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 Phospholipid transfer proteins revisited

1997 ◽  
Vol 324 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Karel. W. A WIRTZ
Keyword(s):  
Mammalian Cells ◽  
Lipid Transfer Protein ◽  
Fusion Reaction ◽  
Lipid Binding ◽  
Lipid Transfer ◽  
Cell Functions ◽  
Transfer Protein ◽  
Phospholipid Transfer ◽  
Phosphatidylinositol Transfer

Phosphatidylinositol transfer protein (PI-TP) and the non-specific lipid transfer protein (nsL-TP) (identical with sterol carrier protein 2) belong to the large and diverse family of intracellular lipid-binding proteins. Although these two proteins may express a comparable phospholipid transfer activity in vitro, recent studies in yeast and mammalian cells have indicated that they serve completely different functions. PI-TP (identical with yeast SEC14p) plays an important role in vesicle flow both in the budding reaction from the trans-Golgi network and in the fusion reaction with the plasma membrane. In yeast, vesicle budding is linked to PI-TP regulating Golgi phosphatidylcholine (PC) biosynthesis with the apparent purpose of maintaining an optimal PI/PC ratio of the Golgi complex. In mammalian cells, vesicle flow appears to be dependent on PI-TP stimulating phosphatidylinositol 4,5-bisphosphate (PIP2) synthesis. This latter process may also be linked to the ability of PI-TP to reconstitute the receptor-controlled PIP2-specific phospholipase C activity. The nsL-TP is a peroxisomal protein which, by its ability to bind fatty acyl-CoAs, is most likely involved in the β-oxidation of fatty acids in this organelle. This protein constitutes the N-terminus of the 58 kDa protein which is one of the peroxisomal 3-oxo-acyl-CoA thiolases. Further studies on these and other known phospholipid transfer proteins are bound to reveal new insights in their important role as mediators between lipid metabolism and cell functions.

In vivo and in vitro techniques in the diagnosis of lipid transfer protein sensitization

2013 ◽  
Vol 111 (6) ◽  
pp. 571-573 ◽  
Author(s):  
Felicia Berroa ◽  
Gabriel Gastaminza ◽  
Noemí Saiz ◽  
Julián Azofra ◽  
Pedro M. Gamboa ◽  
...  
Keyword(s):  
Lipid Transfer Protein ◽  
Lipid Transfer ◽  
In Vitro Techniques ◽  
Transfer Protein ◽  
Protein Sensitization

Phosphatidylinositol-transfer protein and its homologues in yeast

2006 ◽  
Vol 34 (3) ◽  
pp. 377-380 ◽  
Author(s):  
P. Griac ◽  
R. Holic ◽  
D. Tahotna
Keyword(s):  
Membrane Trafficking ◽  
Diverse Group ◽  
Secretory Function ◽  
Lipid Transfer ◽  
Lipid Transfer Proteins ◽  
Transfer Protein ◽  
Phosphatidylinositol Transfer ◽  
Phosphatidylcholine Transfer Protein

Yeast Sec14p acts as a phosphatidylinositol/phosphatidylcholine-transfer protein in vitro. In vivo, it is essential in promoting Golgi secretory function. Products of five genes named SFH1–SFH5 (Sec Fourteen Homologues 1–5) exhibit significant sequence homology to Sec14p and together they form the Sec14p family of lipid-transfer proteins. It is a diverse group of proteins with distinct subcellular localizations and varied physiological functions related to lipid metabolism and membrane trafficking.

scholarly journals Deletion of 24 amino acids from the C-terminus of phosphatidylinositol transfer protein causes loss of phospholipase C-mediated inositol lipid signalling

1997 ◽  
Vol 324 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Simon PROSSER ◽  
Robert SARRA ◽  
Philip SWIGART ◽  
Andrew BALL ◽  
Shamshad COCKCROFT
Keyword(s):  
Amino Acids ◽  
Phospholipase C ◽  
Size Exclusion ◽  
Lipid Transfer ◽  
Transfer Protein ◽  
C Terminus ◽  
Phosphatidylinositol Transfer Protein ◽  
Phosphatidylinositol Transfer

Phosphatidylinositol transfer protein α (PITPα) is a 32 kDa protein of 270 amino acids that is essential for phospholipase C-mediated phosphatidylinositol bisphosphate hydrolysis. In addition, it binds and transfers phosphatidylinositol and phosphatidylcholine between membrane compartments in vitro. Here we have used limited proteolysis of PITPα by subtilisin to identify the structural requirements for function. Digestion by subtilisin results in the generation of a number of slightly smaller peptide fragments, the major fragment being identified as a 29 kDa protein. The fragments were resolved by size-exclusion chromatography and were found to be totally inactive in both in vivo PLC reconstitution assays and in vitro phosphatidylinositol transfer assays. N-terminal sequencing and MS of the major 29 kDa fragment shows that cleavage occurs at the C-terminus of PITP at Met246, leading to a deletion of 24 amino acid residues. We conclude that the C-terminus plays an important role in mediating PLC signalling in vivo and lipid transfer in vitro, supporting the notion that lipid transfer may be a facet of PITP function in vivo.

scholarly journals Interdomain interactions regulate the localization of a lipid transfer protein at ER-PM contact sites

2020 ◽  
Author(s):  
Bishal Basak ◽  
Harini Krishnan ◽  
Padinjat Raghu
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Transfer Protein ◽  
Intramolecular Interaction ◽  
Lipid Transfer ◽  
Loss Of Function ◽  
Transfer Protein ◽  
Contact Sites ◽  
Accurate Localization ◽  
Phosphatidylinositol Transfer ◽  
Interdomain Interactions

Abstract During phospholipase C-β (PLC-β) signalling in Drosophila photoreceptors, the phosphatidylinositol transfer protein (PITP) RDGB, is required for lipid transfer at endoplasmic reticulum (ER)-plasma membrane (PM) contact sites (MCS). Depletion of RDGB or its mis-localization away from the ER-PM MCS results in multiple defects in photoreceptor function. Previously, the interaction between the FFAT motif of RDGB and the integral ER protein dVAP-A was shown to be essential for accurate localization to ER-PM MCS. Here, we report that the FFAT/dVAP-A interaction alone is insufficient to localize RDGB accurately; this also requires the function of the C-terminal domains, DDHD and LNS2. Mutations in each of these domains results in mis-localization of RDGB leading to loss of function. While the LNS2 domain is necessary, it is not sufficient for the correct localization of RDGB, which also requires the C-terminal DDHD domain. The function of the DDHD domain is mediated through an intramolecular interaction with the LNS2 domain. Thus, interactions between the additional domains in a multi-domain PITP together lead to accurate localization at the MCS and signalling function.

scholarly journals The Medicago truncatula N5 Gene Encoding a Root-Specific Lipid Transfer Protein Is Required for the Symbiotic Interaction with Sinorhizobium meliloti

2009 ◽  
Vol 22 (12) ◽  
pp. 1577-1587 ◽  
Author(s):  
Youry Pii ◽  
Alessandra Astegno ◽  
Elisa Peroni ◽  
Massimo Zaccardelli ◽  
Tiziana Pandolfini ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Sinorhizobium Meliloti ◽  
Lipid Transfer Protein ◽  
Symbiotic Association ◽  
Lipid Transfer ◽  
Symbiotic Interaction ◽  
Transgenic Roots ◽  
Transfer Protein ◽  
Small Proteins

The Medicago truncatula N5 gene is induced in roots after Sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (LTP), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. Various biological roles for plant LTP in vivo have been proposed, including defense against pathogens and modulation of plant development. The aim of this study was to shed light on the role of MtN5 in the symbiotic interaction between M. truncatula and S. meliloti. MtN5 cDNA was cloned and the mature MtN5 protein expressed in Escherichia coli. The lipid binding capacity and antimicrobial activity of the recombinant MtN5 protein were tested in vitro. MtN5 showed the capacity to bind lysophospholipids and to inhibit M. truncatula pathogens and symbiont growth in vitro. Furthermore, MtN5 was upregulated in roots after infection with either the fungal pathogen Fusarium semitectum or the symbiont S. meliloti. Upon S. meliloti infection, MtN5 was induced starting from 1 day after inoculation (dpi). It reached the highest concentration at 3 dpi and it was localized in the mature nodules. MtN5-silenced roots were impaired in nodulation, showing a 50% of reduction in the number of nodules compared with control roots. On the other hand, transgenic roots overexpressing MtN5 developed threefold more nodules with respect to control roots. Here, we demonstrate that MtN5 possesses biochemical features typical of LTP and that it is required for the successful symbiotic association between M. truncatula and S. meliloti.

Abstract 319: Dalcetrapib-Mediated Modulation of Cholesteryl Ester Transfer Protein Activity Increases HDL-Cholesterol, Apolipoprotein A-I Levels and Cholesterol Efflux Capacity in Chow-Fed Rabbits

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Mathieu R Brodeur ◽  
David Rhainds ◽  
Daniel Charpentier ◽  
Téodora Mihalache-Avram ◽  
Cyrille Maugeais ◽  
...  
Keyword(s):  
Cholesteryl Ester ◽  
Cholesteryl Ester Transfer Protein ◽  
Cholesterol Efflux ◽  
Hdl Cholesterol ◽  
Lipid Transfer ◽  
Protein Activity ◽  
Cholesterol Efflux Capacity ◽  
Transfer Protein

Introduction: A potential approach to reduce CV risk is to increase HDL-C levels. This could be achieved by reducing cholesteryl ester transfer protein (CETP) activity. Dalcetrapib, which modulates CETP activity by changing its conformation and raises HDL-C without inhibiting CETP-induced pre-β-HDL formation in humans, was shown to decrease progression of atherosclerosis in rabbits. Hypothesis: Investigate the modifications of HDL particle size distribution and cholesterol efflux capacity of serum produced by dalcetrapib in normocholesterolemic rabbits. Methods: New Zealand white rabbits were treated with dalcetrapib (300 mg/kg as food admix) or placebo for 14 days. We evaluated CETP conformation and mass by ELISAs (including antibodies sensitive to conformational change), CETP activity by fluorescent lipid transfer, lipid profile and apoA-I distribution in HDL subclasses by 2D-non denaturing gradient gels (2D-NDGGE). Cholesterol efflux capacity of rabbit sera was determined after loading cells with 3 H-free cholesterol, using HepG2 hepatocytes to measure SR-BI-dependent efflux and by inducing ABCA1 or ABCG1 expression in BHK cells. Results: Dalcetrapib modified the conformation of rabbit CETP in vitro and in vivo and, after 14 days, this was associated with increased CETP mass (+50%, p<0.001) and reduced CETP activity (-86%, p<0.001). Total cholesterol was increased with dalcetrapib (+178%, p<0.001), due to a higher HDL-C level. In contrast, dalcetrapib reduced LDL-C and triglycerides by 41% (p<0.01) and 48% (p<0.001). Serum analysis by 2D-NDGGE showed that total rabbit apoA-I was increased 1.7- fold in animals treated with dalcetrapib. This was associated with an increase in large HDL but also in small α-migrating HDL with pre-β-HDL size. Cholesterol efflux assays showed that ABCA1-, ABCG1- and SR-BI-dependent efflux were all increased in dalcetrapib-treated rabbits (+24%, p=0.038; +21%, p=0.021; +44%, p<0.001). Conclusion: Modulation of CETP activity and conformation by dalcetrapib increases HDL-C and apoA-I levels and affects apoA-I distribution in HDL subclasses. These changes are associated with increased cholesterol efflux capacity, suggesting that HDL functionality is preserved in dalcetrapib-treated chow-fed rabbits.

scholarly journals Human CETP lacks lipopolysaccharide transfer activity, but worsens inflammation and sepsis outcomes in mice

2020 ◽  
pp. jlr.RA120000704
Author(s):  
Aloïs Dusuel ◽  
Valérie Deckert ◽  
Jean-Paul PAIS DE BARROS ◽  
Kevin Van Dongen ◽  
Hélène Choubley ◽  
...  
Keyword(s):  
Cecal Ligation ◽  
Plasma Lipid ◽  
Plasma Lipoproteins ◽  
Protective Effects ◽  
Lipid Transfer ◽  
Transfer Property ◽  
Transfer Activity ◽  
Lps Binding

Bacterial lipopolysaccharides (LPSs or endotoxins) can bind most proteins of the lipid transfer/LPS-binding protein (LT/LBP) family in host organisms. The LPS-bound LT/LBP proteins then trigger either an LPS-induced proinflammatory cascade or LPS binding to lipoproteins that are involved in endotoxin inactivation and detoxification. Cholesteryl ester transfer protein (CETP) is an LT/LBP member, but its impact on LPS metabolism and sepsis outcome is unclear. Here, we performed fluorescent LPS transfer assays to assess the ability of CETP to bind and transfer LPS. The effects of intravenous (iv) infusion of purified LPS or polymicrobial infection (cecal ligation and puncture [CLP]) were compared in transgenic mice expressing human CETP and wild-type mice naturally having no CETP activity. CETP displayed no LPS transfer activity in vitro, but it tended to reduce biliary excretion of LPS in vivo. The CETP expression in mice was associated with significantly lower basal plasma lipid levels and with higher mortality rates in both models of endotoxemia and sepsis. Furthermore, CETPTg plasma modified cytokine production of macrophages in vitro. In conclusion, despite having no direct LPS binding and transfer property, human CETP worsens sepsis outcomes in mice by altering the protective effects of plasma lipoproteins against endotoxemia, inflammation, and infection.

scholarly journals Biochemical analysis of antimicrobial peptides in two different Capsicum genotypes after fruit infection by Colletotrichum gloeosporioides

2019 ◽  
Vol 39 (4) ◽  
Author(s):  
Álan C. Maracahipes ◽  
Gabriel B. Taveira ◽  
Erica O. Mello ◽  
André O. Carvalho ◽  
Rosana Rodrigues ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Colletotrichum Gloeosporioides ◽  
Protein Extraction ◽  
Lipid Transfer Protein ◽  
Extraction Process ◽  
Lipid Transfer ◽  
Protease Inhibition ◽  
Transfer Protein ◽  
Trypsin Inhibition

Abstract There are several phytosanitary problems that have been causing serious damage to the Capsicum crops, including anthracnose. Upon attack by certain pathogens, various protein molecules are produced, which are known as proteins related to pathogenesis (PR proteins), including antimicrobial peptides such as protease inhibitors, defensins and lipid transfer proteins (LTPs). The objective of this work is to identify antimicrobial proteins and/or peptides of two genotypes from Capsicum annuum fruits infected with Colletotrichum gloeosporioides. The fungus was inoculated into Capsicum fruits by the deposition of a spore suspension (106 conidia ml−1), and after 24 and 48 h intervals, the fruits were removed from the humid chamber and subjected to a protein extraction process. Protein analysis of the extracts was performed by tricine gel electrophoresis and Western blotting. The distinctive bands between genotypes in the electrophoresis profiles were subjected to mass spectrometry sequencing. Trypsin inhibition assays, reverse zymographic detection of protease inhibition and β-1,3-glucanase activity assays were also performed and extracts were also tested for their ability to inhibit the growth of C. gloeosporioides fungi ‘in vitro’. There were several low molecular weight proteins in all treated samples, and some treatments in which antimicrobial peptides such as defensin, lipid transfer protein (LTP) and protease inhibitor have been identified. It was shown that the green fruits are more responsive to infection, showing the production of antimicrobial peptides in response to injury and inoculation of the fungus, what did not occur in ripe fruits under any treatment.

Sign in / Sign up

Export Citation Format

Share Document