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Botella César, Jouhet Juliette, Maryse A Block
In plant cells, phosphatidylcholine (PC) is a major glycerolipid of most membranes but practically lacking from the plastid internal membranes. In chloroplasts, PC is absent from the thylakoids and the inner envelope membrane. It is however the main component of the outer envelope membrane, where it exclusively distributes in the outer monolayer. This unique distribution is likely related with operational compartmentalization of plant lipid metabolism. In this review, we summarize the different mechanisms involved in homeostasis of PC in plant cells...
November 18, 2016: Progress in Lipid Research
Hiroyuki Takatsu, Gaku Tanaka, Katsumori Segawa, Jun Suzuki, Shigekazu Nagata, Kazuhisa Nakayama, Hye-Won Shin
No abstract text is available yet for this article.
October 7, 2016: Journal of Biological Chemistry
Mauro C Wesseling, Lisa Wagner-Britz, Duc Bach Nguyen, Salome Asanidze, Judy Mutua, Nagla Mohamed, Benjamin Hanf, Mehrdad Ghashghaeinia, Lars Kaestner, Ingolf Bernhardt
BACKGROUND/AIMS: In previous publications we were able to demonstrate the exposure of phosphatidylserine (PS) in the outer membrane leaflet after activation of red blood cells (RBCs) by lysophosphatidic acid (LPA), phorbol-12 myristate-13acetate (PMA), or 4-bromo-A23187 (A23187). It has been concluded that three different mechanisms are responsible for the PS exposure in human RBCs: (i) Ca2+-stimulated scramblase activation (and flippase inhibition) by A23187, LPA, and PMA; (ii) PKCα activation by LPA and PMA; and (iii) enhanced lipid flip flop caused by LPA...
October 24, 2016: Cellular Physiology and Biochemistry
John Chu, Xavier Vila-Farres, Daigo Inoyama, Melinda Ternei, Louis J Cohen, Emma A Gordon, Boojala Vijay B Reddy, Zachary Charlop-Powers, Henry A Zebroski, Ricardo Gallardo-Macias, Mark Jaskowski, Shruthi Satish, Steven Park, David S Perlin, Joel S Freundlich, Sean F Brady
Here we present a natural product discovery approach, whereby structures are bioinformatically predicted from primary sequence and produced by chemical synthesis (synthetic-bioinformatic natural products, syn-BNPs), circumventing the need for bacterial culture and gene expression. When we applied the approach to nonribosomal peptide synthetase gene clusters from human-associated bacteria, we identified the humimycins. These antibiotics inhibit lipid II flippase and potentiate β-lactam activity against methicillin-resistant Staphylococcus aureus in mice, potentially providing a new treatment regimen...
December 2016: Nature Chemical Biology
Yuantai Wu, Mehmet Takar, Andrea A Cuentas-Condori, Todd R Graham
NEO1 is an essential gene in budding yeast and belongs to a highly conserved subfamily of P-type ATPase genes that encode phospholipid flippases. Inactivation of temperature sensitive neo1(ts) alleles produces pleiomorphic defects in the secretory and endocytic pathways, including fragmented vacuoles. A screen for multicopy suppressors of neo1-2(ts) growth defects yielded YPT7, which encodes a Rab7 homolog involved in SNARE-dependent vacuolar fusion. YPT7 suppressed the vacuole fragmentation phenotype of neo1-2, but did not suppress Golgi-associated protein trafficking defects...
July 2016: Cellular Logistics
Yoshiki Tanaka, Natsuki Ono, Takahiro Shima, Gaku Tanaka, Yohei Katoh, Kazuhisa Nakayama, Hiroyuki Takatsu, Hye-Won Shin
Type IV P-type ATPases (P4-ATPases) are phospholipid flippases that translocate phospholipids from the exoplasmic (or luminal) to the cytoplasmic leaflet of lipid bilayers. In Saccharomyces cerevisiae, P4-ATPases are localized to specific subcellular compartments and play roles in compartment-mediated membrane trafficking; however, roles of mammalian P4-ATPases in membrane trafficking are poorly understood. We previously reported that ATP9A, one of 14 human P4-ATPases, is localized to endosomal compartments and the Golgi complex...
December 1, 2016: Molecular Biology of the Cell
Bartholomew P Roland, Todd R Graham
Cellular membranes display a diversity of functions that are conferred by the unique composition and organization of their proteins and lipids. One important aspect of lipid organization is the asymmetric distribution of phospholipids (PLs) across the plasma membrane. The unequal distribution of key PLs between the cytofacial and exofacial leaflets of the bilayer creates physical surface tension that can be used to bend the membrane; and like Ca(2+), a chemical gradient that can be used to transduce biochemical signals...
October 4, 2016: Critical Reviews in Biochemistry and Molecular Biology
Qingxiang Zhou, Scott J Neal, Francesca Pignoni
A host of classical and molecular genetic tools make Drosophila a tremendous model for the dissection of gene activity. In particular, the FLP-FRT technique for mitotic recombination has greatly enhanced gene loss-of-function analysis. This technique efficiently induces formation of homozygous mutant clones in tissues of heterozygous organisms. However, the dependence of the FLP-FRT method on cell division, and other constraints, also impose limits on its effectiveness. We describe here the generation and testing of tools for Mutant Analysis by Rescue Gene Excision (MARGE), an approach whereby mutant cells are formed by loss of a rescue transgene in a homozygous mutant organism...
November 2016: Genesis: the Journal of Genetics and Development
Caitlin Deane
No abstract text is available yet for this article.
September 20, 2016: Nature Chemical Biology
Vincent A van der Mark, Mohammed Ghiboub, Casper Marsman, Jing Zhao, Remco van Dijk, Johan K Hiralall, Kam S Ho-Mok, Zoë Castricum, Wouter J de Jonge, Ronald P J Oude Elferink, Coen C Paulusma
P4-ATPases are lipid flippases that catalyze the transport of phospholipids to create membrane phospholipid asymmetry and to initiate the biogenesis of transport vesicles. Here we show, for the first time, that lipid flippases are essential to dampen the inflammatory response and to mediate the endotoxin-induced endocytic retrieval of Toll-like receptor 4 (TLR4) in human macrophages. Depletion of CDC50A, the β-subunit that is crucial for the activity of multiple P4-ATPases, resulted in endotoxin-induced hypersecretion of proinflammatory cytokines, enhanced MAP kinase signaling and constitutive NF-κB activation...
September 14, 2016: Cellular and Molecular Life Sciences: CMLS
Wael Elhenawy, Rebecca M Davis, Jutta Fero, Nina R Salama, Mario F Felman, Natividad Ruiz
The peptidoglycan (PG) cell wall is an essential component of the cell envelope of most bacteria. Biogenesis of PG involves a lipid-linked disaccharide-pentapeptide intermediate called lipid II, which must be translocated across the cytoplasmic membrane after it is synthesized in the inner leaflet of this bilayer. Accordingly, it has been demonstrated that MurJ, the proposed lipid II flippase in Escherichia coli, is required for PG biogenesis, and thereby viability. In contrast, MurJ is not essential in Bacillus subtilis because this bacterium produces AmJ, an unrelated protein that is functionally redundant with MurJ...
2016: PloS One
Mark P V Begieneman, Ellis N Ter Horst, Liza Rijvers, Elisa Meinster, Rene Leen, Jeanette Pankras, Jan Fritz, Bela Kubat, René J P Musters, Andre van Kuilenberg, Jan Stap, Hans W M Niessen, Paul A J Krijnen
AIMS: Excess catecholamine levels are suggested to be cardiotoxic and to underlie stress-induced heart failure. The cardiotoxic effects of noradrenaline and adrenaline are well recognized. However, although cardiac and circulating dopamine levels are also increased in stress-cardiomyopathy patients, knowledge regarding putative toxic effects of excess dopamine levels on cardiomyocytes is scarce. We now studied the effects of elevated dopamine levels in H9C2 cardiomyoblasts. METHODS AND RESULTS: H9C2 cells were cultured and treated with dopamine (200 μM) for 6, 24 and 48 hours...
August 12, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Jonathan Lombard
BACKGROUND: The N-glycosylation is an essential protein modification taking place in the membranes of the endoplasmic reticulum (ER) in eukaryotes and the plasma membranes in archaea. It shares mechanistic similarities based on the use of polyisoprenol lipid carriers with other glycosylation pathways involved in the synthesis of bacterial cell wall components (e.g. peptidoglycan and teichoic acids). Here, a phylogenomic analysis was carried out to examine the validity of rival hypotheses suggesting alternative archaeal or bacterial origins to the eukaryotic N-glycosylation pathway...
2016: Biology Direct
Jens P Andersen, Anna L Vestergaard, Stine A Mikkelsen, Louise S Mogensen, Madhavan Chalat, Robert S Molday
P4-ATPases comprise a family of P-type ATPases that actively transport or flip phospholipids across cell membranes. This generates and maintains membrane lipid asymmetry, a property essential for a wide variety of cellular processes such as vesicle budding and trafficking, cell signaling, blood coagulation, apoptosis, bile and cholesterol homeostasis, and neuronal cell survival. Some P4-ATPases transport phosphatidylserine and phosphatidylethanolamine across the plasma membrane or intracellular membranes whereas other P4-ATPases are specific for phosphatidylcholine...
2016: Frontiers in Physiology
Bartholomew P Roland, Todd R Graham
Phospholipid flippases in the type IV P-type ATPase (P4-ATPases) family establish membrane asymmetry and play critical roles in vesicular transport, cell polarity, signal transduction, and neurologic development. All characterized P4-ATPases flip glycerophospholipids across the bilayer to the cytosolic leaflet of the membrane, but how these enzymes distinguish glycerophospholipids from sphingolipids is not known. We used a directed evolution approach to examine the molecular mechanisms through which P4-ATPases discriminate substrate backbone...
August 2, 2016: Proceedings of the National Academy of Sciences of the United States of America
Hiroyuki Nakao, Keisuke Ikeda, Yasushi Ishihama, Minoru Nakano
The mechanism whereby phospholipids rapidly flip-flop in the endoplasmic reticulum (ER) membrane remains unknown. We previously demonstrated that the presence of a hydrophilic residue in the center of the model transmembrane peptide sequence effectively promoted phospholipid flip-flop and that hydrophilic residues composed 4.5% of the central regions of the membrane-spanning sequences of human ER membrane proteins predicted by SOSUI software. We hypothesized that ER proteins with hydrophilic residues might play a critical role in promoting flip-flop...
June 21, 2016: Biophysical Journal
Tobias Maetzig, Axel Schambach
Drug-inducible recombination based on flippase (FLP) is frequently used in animal models and in transgenic cell lines to initiate or to abrogate gene expression. Although the system is highly efficient, functional gene analyses depend on the availability of suitable animal models. In contrast, lentiviral vectors are readily available and versatile tools for the transfer of genetic information into a wide variety of target cells, and can be produced at high titer in a timely manner. To combine the advantages of both approaches, we generated a tight, drug-controlled FLP recombinase consisting of a 5' FKBP12 derived conditional destruction domain and a 3' estrogen receptor ligand binding (ERT2) domain...
2016: Methods in Molecular Biology
Vincent A van der Mark, Hugo R de Jonge, Jung-Chin Chang, Kam S Ho-Mok, Suzanne Duijst, Dragana Vidović, Marianne S Carlon, Ronald P J Oude Elferink, Coen C Paulusma
Progressive familial intrahepatic cholestasis type 1 (PFIC1) is caused by mutations in the gene encoding the phospholipid flippase ATP8B1. Apart from severe cholestatic liver disease, many PFIC1 patients develop extrahepatic symptoms characteristic of cystic fibrosis (CF), such as pulmonary infection, sweat gland dysfunction and failure to thrive. CF is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel essential for epithelial fluid transport. Previously it was shown that CFTR transcript levels were strongly reduced in livers of PFIC1 patients...
September 2016: Biochimica et Biophysica Acta
Frederica L Theodoulou, David J Carrier, Theresia A Schaedler, Stephen A Baldwin, Alison Baker
Import of β-oxidation substrates into peroxisomes is mediated by ATP binding cassette (ABC) transporters belonging to subfamily D. In order to enter the β-oxidation pathway, fatty acids are activated by conversion to fatty acyl-CoA esters, a reaction which is catalysed by acyl-CoA synthetases (ACSs). Here, we present evidence for an unusual transport mechanism, in which fatty acyl-CoA substrates are accepted by ABC subclass D protein (ABCD) transporters, cleaved by the transporters during transit across the lipid bilayer to release CoA, and ultimately re-esterified in the peroxisome lumen by ACSs which interact with the transporter...
June 15, 2016: Biochemical Society Transactions
Maria S Jensen, Sara R Costa, Lisa Theorin, Jan Pravsgaard Christensen, Thomas Günther Pomorski, Rosa L López-Marqués
Lipid flippases are integral membrane proteins that play a central role in moving lipids across cellular membranes. Some of these transporters are ATPases that couple lipid translocation to ATP hydrolysis, whereas others function without any discernible metabolic energy input. A growing number of lipid flippases has been identified but key features of their activity remain to be elucidated. A well-established method to characterize ATP-driven flippases is based on their heterologous expression in yeast, followed by incubation of the cells with fluorescent lipids...
July 2016: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
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