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SMAC/Diablo controls proliferation of cancer cells by regulating phosphatidylethanolamine synthesis.Molecular Oncology Nov 2021SMAC/Diablo, a pro-apoptotic protein, yet it is overexpressed in several cancer types. We have described a noncanonical function for SMAC/Diablo as a regulator of lipid...
SMAC/Diablo, a pro-apoptotic protein, yet it is overexpressed in several cancer types. We have described a noncanonical function for SMAC/Diablo as a regulator of lipid synthesis during cancer cell proliferation and development. Here, we explore the molecular mechanism through which SMAC/Diablo regulates phospholipid synthesis. We showed that SMAC/Diablo directly interacts with mitochondrial phosphatidylserine decarboxylase (PSD) and inhibits its catalytic activity during synthesis of phosphatidylethanolamine (PE) from phosphatidylserine (PS). Unlike other phospholipids (PLs), PE is synthesized not only in the endoplasmic reticulum but also in mitochondria. As a result, PSD activity and mitochondrial PE levels were increased in the mitochondria of SMAC/Diablo-deficient cancer cells, with the total amount of cellular PLs and phosphatidylcholine (PC) being lower as compared to SMAC-expressing cancer cells. Moreover, in the absence of SMAC/Diablo, PSD inhibited cancer cell proliferation by catalysing the overproduction of mitochondrial PE and depleting the cellular levels of PC, PE and PS. Additionally, we demonstrated that both SMAC/Diablo and PSD colocalization in the nucleus resulted in increased levels of nuclear PE, that acts as a signalling molecule in regulating several nuclear activities. By using a peptide array composed of 768-peptides derived from 11 SMAC-interacting proteins, we identified six nuclear proteins ARNT, BIRC2, MAML2, NR4A1, BIRC5 and HTRA2 Five of them also interacted with PSD through motifs that are not involved in SMAC binding. Synthetic peptides carrying the PSD-interacting motifs of these proteins could bind purified PSD and inhibit the PSD catalytic activity. When targeted specifically to the mitochondria or the nucleus, these synthetic peptides inhibited cancer cell proliferation. To our knowledge, these are the first reported inhibitors of PSD acting also as inhibitors of cancer cell proliferation. Altogether, we demonstrated that phospholipid metabolism and PE synthesis regulated by the SMAC-PSD interaction are essential for cancer cell proliferation and may be potentially targeted for treating cancer.
Topics: Apoptosis; Apoptosis Regulatory Proteins; Cell Proliferation; Humans; Intracellular Signaling Peptides and Proteins; Mitochondrial Proteins; Neoplasms; Phosphatidylethanolamines
PubMed: 33794068
DOI: 10.1002/1878-0261.12959 -
Analytical Chemistry Aug 2020Direct interspecies electron transfer (DIET) has been considered as a novel and highly efficient strategy in both natural anaerobic environments and artificial microbial...
Direct interspecies electron transfer (DIET) has been considered as a novel and highly efficient strategy in both natural anaerobic environments and artificial microbial fuel cells. A syntrophic model consisting of and was studied in this work. We conducted in vivo molecular mapping of the outer surface of the syntrophic community as the interface of nutrients and energy exchange. System for Analysis at the Liquid Vacuum Interface combined with time-of-flight secondary ion mass spectrometry was employed to capture the molecular distribution of syntrophic communities in the living and hydrated state. Principal component analysis with selected peaks revealed that syntrophic aggregates were well differentiated from other control samples, including syntrophic planktonic cells, pure cultured planktonic cells, and single population biofilms. Our in vivo imaging indicated that a unique molecular surface was formed. Specifically, aromatic amino acids, phosphatidylethanolamine components, and large water clusters were identified as key components that favored the DIET of syntrophic aggregates. Moreover, the molecular changes in depths of the aggregates were captured using dynamic depth profiling. Our findings shed new light on the interface components supporting electron transfer in syntrophic communities based on in vivo molecular imaging.
Topics: Amino Acids, Aromatic; Biofilms; Electron Transport; Geobacter; Mass Spectrometry; Molecular Imaging; Phosphatidylethanolamines; Principal Component Analysis; Water
PubMed: 32614167
DOI: 10.1021/acs.analchem.0c00653 -
International Journal of Systematic and... Jul 2021A Gram-stain-negative, oxidase-positive, catalase-positive, aerobic, orange-pigmented, rod-shaped and non-motile bacterium designated strain MMS17-SY002 was isolated...
A Gram-stain-negative, oxidase-positive, catalase-positive, aerobic, orange-pigmented, rod-shaped and non-motile bacterium designated strain MMS17-SY002 was isolated from island soil. The isolate grew at 20-37 °C (optimum, 30 °C), at pH 6.0-9.5 (optimum, pH 7) and in the presence of 0.5-4.0 % (w/v) NaCl (optimum, 2.0 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MMS17-SY002 was mostly related to the genus of the family and had highest sequence similarity of 96.82 % to A6B8 and EM44, but formed a distinct phylogenetic line within the genus. Chemotaxonomic analyses showed that menaquinone 6 was the predominant isoprenoid quinone, the major fatty acids were iso-C G and iso-C, and the diagnostic polar lipid was phosphatidylethanolamine. The genomic DNA G+C content was 42.4 mol%. Strain MMS17-SY002 could be distinguished from related species by the combination of trypsin, α-chymotrypsin, acid phosphatase, naphthol-AS-BI-phosphohydrolase, α-galactosidase, β-galactosidase and β-glucosidase activities. The orthologous average nucleotide identity between the genomes of strain MMS17-SY002 and and that between the strain and A6B8 were 73.26 and 73.33%, respectively, thus confirming the separation of the strain from related species at species level. Based on the phenotypic, phylogenetic, chemotaxonomic and genomic characterization, MMS17-SY002 should be recognized as a novel species of the genus , for which the name sp. nov. is proposed. The type strain is MMS17-SY002 (=KCTC 62790=JCM 32370).
Topics: Bacterial Typing Techniques; Base Composition; DNA, Bacterial; Fatty Acids; Flavobacteriaceae; Islands; Phosphatidylethanolamines; Phylogeny; Pigmentation; RNA, Ribosomal, 16S; Republic of Korea; Sequence Analysis, DNA; Soil Microbiology; Vitamin K 2
PubMed: 34270398
DOI: 10.1099/ijsem.0.004887 -
Biochimica Et Biophysica Acta.... Feb 2018Most biomembranes have an asymmetric structure with regard to phospholipid distribution between the inner and outer leaflets of the lipid bilayers. Control of the...
Most biomembranes have an asymmetric structure with regard to phospholipid distribution between the inner and outer leaflets of the lipid bilayers. Control of the asymmetric distribution plays a pivotal role in several cellular functions such as intracellular membrane fusion and cell division. The mechanism by which membrane asymmetry and its alteration function in these transformation processes is not yet clear. To understand the significance of membrane asymmetry on trafficking and metabolism of intracellular vesicular components, a system that experimentally reproduces the asymmetric nature of biomembranes is essential. Here, we succeeded in obtaining asymmetric vesicles by means of transphosphatidylation reactions with phospholipase D (PLD), which acts exclusively on phosphatidylcholine (PC) present in the outer leaflet of vesicles. By treating PC vesicles with PLD in the presence of 1.7M serine and 0.3M ethanolamine, we obtained asymmetric vesicles that are topologically similar to intracellular vesicles containing phosphatidylserine and phosphatidylethanolamine in the cytosolic leaflet. PLD and other unwanted compounds could be removed by trypsin digestion followed by dialysis. Our established technique has a great advantage over conventional methods in that asymmetric vesicles can be provided at high yield and high efficiency, which is requisite for most physicochemical assays.
Topics: Cell Membrane; Cytoplasmic Vesicles; Lipid Bilayers; Membrane Fusion; Models, Chemical; Molecular Structure; Phosphatidylcholines; Phosphatidylethanolamines; Phosphatidylserines; Phospholipase D; Phospholipids; Spectrometry, Fluorescence
PubMed: 29032301
DOI: 10.1016/j.bbamem.2017.10.011 -
Presse Medicale (Paris, France : 1983) Mar 2015Antibody to phosphatidylethanolamine (aPE) are observed in thrombotic or obstetric manifestations suggestive of antiphospholipid syndrome (APS). aPE seem to be markers... (Review)
Review
Antibody to phosphatidylethanolamine (aPE) are observed in thrombotic or obstetric manifestations suggestive of antiphospholipid syndrome (APS). aPE seem to be markers of thrombotic risk independent of conventional antiphospholipid antibodies (aPL). aPE assays are not standardized. There is no therapeutic recommendation for isolated aPE patients with thrombotic or obstetric events. Prospective studies have to be carried to better define the therapeutic management of these patients. Value of aPE in APS criteria is still not established.
Topics: Antibodies, Antiphospholipid; Antiphospholipid Syndrome; Biomarkers; Female; Humans; Phosphatidylethanolamines; Pregnancy; Pregnancy Complications; Thrombosis
PubMed: 25542711
DOI: 10.1016/j.lpm.2014.06.033 -
Nature Communications Jan 2018Macroautophagy (autophagy) is a crucial cellular stress response for degrading defective macromolecules and organelles, as well as providing bioenergetic intermediates...
Macroautophagy (autophagy) is a crucial cellular stress response for degrading defective macromolecules and organelles, as well as providing bioenergetic intermediates during hypoxia and nutrient deprivation. Here we report a thiol-dependent process that may account for impaired autophagy during aging. This is through direct oxidation of key autophagy-related (Atg) proteins Atg3 and Atg7. When inactive Atg3 and Atg7 are protected from oxidation due to stable covalent interaction with their substrate LC3. This interaction becomes transient upon activation of Atg3 and Atg7 due to transfer of LC3 to phosphatidylethanolamine (lipidation), a process crucial for functional autophagy. However, loss in covalent-bound LC3 also sensitizes the catalytic thiols of Atg3 and Atg7 to inhibitory oxidation that prevents LC3 lipidation, observed in vitro and in mouse aorta. Here findings provide a thiol-dependent process for negatively regulating autophagy that may contribute to the process of aging, as well as therapeutic targets to regulate autophagosome maturation.
Topics: Aging; Animals; Aorta; Autophagosomes; Autophagy; Autophagy-Related Protein 7; Autophagy-Related Proteins; HEK293 Cells; Humans; Hydrogen Peroxide; Male; Mice, Inbred C57BL; Microtubule-Associated Proteins; Myocytes, Smooth Muscle; Oxidation-Reduction; Phosphatidylethanolamines; Primary Cell Culture; Rats; Sulfhydryl Compounds; Ubiquitin-Conjugating Enzymes
PubMed: 29311554
DOI: 10.1038/s41467-017-02352-z -
Physical Chemistry Chemical Physics :... Sep 2022In certain bacteria, phosphatidylethanolamine lipids (PEL) get largely replaced by phosphate-free ornithine lipids (OL) under conditions of phosphate starvation. It has...
In certain bacteria, phosphatidylethanolamine lipids (PEL) get largely replaced by phosphate-free ornithine lipids (OL) under conditions of phosphate starvation. It has so far been unknown how much these two lipid types deviate in their physicochemical properties, and how strongly bacteria thus have to adapt in order to compensate for the difference. Here, we use differential scanning calorimetry, X-ray scattering, and X-ray fluorescence to investigate the properties of OL with saturated C14 alkyl chains in mono- and bilayers. OL is found to have a greater tendency than chain-analogous PEL to form ordered structures and, in contrast to PEL, even a molecular superlattice based on a hydrogen bonding network between the headgroups. This superlattice is virtually electrically uncharged and persists over a wide pH range. Our results indicate that OL and PEL behave very differently in ordered single-component membranes but may behave more similarly in fluid multicomponent membranes.
Topics: Calorimetry, Differential Scanning; Hydrogen-Ion Concentration; Lipid Bilayers; Lipids; Ornithine; Phosphatidylethanolamines
PubMed: 36111816
DOI: 10.1039/d2cp01045c -
Structure (London, England : 1993) Jul 2020In both prokaryotes and eukaryotes, phosphatidylethanolamine (PE), one of the most abundant membrane phospholipids, plays important roles in various membrane functions...
In both prokaryotes and eukaryotes, phosphatidylethanolamine (PE), one of the most abundant membrane phospholipids, plays important roles in various membrane functions and is synthesized through the decarboxylation of phosphatidylserine (PS) by PS decarboxylases (PSDs). However, the catalysis and substrate recognition mechanisms of PSDs remain unclear. In this study, we focused on the PSD from Escherichia coli (EcPsd) and determined the crystal structures of EcPsd in the apo form and PE-bound form at resolutions of 2.6 and 3.6 Å, respectively. EcPsd forms a homodimer, and each protomer has a positively charged substrate binding pocket at the active site. Structure-based mutational analyses revealed that conserved residues in the pocket are involved in PS decarboxylation. EcPsd has an N-terminal hydrophobic helical region that is important for membrane binding, thereby achieving efficient PS recognition. These results provide a structural basis for understanding the mechanism of PE biosynthesis by PSDs.
Topics: Binding Sites; Carboxy-Lyases; Cell Membrane; Conserved Sequence; Escherichia coli; Escherichia coli Proteins; Mutation; Phosphatidylethanolamines; Phosphatidylserines; Protein Binding
PubMed: 32402247
DOI: 10.1016/j.str.2020.04.006 -
Biochimica Et Biophysica Acta.... Aug 2021Recently, we reported that a ternary lipid bilayer comprising phosphatidylethanolamine (PE), phosphatidylcholine (PC), which were both derived from chicken egg, and...
Recently, we reported that a ternary lipid bilayer comprising phosphatidylethanolamine (PE), phosphatidylcholine (PC), which were both derived from chicken egg, and cholesterol (Chol) generates microdomains that function as specific fusion sites for proteoliposomes. Chol-induced microdomain formation in a completely miscible lipid bilayer is an exceptional phenomenon. Numerous studies have elucidated the formation of domains in liquid ordered (L) and liquid disordered (L) phases of ternary bilayers, which comprise two partially miscible lipids and Chol. Herein, we investigated the composition and mechanism of formation of these unique microdomains in supported lipid bilayers (SLBs) using a fluorescence microscope and an atomic force microscope (AFM). We prepared ternary SLBs using egg-derived PC (eggPC), Chol and three different types of PE: egg-derived PE, 1-palmitoyl-2-oleoyl-PE, and 1,2-didocosahexaenoyl-PE (diDHPE). Fluorescence microscopy observations revealed that fluid and continuous SLBs were formed at PE concentrations (C) of ≥6 mol%. Fluorescence recovery after photobleaching measurement revealed that the microdomain was more fluid than the surrounding region that showed typical diffusion coefficient of the L phase. The microdomains were observed as depressions in the AFM topographies. Their area fraction (θ) increased with C, and diDHPE produced a significantly large θ among the three PEs. The microdomains in the PE+eggPC+Chol-SLBs were rich in polyunsaturated PE and were in the L-like phase. Associating eggPC and Chol caused polyunsaturated PE to segregate, resulting in a microdomain formation by conferring the umbrella effect on Chol, entropic effect of disordered acyl chains, and π-π interactions in the hydrophobic core.
Topics: Cholesterol; Lipid Bilayers; Membrane Microdomains; Microscopy, Fluorescence; Phosphatidylcholines; Phosphatidylethanolamines; Phospholipids
PubMed: 33901442
DOI: 10.1016/j.bbamem.2021.183626 -
The Journal of Biological Chemistry Feb 2018Phosphatidylserine decarboxylases (PSDs) are central enzymes in phospholipid metabolism that produce phosphatidylethanolamine (PE) in bacteria, protists, plants, and...
Phosphatidylserine decarboxylases (PSDs) are central enzymes in phospholipid metabolism that produce phosphatidylethanolamine (PE) in bacteria, protists, plants, and animals. We developed a fluorescence-based assay for selectively monitoring production of PE in reactions using a maltose-binding protein fusion with PSD (MBP-His-Δ34PkPSD) as the enzyme. The PE detection by fluorescence (λ = 403 nm, λ = 508 nm) occurred after the lipid reacted with a water-soluble distyrylbenzene-bis-aldehyde (DSB-3), and provided strong discrimination against the phosphatidylserine substrate. The reaction conditions were optimized for enzyme, substrate, product, and DSB-3 concentrations with the purified enzyme and also tested with crude extracts and membrane fractions from bacteria and yeast. The assay is readily amenable to application in 96- and 384-well microtiter plates and should prove useful for high-throughput screening for inhibitors of PSD enzymes across diverse phyla.
Topics: Carboxy-Lyases; Fluorescence; Maltose-Binding Proteins; Phosphatidylethanolamines; Plasmodium knowlesi; Protozoan Proteins; Recombinant Fusion Proteins
PubMed: 29247006
DOI: 10.1074/jbc.RA117.000525