scholarly journals Non-Canonical Regulation of Phosphatidylserine Metabolism by a Phosphatidylinositol Transfer Protein and a Phosphatidylinositol 4-OH Kinase

2019 ◽  
Author(s):  
Yaxi Wang ◽  
Peihua Yuan ◽  
Ashutosh Tripathi ◽  
Martin Rodriguez ◽  
Max Lönnfors ◽  
...  
Keyword(s):  
Functional Data ◽  
Physical Interaction ◽  
Uncharacterized Protein ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Membrane Contact ◽  
Phosphatidylinositol Transfer ◽  
Independent Association ◽  
Phosphatidylinositol 4 ◽  
Canonical Activity

ABSTRACTThe phosphatidylserine (PtdSer) decarboxylase Psd2 is proposed to engage in an endoplasmic reticulum (ER)-Golgi/endosome membrane contact site (MCS) that facilitates phosphatidylserine decarboxylation to phosphatidylethanomaine (PtdEtn) in Saccharomyces cerevisiae. While this MCS is envisioned to consist of Psd2, the Sec14-like phosphatidylinositol transfer protein (PITP) Sfh4, the Stt4 phosphatidylinositol (PtdIns) 4-OH kinase, the Scs2 tether, and at least one other uncharacterized protein, functional data that address key foundations of this model are sparse. We now report that Psd2, Sfh4 and Stt4 are the only components individually required for biologically sufficient Psd2-dependent PtdEtn production. Surprisingly, neither the PtdIns-transfer activity of Sfh4 nor its capacity to activate Stt4 is required to stimulate the Psd2 pathway. Instead, Sfh4 activates the Psd2 pathway via a specific Sfh4-Psd2 physical interaction. Whereas the data indicate an Sfh4-independent association of Stt4 with Psd2 as well, we find Stt4 also regulates Psd2 activity indirectly by influencing the PtdSer pool accessible to Psd2 for decarboxylation. These collective results demonstrate that the proposed ER-Golgi/endosomal MCS model fails to provide an accurate description of the Psd2 system in yeast, and provide an example where the biological function of a Sec14-like PITP is uncoupled from its ‘canonical’ activity as a PtdIns transfer protein.

scholarly journals Noncanonical regulation of phosphatidylserine metabolism by a Sec14-like protein and a lipid kinase

2020 ◽  
Vol 219 (5) ◽  
Author(s):  
Yaxi Wang ◽  
Peihua Yuan ◽  
Aby Grabon ◽  
Ashutosh Tripathi ◽  
Dongju Lee ◽  
...  
Keyword(s):  
Lipid Transfer Protein ◽  
Physical Interaction ◽  
Lipid Transfer ◽  
Uncharacterized Protein ◽  
Lipid Kinase ◽  
Transfer Protein ◽  
Transfer Activity ◽  
Phosphatidylinositol Transfer

The yeast phosphatidylserine (PtdSer) decarboxylase Psd2 is proposed to engage in a membrane contact site (MCS) for PtdSer decarboxylation to phosphatidylethanolamine (PtdEtn). This proposed MCS harbors Psd2, the Sec14-like phosphatidylinositol transfer protein (PITP) Sfh4, the Stt4 phosphatidylinositol (PtdIns) 4-OH kinase, the Scs2 tether, and an uncharacterized protein. We report that, of these components, only Sfh4 and Stt4 regulate Psd2 activity in vivo. They do so via distinct mechanisms. Sfh4 operates via a mechanism for which its PtdIns-transfer activity is dispensable but requires an Sfh4-Psd2 physical interaction. The other requires Stt4-mediated production of PtdIns-4-phosphate (PtdIns4P), where Stt4 (along with the Sac1 PtdIns4P phosphatase and endoplasmic reticulum–plasma membrane tethers) indirectly modulate Psd2 activity via a PtdIns4P homeostatic mechanism that influences PtdSer accessibility to Psd2. These results identify an example in which the biological function of a Sec14-like PITP is cleanly uncoupled from its canonical in vitro PtdIns-transfer activity and challenge popular functional assumptions regarding lipid-transfer protein involvements in MCS function.

scholarly journals Novel Regulation of Lipid Metabolism by a Phosphatidylinositol Transfer Protein and a Phosphatidylinositol 4‐Kinase

2019 ◽  
Vol 33 (S1) ◽  
Author(s):  
Yaxi Wang ◽  
Peihua Yuan ◽  
Martin Rodriguez ◽  
Ashutosh Tripathi ◽  
Max Lönnfors ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer ◽  
Phosphatidylinositol 4

An essential role for phosphatidylinositol transfer protein in phospholipase C-Mediated inositol lipid signaling

Cell ◽  
1993 ◽  
Vol 74 (5) ◽  
pp. 919-928 ◽  
Author(s):  
Geraint M.H. Thomas ◽  
Emer Cunningham ◽  
Amanda Fensome ◽  
Andrew Ball ◽  
Nicholas F. Totty ◽  
...  
Keyword(s):  
Phospholipase C ◽  
Essential Role ◽  
Lipid Signaling ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer

scholarly journals Phosphatidylinositol Transfer Protein Expression Altered by Aging and Parkinson Disease

2006 ◽  
Vol 26 (7-8) ◽  
pp. 1151-1164 ◽  
Author(s):  
Małgorzata Chalimoniuk ◽  
Gerry T. Snoek ◽  
Agata Adamczyk ◽  
Andrzej Małecki ◽  
Joanna B. Strosznajder
Keyword(s):  
Protein Expression ◽  
Parkinson Disease ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer

scholarly journals Resynthesis of phosphatidylinositol in permeabilized neutrophils following phospholipase Cβ activation: transport of the intermediate, phosphatidic acid, from the plasma membrane to the endoplasmic reticulum for phosphatidylinositol resynthesis is not dependent on soluble lipid carriers or vesicular transport

1999 ◽  
Vol 341 (2) ◽  
pp. 435-444 ◽  
Author(s):  
Jacqueline WHATMORE ◽  
Claudia WIEDEMANN ◽  
Pennti SOMERHARJU ◽  
Philip SWIGART ◽  
Shamshad COCKCROFT
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Vesicular Transport ◽  
Human Neutrophils ◽  
Permeabilized Cells ◽  
Transfer Protein ◽  
Membrane Contact ◽  
Phosphatidylinositol Transfer ◽  
Pi Hydrolysis ◽  
Hydrolysis Of

Receptor-mediated phospholipase C (PLC) hydrolysis of phosphoinositides is accompanied by the resynthesis of phosphatidylinositol (PI). Hydrolysis of phosphoinositides occurs at the plasma membrane, and the resulting diacylglycerol (DG) is converted into phosphatidate (PA). Two enzymes located at the endoplasmic reticulum (ER) function sequentially to convert PA back into PI. We have established an assay whereby the resynthesis of PI could be followed in permeabilized cells. In the presence of [γ-32P]ATP, DG generated by PLC activation accumulates label when converted into PA. The 32P-labelled PA is subsequently converted into labelled PI. The formation of labelled PI reports the arrival of labelled PA from the plasma membrane to the ER. Cytosol-depleted, permeabilized human neutrophils are capable of PI resynthesis following stimulation of PLCβ (in the presence of phosphatidylinositol-transfer protein), provided that CTP and inositol are also present. We also found that wortmannin, an inhibitor of endocytosis, or cooling the cells to 15 °C did not stop PI resynthesis. We conclude that PI resynthesis is dependent neither on vesicular transport mechanisms nor on freely diffusible, soluble transport proteins. Phosphatidylcholine-derived PA generated by the ADP-ribosylation-factor-stimulated phospholipase D pathway was found to accumulate label, reflecting the rapid cycling of PA to DG, and back. This labelled PA was not converted into PI. We conclude that PA derived from the PLC pathway is selected for PI resynthesis, and its transfer to the ER could be membrane-protein-mediated at sites of close membrane contact.

Both isoforms of mammalian phosphatidylinositol transfer protein are capable of binding and transporting sphingomyelin

2002 ◽  
Vol 1580 (1) ◽  
pp. 67-76 ◽  
Author(s):  
Hong Li ◽  
Jacqueline M Tremblay ◽  
Lynwood R Yarbrough ◽  
George M Helmkamp
Keyword(s):  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer

X-ray analysis of crystals of rat phosphatidylinositol-transfer protein with bound phosphatidylcholine

1999 ◽  
Vol 55 (2) ◽  
pp. 522-524 ◽  
Author(s):  
Randall L. Oliver ◽  
Jacqueline M. Tremblay ◽  
George M. Helmkamp ◽  
Lynwood R. Yarbrough ◽  
Natalie W. Breakfield ◽  
...  
Keyword(s):  
Crystal Form ◽  
Unit Cell ◽  
Asymmetric Unit ◽  
Unit Cell Parameters ◽  
Vapor Diffusion ◽  
Solvent Content ◽  
Cell Parameters ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer

Phosphatidylinositol-transfer protein (PITP) is a soluble, ubiquitously expressed, highly conserved protein encoded by two genes in humans, rodents and other mammals. A cDNA encoding the alpha isoform of the rat gene was expressed to high levels in Escherichia coli, the protein purified and the homogeneous protein used for crystallization studies. Crystals of rat PITP-α were obtained by vapor-diffusion techniques using the sitting-drop method. Crystals grow within two weeks by vapor-diffusion techniques in the presence of polyethylene glycol 4000. Both crystal forms pack in the monoclinic space group P21. Crystal form I has unit-cell parameters a = 44.75, b = 74.25, c = 48.32 Å and β = 114.14°. Unit-cell parameters for crystal form II are a = 47.86, b = 73.59, c = 80.49 Å and β = 98.54°. Crystal form I has a Vm of 2.295 Å3 Da−1 and an estimated solvent content of 46.4% with one molecule per asymmetric unit, while crystal form II has a Vm of 2.196 Å3 Da−1 and an estimated solvent content of 44.0%, assuming two molecules per asymmetric unit.

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