramide, sphingosine-phosphate and sphingosine...
2013: PloS One
Yoshiyuki Tsujimoto, Daisuke Takase, Hajime Okano, Naohiro Tomari, Kunihiko Watanabe, Hiroshi Matsui
We identified YPT31, which is involved in Golgi traffic, as a clotrimazole (CTZ)-resistance gene in a multicopy library screen. Multicopies of the YPT31 homolog YPT32 also conferred resistance to CTZ, and single disruption of YPT31 or YPT32 resulted in sensitivity to CTZ. Pdr5p, an ATP-binding cassette (ABC) transporter at the plasma membrane, was the most important factor for mediating basal resistance to CTZ, suggesting that Ypt31p and Ypt32p might be involved in the trafficking of Pdr5p to the plasma membrane...
January 2013: Journal of Bioscience and Bioengineering
Michelle L Villasmil, Vytas A Bankaitis, Carl J Mousley
The Kes1 OSBP (oxysterol-binding protein) is a key regulator of membrane trafficking through the TGN (trans-Golgi network) and endosomal membranes. We demonstrated recently that Kes1 acts as a sterol-regulated rheostat for TGN/endosomal phosphatidylinositol 4-phosphate signalling. Kes1 utilizes its dual lipid-binding activities to integrate endosomal lipid metabolism with TORC1 (target of rapamycin complex 1)-dependent proliferative pathways and transcriptional control of nutrient signalling.
April 2012: Biochemical Society Transactions
Carl J Mousley, Peihua Yuan, Naseem A Gaur, Kyle D Trettin, Aaron H Nile, Stephen J Deminoff, Brian J Dewar, Max Wolpert, Jeffrey M Macdonald, Paul K Herman, Alan G Hinnebusch, Vytas A Bankaitis
Kes1, and other oxysterol-binding protein superfamily members, are involved in membrane and lipid trafficking through trans-Golgi network (TGN) and endosomal systems. We demonstrate that Kes1 represents a sterol-regulated antagonist of TGN/endosomal phosphatidylinositol-4-phosphate signaling. This regulation modulates TOR activation by amino acids and dampens gene expression driven by Gcn4, the primary transcriptional activator of the general amino acid control regulon. Kes1-mediated repression of Gcn4 transcription factor activity is characterized by nonproductive Gcn4 binding to its target sequences, involves TGN/endosome-derived sphingolipid signaling, and requires activity of the cyclin-dependent kinase 8 (CDK8) module of the enigmatic "large Mediator" complex...
February 17, 2012: Cell
Gabriel Alfaro, Jesper Johansen, Shubha A Dighe, Giselle Duamel, Keith G Kozminski, Christopher T Beh
Oxysterol-binding protein (OSBP)-related protein Kes1/ Osh4p is implicated in nonvesicular sterol transfer between membranes in Saccharomyces cerevisiae. However, we found that Osh4p associated with exocytic vesicles that move from the mother cell into the bud, where Osh4p facilitated vesicle docking by the exocyst tethering complex at sites of polarized growth on the plasma membrane. Osh4p formed complexes with the small GTPases Cdc42p, Rho1p and Sec4p, and the exocyst complex subunit Sec6p, which was also required for Osh4p association with vesicles...
November 2011: Traffic
Marissa A LeBlanc, Christopher R McMaster
The Saccharomyces cerevisiae protein Kes1/Osh4 is a member of the enigmatic family of oxysterol-binding proteins found throughout Eukarya united by a β-barrel structure that binds sterols and oxysterols. In this study, we determined that phosphoinositides are the major determinant in membranes that facilitate Kes1 association both in vitro and in cells. Increased expression of Kes1 in yeast cells decreased the levels of both phosphatidylinositol 4-phosphate (PI4P) and phosphatidylinositol 3-phosphate (PI3P)...
October 29, 2010: Journal of Biological Chemistry
Marissa A LeBlanc, Christopher R McMaster
Saccharomyces cerevisiae remains an ideal organism for studying the cell biological roles of lipids in vivo, as yeast has phospholipid metabolic pathways similar to mammalian cells, is easy and economical to manipulate, and is genetically tractable. The availability of isogenic strains containing specific genetic inactivation of each non-essential gene allowed for the development of a high-throughput method, called synthetic genetic analysis (SGA), to identify and describe precise pathways or functions associated with specific genes...
August 2010: Biochemistry and Cell Biology, Biochimie et Biologie Cellulaire
Baby-Periyanayaki Muthusamy, Sumana Raychaudhuri, Paramasivam Natarajan, Fumiyoshi Abe, Ke Liu, William A Prinz, Todd R Graham
The oxysterol binding protein homologue Kes1p has been implicated in nonvesicular sterol transport in Saccharomyces cerevisiae. Kes1p also represses formation of protein transport vesicles from the trans-Golgi network (TGN) through an unknown mechanism. Here, we show that potential phospholipid translocases in the Drs2/Dnf family (type IV P-type ATPases [P4-ATPases]) are downstream targets of Kes1p repression. Disruption of KES1 suppresses the cold-sensitive (cs) growth defect of drs2Delta, which correlates with an enhanced ability of Dnf P4-ATPases to functionally substitute for Drs2p...
June 2009: Molecular Biology of the Cell
Gabriel Schaaf, Eric A Ortlund, Kimberly R Tyeryar, Carl J Mousley, Kristina E Ile, Teresa A Garrett, Jihui Ren, Melissa J Woolls, Christian R H Raetz, Matthew R Redinbo, Vytas A Bankaitis
Sec14, the major yeast phosphatidylinositol (PtdIns)/phosphatidylcholine (PtdCho) transfer protein, regulates essential interfaces between lipid metabolism and membrane trafficking from the trans-Golgi network (TGN). How Sec14 does so remains unclear. We report that Sec14 binds PtdIns and PtdCho at distinct (but overlapping) sites, and both PtdIns- and PtdCho-binding activities are essential Sec14 activities. We further show both activities must reside within the same molecule to reconstitute a functional Sec14 and for effective Sec14-mediated regulation of phosphoinositide homeostasis in vivo...
February 1, 2008: Molecular Cell
G D Fairn, C R McMaster
OSBP (oxysterol-binding protein) and ORPs (OSBP-related proteins) constitute an enigmatic eukaryotic protein family that is united by a signature domain that binds oxysterols, sterols, and possibly other hydrophobic ligands. The human genome contains 12 OSBP/ORP family members genes, while that of the budding yeast Saccharomyces cerevisiae encodes seven OSBP homologues (Osh). Of these, Osh4 (also referred to as Kes1) has been the most widely studied to date. Recently, three-dimensional crystal structures of Osh4 with and without sterols bound within the core of the protein were determined...
January 2008: Cellular and Molecular Life Sciences: CMLS
Gregory D Fairn, Amy J Curwin, Christopher J Stefan, Christopher R McMaster
The Saccharomyces cerevisiae phosphatidylcholine/phosphatidylinositol transfer protein Sec14p is required for Golgi apparatus-derived vesicular transport through coordinate regulation of phospholipid metabolism. Sec14p is normally essential. The essential requirement for SEC14 can be bypassed by inactivation of (i) the CDP-choline pathway for phosphatidylcholine synthesis or (ii) KES1, which encodes an oxysterol binding protein. A unique screen was used to determine genome-wide genetic interactions for the essential gene SEC14 and to assess whether the two modes of "sec14 bypass" were similar or distinct...
September 25, 2007: Proceedings of the National Academy of Sciences of the United States of America
Keith G Kozminski, Gabriel Alfaro, Shubha Dighe, Christopher T Beh
Polarized cell growth requires the establishment of an axis of growth along which secretion can be targeted to a specific site on the cell cortex. How polarity establishment and secretion are choreographed is not fully understood, though Rho GTPase- and Rab GTPase-mediated signaling is required. Superimposed on this regulation are the functions of specific lipids and their cognate binding proteins. In a screen for Saccharomyces cerevisiae genes that interact with Rho family CDC42 to promote polarity establishment, we identified KES1/OSH4, which encodes a homologue of mammalian oxysterol-binding protein (OSBP)...
September 2006: Traffic
Takamitsu Sano, Akio Kihara, Fumiko Kurotsu, Soichiro Iwaki, Yasuyuki Igarashi
Sphingoid long-chain base 1-phosphates (LCBPs) are widely conserved, bioactive lipid molecules. In yeast, LCBPs are known to be involved in several cellular responses such as heat shock resistance and Ca(2+) mobilization, although their target molecules and signaling pathways remain unclear. To identify genes involved in LCBP signaling and in regulation of LCBP synthesis, we performed transposon mutagenesis in cells lacking the LCBP lyase DPL1 and LCBP phosphatase LCB3 genes and screened for phytosphingosine-resistant clones...
November 4, 2005: Journal of Biological Chemistry
Young Jun Im, Sumana Raychaudhuri, William A Prinz, James H Hurley
The oxysterol-binding-protein (OSBP)-related proteins (ORPs) are conserved from yeast to humans, and are implicated in the regulation of sterol homeostasis and in signal transduction pathways. Here we report the structure of the full-length yeast ORP Osh4 (also known as Kes1) at 1.5-1.9 A resolution in complexes with ergosterol, cholesterol, and 7-, 20- and 25-hydroxycholesterol. We find that a single sterol molecule binds within a hydrophobic tunnel in a manner consistent with a transport function for ORPs...
September 1, 2005: Nature
Alison Coluccio, Maria Malzone, Aaron M Neiman
SEC9 and SPO20 encode SNARE proteins related to the mammalian SNAP-25 family. Sec9p associates with the SNAREs Sso1/2p and Snc1/2p to promote the fusion of vesicles with the plasma membrane. Spo20p functions with the same two partner SNAREs to mediate the fusion of vesicles with the prospore membrane during sporogenesis. A chimeric molecule, in which the helices of Sec9p that bind to Sso1/2p and Snc1/2p are replaced with the homologous regions of Spo20p, will not support vesicle fusion in vegetative cells. The phosphatidylinositol-4-phosphate-5-kinase MSS4 was isolated as a high-copy suppressor that permits this chimera to rescue the temperature-sensitive growth of a sec9-4 mutant...
January 2004: Genetics
Y Xu, Y Liu, N D Ridgway, C R McMaster
Oxysterol-binding proteins (OSBPs) are a family of eukaryotic intracellular lipid receptors. Mammalian OSBP1 binds oxygenated derivatives of cholesterol and mediates sterol and phospholipid synthesis through as yet poorly undefined mechanisms. The precise cellular roles for the remaining members of the oxysterol-binding protein family remain to be elucidated. In yeast, a family of OSBPs has been identified based on primary sequence similarity to the ligand binding domain of mammalian OSBP1. Yeast Kes1p, an oxysterol-binding protein family member that consists of only the ligand binding domain, has been demonstrated to regulate the Sec14p pathway for Golgi-derived vesicle transport...
May 25, 2001: Journal of Biological Chemistry
B Purnelle, F Coster, A Goffeau
We have sequenced and analysed a 55786 bp fragment located on the left arm of chromosome XVI of Saccharomyces cerevisiae. The sequence contains 29 non-overlapping open reading frames (ORFs) longer than 300 bp, among which 12 genes have previously been sequenced: OYE3, REV3, SVS1, BEM4, CDC60, KIP2, PEP4, SPK1, PAL1, KES1, SNR17B and RPL37A. Three new ORFs, P2591, P2594 and P2597 are highly homologous to the human phosphotyrosyl phosphatase activator PTPA, to the pleiotropic regulator PRL1 of PP1 and PP2a protein phosphatases in plants and to the protein kinase PAR-1 in Caenorhabditis elegans, respectively...
November 1996: Yeast
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