Phospholipases D (PLDs) catabolize structural phospholipids to produce phosphatidic acid (PtdOH), a lipid playing central role in signalling pathways in animal, yeast and plant cells. In animal cells two PLD genes have been studied while in model plant twelve genes exist, classified in six classes (α-ζ). This underlines the role of these enzymes in plant responses to environmental stresses.
View Article and Find Full Text PDFBackground: The complexity of phosphoinositide signaling in higher eukaryotes is partly due to expansion of specific families and types of phosphoinositide kinases (PIKs) that can generate all phosphoinositides via multiple routes. This is particularly evident in the PI3Ks and PIPKs, and it is considered an evolutionary trait associated with metazoan diversification. Yet, there are limited comprehensive studies on the PIK repertoire of free living unicellular organisms.
View Article and Find Full Text PDFCommun Integr Biol
September 2011
Phospholipases C (PLCs) that hydrolyze inositol phospholipids regulate vital cellular functions in both eukaryotic and prokaryotic organisms. The PLC superfamily consists of eukaryotic phosphoinositide-specific PLCs (PI-PLCs), bacterial PLCs and trypanosomal PLCs.1 PI-PLCs hydrolyze phosphatidylinositol-4,5-bisphosphate (PtdIns4,5P(2)) to produce inositol-1,4,5-trisphosphate (Ins1,4,5P(3)) and constitute a hallmark feature of eukaryotic cells.
View Article and Find Full Text PDFEukaryotic phosphoinositide-specific phospholipases C (PI-PLC) specifically hydrolyze phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)], produce the Ca(2+)-mobilizing agent inositol 1,4,5-trisphosphate, and regulate signaling in multicellular organisms. Bacterial PtdIns-specific PLCs, also present in trypanosomes, hydrolyze PtdIns and glycosyl-PtdIns, and they are considered important virulence factors. All unicellular eukaryotes studied so far contain a single PI-PLC-like gene.
View Article and Find Full Text PDFPhospholipase Dalpha (PLDalpha) was isolated from cultivated cotton (Gossypium hirsutum) and characterized. Two PLDalpha genes were identified in the allotetraploid genome of G. hirsutum, derived from its diploid progenitors, G.
View Article and Find Full Text PDFAflatoxin B(1) (AFB(1)) is a carcinogenic metabolite produced by certain Aspergillus species on agricultural commodities. AFB(1) biosynthesis is affected by jasmonic acid and also by its methylester (MeJA), a plant growth regulator derived from linoleic acid. This study reports the effect of MeJA on the growth of A.
View Article and Find Full Text PDFLung surfactant (LS) is a lipid-rich material lining the inside of the lungs. It reduces surface tension at the liquid/air interface and thus, it confers protection of the alveoli from collapsing. The surface-active component of LS is dipalmitoyl-phosphatidylcholine, while anionic phospholipids such as phosphatidylinositol (PtdIns) and primarily phosphatidylglycerol are involved in the stabilization of the LS monolayer.
View Article and Find Full Text PDFA variety of lower eukaryotes and certain mammalian cells are known to constitutively secrete lysosomal hydrolases. Recent studies in Tetrahymena have shown that phosphatidylinositol 3-phosphate regulates the proper secretion of lysosomal enzymes at the level of phagolysosome formation. We extend these findings by studying the secretion-deficient strain MS-1 of Tetrahymena thermophila, which possess phosphatidylinositol levels similar to wild type.
View Article and Find Full Text PDFLipid modifying enzymes play a key role in the development of cold stress tolerance in cold-resistant plants such as cereals. However, little is known about the role of the endogenous enzymes in cold-sensitive species such as cotton. Delta 12 fatty acid desaturases (FAD2), known to participate in adaptation to low temperatures through acyl chain modifications were used in gene expression studies in order to identify parameters of plant response to low temperatures.
View Article and Find Full Text PDFThe role of phosphoinositide-specific phospholipase C (PI-PLC) signaling in the macrotubule-dependent protoplast volume regulation in plasmolyzed root cells of Triticum turgidum was investigated. At the onset of hyperosmotic stress, PI-PLC activation was documented. Inhibition of PI-PLC activity by U73122 blocked tubulin macrotubule formation in plasmolyzed cells and their protoplast volume regulatory mechanism.
View Article and Find Full Text PDFTumour necrosis factor alpha (TNFalpha) induces platelet-activating factor (PAF) synthesis in many inflammatory cells. Here, we investigate the possibility that TNFalpha stimulates PAF synthesis in rat adipocytes and preadipocytes and that phosphoinositide 3-kinase (PI3K) and extracellular signal-regulated kinase 1/2 (ERK1/2) are implicated in this process. Primary cultures were incubated with [3H]lyso-PAF and stimulated by TNFalpha in the presence or absence of wortmannin.
View Article and Find Full Text PDFPhosphatidylinositol 3-phosphate, PtdIns3P, is a phosphoinositide which is implicated in regulating membrane trafficking in both mammalian and yeast cells. It also serves as a precursor for the synthesis of phosphatidylinositol 3,5-bisphosphate, PtdIns3,5P2, a phosphoinositide, the exact functions of which remain unknown. In this report, we show that these two phosphoinositides are constitutive lipid components of the ciliate Tetrahymena.
View Article and Find Full Text PDFArabidopsis phosphatidylinositol phosphate (PtdInsP) kinase 10 (AtPIPK10; At4g01190) is shown to be a functional enzyme of the subfamily A, type I AtPtdInsP kinases. It is biochemically distinct from AtPIPK1 (At1g21980), the only other previously characterized AtPtdInsP kinase which is of the B subfamily. AtPIPK10 has the same K(m), but a 10-fold lower V(max) than AtPIPK1 and it is insensitive to phosphatidic acid.
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