scholarly journals Lipid-regulated sterol transfer between closely apposed membranes by oxysterol-binding protein homologues

2009 ◽  
Vol 187 (6) ◽  
pp. 889-903 ◽  
Author(s):  
Timothy A. Schulz ◽  
Mal-Gi Choi ◽  
Sumana Raychaudhuri ◽  
Jason A. Mears ◽  
Rodolfo Ghirlando ◽  
...  
Keyword(s):  
Binding Protein ◽  
Binding Pocket ◽  
Lipid Binding ◽  
Dependent Manner ◽  
Oxysterol Binding Protein ◽  
The Core ◽  
Contact Sites ◽  
Core Lipid ◽  
Related Proteins ◽  
Distal Site

Sterols are transferred between cellular membranes by vesicular and poorly understood nonvesicular pathways. Oxysterol-binding protein–related proteins (ORPs) have been implicated in sterol sensing and nonvesicular transport. In this study, we show that yeast ORPs use a novel mechanism that allows regulated sterol transfer between closely apposed membranes, such as organelle contact sites. We find that the core lipid-binding domain found in all ORPs can simultaneously bind two membranes. Using Osh4p/Kes1p as a representative ORP, we show that ORPs have at least two membrane-binding surfaces; one near the mouth of the sterol-binding pocket and a distal site that can bind a second membrane. The distal site is required for the protein to function in cells and, remarkably, regulates the rate at which Osh4p extracts and delivers sterols in a phosphoinositide-dependent manner. Together, these findings suggest a new model of how ORPs could sense and regulate the lipid composition of adjacent membranes.

scholarly journals A role for oxysterol-binding protein–related protein 5 in endosomal cholesterol trafficking

2011 ◽  
Vol 192 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Ximing Du ◽  
Jaspal Kumar ◽  
Charles Ferguson ◽  
Timothy A. Schulz ◽  
Yan Shan Ong ◽  
...  
Keyword(s):  
Binding Protein ◽  
Lipid Binding ◽  
Cholesterol Trafficking ◽  
Cholesterol Accumulation ◽  
Oxysterol Binding Protein ◽  
Late Endosomes ◽  
Evolutionarily Conserved ◽  
Niemann Pick ◽  
Related Proteins ◽  
Lipid Binding Proteins

Oxysterol-binding protein (OSBP) and its related proteins (ORPs) constitute a large and evolutionarily conserved family of lipid-binding proteins that target organelle membranes to mediate sterol signaling and/or transport. Here we characterize ORP5, a tail-anchored ORP protein that localizes to the endoplasmic reticulum. Knocking down ORP5 causes cholesterol accumulation in late endosomes and lysosomes, which is reminiscent of the cholesterol trafficking defect in Niemann Pick C (NPC) fibroblasts. Cholesterol appears to accumulate in the limiting membranes of endosomal compartments in ORP5-depleted cells, whereas depletion of NPC1 or both ORP5 and NPC1 results in luminal accumulation of cholesterol. Moreover, trans-Golgi resident proteins mislocalize to endosomal compartments upon ORP5 depletion, which depends on a functional NPC1. Our results establish the first link between NPC1 and a cytoplasmic sterol carrier, and suggest that ORP5 may cooperate with NPC1 to mediate the exit of cholesterol from endosomes/lysosomes.

PI4P/PS countertransport by ORP10 at ER–endosome membrane contact sites regulates endosome fission

2021 ◽  
Vol 221 (1) ◽  
Author(s):  
Asami Kawasaki ◽  
Akiko Sakai ◽  
Hiroki Nakanishi ◽  
Junya Hasegawa ◽  
Tomohiko Taguchi ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Binding Protein ◽  
Dependent Manner ◽  
Oxysterol Binding Protein ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Lipid Exchange ◽  
Membrane Contact ◽  
Phosphatidylinositol 4

Membrane contact sites (MCSs) serve as a zone for nonvesicular lipid transport by oxysterol-binding protein (OSBP)-related proteins (ORPs). ORPs mediate lipid countertransport, in which two distinct lipids are transported counterdirectionally. How such lipid countertransport controls specific biological functions, however, remains elusive. We report that lipid countertransport by ORP10 at ER–endosome MCSs regulates retrograde membrane trafficking. ORP10, together with ORP9 and VAP, formed ER–endosome MCSs in a phosphatidylinositol 4-phosphate (PI4P)-dependent manner. ORP10 exhibited a lipid exchange activity toward its ligands, PI4P and phosphatidylserine (PS), between liposomes in vitro, and between the ER and endosomes in situ. Cell biological analysis demonstrated that ORP10 supplies a pool of PS from the ER, in exchange for PI4P, to endosomes where the PS-binding protein EHD1 is recruited to facilitate endosome fission. Our study highlights a novel lipid exchange at ER–endosome MCSs as a nonenzymatic PI4P-to-PS conversion mechanism that organizes membrane remodeling during retrograde membrane trafficking.

scholarly journals Nonvesicular sterol movement from plasma membrane to ER requires oxysterol-binding protein–related proteins and phosphoinositides

2006 ◽  
Vol 173 (1) ◽  
pp. 107-119 ◽  
Author(s):  
Sumana Raychaudhuri ◽  
Young Jun Im ◽  
James H. Hurley ◽  
William A. Prinz
Keyword(s):  
Plasma Membrane ◽  
Binding Protein ◽  
Large Family ◽  
Lipid Binding ◽  
Oxysterol Binding Protein ◽  
Sterol Transport ◽  
Cellular Compartments ◽  
Related Proteins ◽  
Lipid Binding Proteins

Sterols are moved between cellular membranes by nonvesicular pathways whose functions are poorly understood. In yeast, one such pathway transfers sterols from the plasma membrane (PM) to the endoplasmic reticulum (ER). We show that this transport requires oxysterol-binding protein (OSBP)–related proteins (ORPs), which are a large family of conserved lipid-binding proteins. We demonstrate that a representative member of this family, Osh4p/Kes1p, specifically facilitates the nonvesicular transfer of cholesterol and ergosterol between membranes in vitro. In addition, Osh4p transfers sterols more rapidly between membranes containing phosphoinositides (PIPs), suggesting that PIPs regulate sterol transport by ORPs. We confirmed this by showing that PM to ER sterol transport slows dramatically in mutants with conditional defects in PIP biosynthesis. Our findings argue that ORPs move sterols among cellular compartments and that sterol transport and intracellular distribution are regulated by PIPs.

scholarly journals Identification and evaluation of metastasis-related proteins, oxysterol binding protein-like 5 and calumenin, in lung tumors

2015 ◽  
Vol 47 (1) ◽  
pp. 195-205 ◽  
Author(s):  
KAZUYA NAGANO ◽  
SUNAO IMAI ◽  
XILULI ZHAO ◽  
TAKUYA YAMASHITA ◽  
YASUO YOSHIOKA ◽  
...  
Keyword(s):  
Binding Protein ◽  
Lung Tumors ◽  
Oxysterol Binding Protein ◽  
Related Proteins

scholarly journals The oxysterol-binding protein superfamily: new concepts and old proteins

2012 ◽  
Vol 40 (2) ◽  
pp. 469-473 ◽  
Author(s):  
Michelle L. Villasmil ◽  
Vytas A. Bankaitis ◽  
Carl J. Mousley
Keyword(s):  
Lipid Metabolism ◽  
Membrane Trafficking ◽  
Transcriptional Control ◽  
Binding Protein ◽  
Lipid Binding ◽  
Oxysterol Binding Protein ◽  
New Concepts ◽  
Endosomal Membranes ◽  
Phosphatidylinositol 4 ◽  
Golgi Network

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.

The roles of the human lipid-binding proteins ORP9S and ORP10S in vesicular transport

2005 ◽  
Vol 83 (5) ◽  
pp. 631-636 ◽  
Author(s):  
Gregory D Fairn ◽  
Christopher R McMaster
Keyword(s):  
Binding Protein ◽  
Vesicular Transport ◽  
Lipid Binding ◽  
Yeast Cells ◽  
Phospholipid Transfer Protein ◽  
Related Protein ◽  
Oxysterol Binding Protein ◽  
Transfer Protein ◽  
Phospholipid Transfer ◽  
Lipid Binding Proteins

Inactivation of the yeast oxysterol binding protein related protein (ORP) family member Kes1p allows yeast cells to survive in the absence of Sec14p, a phospholipid transfer protein required for cell viability because of the role it plays in transporting vesicles from the Golgi. We expressed human ORP9S and ORP10S in yeast lacking Sec14p and Kes1p function, and found that ORP9S completely complemented Kes1p function, whereas ORP10S possessed only a weak ability to replace Kes1p function. Purified ORP9S protein bound several phosphoinositides, whereas ORP10 bound specifically to phosphatidylinositol 3-phosphate. The combined evidence demonstrates that only a subset of human ORP proteins can function as negative regulators of Golgi-derived vesicular transport.Key words: phospholipid, Saccharomyces cerevisiae, Golgi, vesicular transport, oxysterol binding protein related protein.

Fungal oxysterol-binding protein-related proteins promote pathogen virulence and activate plant immunity

2021 ◽  
Author(s):  
Meng-Meng Chen ◽  
Si-Ru Yang ◽  
Jian Wang ◽  
Ya-Li Fang ◽  
You-Liang Peng ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Oxidative Burst ◽  
Plant Disease Resistance ◽  
Binding Protein ◽  
Plant Innate Immunity ◽  
Suspension Cells ◽  
Callose Deposition ◽  
Fungal Virulence ◽  
Oxysterol Binding Protein ◽  
Related Proteins

Abstract Oxysterol-binding protein-related proteins (ORPs) are a conserved class of lipid transfer proteins that are closely involved in multiple cellular processes in eukaryotes but their roles in plant-pathogen interactions are mostly unknown. We showed that transient expression of ORPs of Magnaporthe oryzae (MoORPs) in Nicotiana benthamina plants triggered oxidative burst and cell death; treatment of tobacco Bright Yellow-2 suspension cells with recombinant MoORPs elicited the production of reactive oxygen species. Despite that ORPs are normally described as intracellular proteins, we detected MoORPs in fungal cultural filtrates and intercellular fluids from barley plants infected with the fungus. More importantly, infiltration of Arabidopsis plants with recombinant Arabidopsis or fungal ORPs activated oxidative burst, callose deposition, PR1 gene expression, and enhanced plant disease resistance, implying that ORPs may function as endogenous and exogenous danger signals triggering plant innate immunity. Extracellular application of fungal ORPs exerted an opposite impact on salicylic acid and jasmonic acid/ethylene signaling pathways. The Brassinosteroid Insensitive 1-associated Kinase 1 was dispensable for the ORP-activated defense. Besides, simultaneous knockout of MoORP1 and MoORP3 abolished fungal colony radial growth and conidiation, whereas double knockout of MoORP1 and MoORP2 compromised fungal virulence on barley and rice plants. These observations collectively highlight the multifaceted role of MoORPs in the modulation of plant innate immunity and promotion of fungal development and virulence in M. oryzae.

scholarly journals OSBP-Related Protein Family in Lipid Transport over Membrane Contact Sites

2015 ◽  
Vol 8s1 ◽  
pp. LPI.S31726 ◽  
Author(s):  
Vesa M. Olkkonen
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Binding Protein ◽  
High Capacity ◽  
Retrograde Transport ◽  
Protein Family ◽  
Oxysterol Binding Protein ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Membrane Contact

Increasing evidence suggests that oxysterol-binding protein-related proteins (ORPs) localize at membrane contact sites, which are high-capacity platforms for inter-organelle exchange of small molecules and information. ORPs can simultaneously associate with the two apposed membranes and transfer lipids across the interbilayer gap. Oxysterol-binding protein moves cholesterol from the endoplasmic reticulum to trans-Golgi, driven by the retrograde transport of phosphatidylinositol-4-phosphate (PI4P). Analogously, yeast Osh6p mediates the transport of phosphatidylserine from the endoplasmic reticulum to the plasma membrane in exchange for PI4P, and ORP5 and -8 are suggested to execute similar functions in mammalian cells. ORPs may share the capacity to bind PI4P within their ligand-binding domain, prompting the hypothesis that bidirectional transport of a phosphoinositide and another lipid may be a common theme among the protein family. This model, however, needs more experimental support and does not exclude a function of ORPs in lipid signaling.

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