scholarly journals Selectivity of mTOR-Phosphatidic Acid Interactions Is Driven by Acyl Chain Structure and Cholesterol

Cells ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 119
Author(s):  
Jolanta Żelasko ◽  
Aleksander Czogalla
Keyword(s):  
Phosphatidic Acid ◽  
Lipid Membrane ◽  
Specific Binding ◽  
Acyl Chain ◽  
Chain Structure ◽  
Fine Tuning ◽  
Signaling Cascades ◽  
Cell Physiology ◽  
Acyl Chain Length ◽  
Acyl Chains

The need to gain insights into the molecular details of peripheral membrane proteins’ specificity towards phosphatidic acid (PA) is undeniable. The variety of PA species classified in terms of acyl chain length and saturation translates into a complicated, enigmatic network of functional effects that exert a critical influence on cell physiology. As a consequence, numerous studies on the importance of phosphatidic acid in human diseases have been conducted in recent years. One of the key proteins in this context is mTOR, considered to be the most important cellular sensor of essential nutrients while regulating cell proliferation, and which also appears to require PA to build stable and active complexes. Here, we investigated the specific recognition of three physiologically important PA species by the mTOR FRB domain in the presence or absence of cholesterol in targeted membranes. Using a broad range of methods based on model lipid membrane systems, we elucidated how the length and saturation of PA acyl chains influence specific binding of the mTOR FRB domain to the membrane. We also discovered that cholesterol exerts a strong modulatory effect on PA-FRB recognition. Our data provide insight into the molecular details of some physiological effects reported previously and reveal novel mechanisms of fine-tuning the signaling cascades dependent on PA.

scholarly journals Acyl-chain selectivity of the 85 kDa phospholipase A2 and of the release process in intact macrophages

1994 ◽  
Vol 301 (2) ◽  
pp. 455-458 ◽  
Author(s):  
R Sundler ◽  
D Winstedt ◽  
J Wijkander
Keyword(s):  
Phospholipase A2 ◽  
Acyl Chain ◽  
Calcium Ionophore ◽  
Release Process ◽  
In Vitro System ◽  
Acyl Chain Length ◽  
Mouse Macrophages ◽  
J774 Cells ◽  
Acyl Chains

The selectivity of the intracellular 85 kDa phospholipase A2 (PLA2-85) towards fatty acids closely related to arachidonic acid has been investigated, using purified PLA2-85 from J774 cells and mixed phospholipids, dually acyl-chain-labelled in the sn-2 position. In parallel experiments, we assessed the acyl-chain selectivity of the release process in intact, dually labelled, peritoneal mouse macrophages responding to either calcium ionophore or zymosan beads in the presence of indomethacin and BSA. The results obtained in the two systems were very similar, which supports previous evidence that PLA2-85 is responsible for stimulus-induced release of eicosanoid precursor in mouse macrophages. In the in vitro system, PLA2-85 was found to exhibit a moderate selectivity towards C20 acyl chains differing in double-bond structure, while the sensitivity to acyl-chain length was more pronounced. Together with previous data, these results demonstrate a striking preference for C20 over either C18 or C22 unsaturated acyl chains.

scholarly journals Shortening the Lipid A Acyl Chains of Bordetella pertussis Enables Depletion of Lipopolysaccharide Endotoxic Activity

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 594
Author(s):  
Jesús Arenas ◽  
Elder Pupo ◽  
Coen Phielix ◽  
Dionne David ◽  
Afshin Zariri ◽  
...  
Keyword(s):  
Bordetella Pertussis ◽  
Lipid A ◽  
Whooping Cough ◽  
Acyl Chain ◽  
In Vitro Assays ◽  
Whole Cell ◽  
Whole Cells ◽  
Acyl Chain Length ◽  
Acyl Chains

Whooping cough, or pertussis, is an acute respiratory infectious disease caused by the Gram-negative bacterium Bordetella pertussis. Whole-cell vaccines, which were introduced in the fifties of the previous century and proved to be effective, showed considerable reactogenicity and were replaced by subunit vaccines around the turn of the century. However, there is a considerable increase in the number of cases in industrialized countries. A possible strategy to improve vaccine-induced protection is the development of new, non-toxic, whole-cell pertussis vaccines. The reactogenicity of whole-cell pertussis vaccines is, to a large extent, derived from the lipid A moiety of the lipopolysaccharides (LPS) of the bacteria. Here, we engineered B. pertussis strains with altered lipid A structures by expressing genes for the acyltransferases LpxA, LpxD, and LpxL from other bacteria resulting in altered acyl-chain length at various positions. Whole cells and extracted LPS from the strains with shorter acyl chains showed reduced or no activation of the human Toll-like receptor 4 in HEK-Blue reporter cells, whilst a longer acyl chain increased activation. Pyrogenicity studies in rabbits confirmed the in vitro assays. These findings pave the way for the development of a new generation of whole-cell pertussis vaccines with acceptable side effects.

scholarly journals The elongation of exogenous fatty acids and the control of phospholipid acyl chain length in Micrococcus cryophilus

1980 ◽  
Vol 188 (3) ◽  
pp. 585-592 ◽  
Author(s):  
S P Sandercock ◽  
N J Russell
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Chain Length ◽  
De Novo ◽  
Acyl Chain ◽  
Psychrophilic Bacterium ◽  
Fatty Acid Elongation ◽  
Acyl Chain Length ◽  
Acyl Chains ◽  
Phospholipid Acyl Chain

The synthesis of fatty acids de novo from acetate and the elongation of exogenous satuated fatty acids (C12-C18) by the psychrophilic bacterium Micrococcus cryophilus (A.T.C.C. 15174) grown at 1 or 20 degrees C was investigated. M. cryophilus normally contains only C16 and C18 acyl chains in its phospholipids, and the C18/C16 ratio is altered by changes in growth temperature. The bacterium was shown to regulate strictly its phospholipid acyl chain length and to be capable of directly elongating myristate and palmitate, and possibly laurate, to a mixture of C16 and C18 acyl chains. Retroconversion of stearate into palmitate also occurred. Fatty acid elongation could be distinguished from fatty acid synthesis de novo by the greater sensitivity of fatty acid elongation to inhibition by NaAsO2 under conditions when the supply of ATP and reduced nicotinamide nucleotides was not limiting. It is suggested that phospholipid acyl chain length may be controlled by a membrane-bound elongase enzyme, which interconverts C16 and C18 fatty acids via a C14 intermediate; the activity of the enzyme could be regulated by membrane lipid fluidity.

scholarly journals The acyltransferase LYCAT controls specific phosphoinositides and related membrane traffic

2017 ◽  
Vol 28 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Leslie N. Bone ◽  
Roya M. Dayam ◽  
Minhyoung Lee ◽  
Nozomu Kono ◽  
Gregory D. Fairn ◽  
...  
Keyword(s):  
Acyl Chain ◽  
Membrane Traffic ◽  
Cell Physiology ◽  
Phosphatidylinositol Synthase ◽  
Lipid Kinases ◽  
Acyl Chains ◽  
And Function ◽  
Phosphatidylinositol 4 ◽  
Phosphatidylinositol 3

Phosphoinositides (PIPs) are key regulators of membrane traffic and signaling. The interconversion of PIPs by lipid kinases and phosphatases regulates their functionality. Phosphatidylinositol (PI) and PIPs have a unique enrichment of 1-stearoyl-2-arachidonyl acyl species; however, the regulation and function of this specific acyl profile remains poorly understood. We examined the role of the PI acyltransferase LYCAT in control of PIPs and PIP-dependent membrane traffic. LYCAT silencing selectively perturbed the levels and localization of phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] and phosphatidylinositol-3-phosphate and the membrane traffic dependent on these specific PIPs but was without effect on phosphatidylinositol-4-phosphate or biosynthetic membrane traffic. The acyl profile of PI(4,5)P2 was selectively altered in LYCAT-deficient cells, whereas LYCAT localized with phosphatidylinositol synthase. We propose that LYCAT remodels the acyl chains of PI, which is then channeled into PI(4,5)P2. Our observations suggest that the PIP acyl chain profile may exert broad control of cell physiology.

Effect of Alkyl Chain Length on Molecular Heat Transfer Characteristics in Lipid Bilayers

2011 ◽  
Author(s):  
Takeo Nakano ◽  
Gota Kikugawa ◽  
Taku Ohara
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Lipid Bilayers ◽  
Chain Length ◽  
Phosphatidyl Choline ◽  
Acyl Chain ◽  
Nonequilibrium Molecular Dynamics ◽  
Acyl Chain Length ◽  
Acyl Chains ◽  
Dynamics Simulations

Nonequilibrium molecular dynamics simulations are carried out on single component lipid bilayers with ambient water in order to investigate the effect of acyl chain length on heat transport characteristics along and across the membranes. In this study, dipalmitoyl-phosphatidyl-choline (DPPC), dilauroyl-phosphatidyl-choline (DLPC), and stearoyl-myristoyl-phosphatidyl-choline (SMPC) which has two acyl chains of both sixteen C atoms, both twelve C atoms, and eighteen and fourteen C atoms, respectively, were used as lipid molecules. In the direction along the membranes, thermal conductivity corresponds with that of each membrane. On the other hand, in the direction across membrane, the highest thermal resistance exists at the center of lipid bilayer where lipid acyl chains face each other. However, asymmetric chain length reduces thermal resistance at the interface between lipid monolayers. Therefore, thermal conductivity across the membrane which consists of asymmetric chain length is higher than those which consist of symmetric chain length.

scholarly journals Acyl-chain saturation regulates the order of phosphatidylinositol 4,5-bisphosphate nanodomains

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Luís Borges-Araújo ◽  
Marco M. Domingues ◽  
Alexander Fedorov ◽  
Nuno C. Santos ◽  
Manuel N. Melo ◽  
...  
Keyword(s):  
Negative Curvature ◽  
Acyl Chain ◽  
Critical Role ◽  
Chain Structure ◽  
Membrane Remodeling ◽  
Biophysical Properties ◽  
Chain Composition ◽  
Acyl Chain Composition ◽  
Acyl Chains ◽  
The Impact

AbstractPhosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) plays a critical role in the regulation of various plasma membrane processes and signaling pathways in eukaryotes. A significant amount of cellular resources are spent on maintaining the dominant 1-stearoyl-2-arachidonyl PI(4,5)P2 acyl-chain composition, while less abundant and more saturated species become more prevalent in response to specific stimuli, stress or aging. Here, we report the impact of acyl-chain structure on the biophysical properties of cation-induced PI(4,5)P2 nanodomains. PI(4,5)P2 species with increasing levels of acyl-chain saturation cluster in progressively more ordered nanodomains, culminating in the formation of gel-like nanodomains for fully saturated species. The formation of these gel-like domains was largely abrogated in the presence of 1-stearoyl-2-arachidonyl PI(4,5)P2. This is, to the best of our knowledge, the first report of the impact of PI(4,5)P2 acyl-chain composition on cation-dependent nanodomain ordering, and provides important clues to the motives behind the enrichment of PI(4,5)P2 with polyunsaturated acyl-chains. We also show how Ca2+-induced PI(4,5)P2 nanodomains are able to generate local negative curvature, a phenomenon likely to play a role in membrane remodeling events.

scholarly journals Mitogenic action of lysophosphatidic acid and phosphatidic acid on fibroblasts. Dependence on acyl-chain length and inhibition by suramin

1992 ◽  
Vol 281 (1) ◽  
pp. 163-169 ◽  
Author(s):  
E J van Corven ◽  
A van Rijswijk ◽  
K Jalink ◽  
R L van der Bend ◽  
W J van Blitterswijk ◽  
...  
Keyword(s):  
Growth Factor ◽  
Phosphatidic Acid ◽  
Dna Synthesis ◽  
Chain Length ◽  
Lysophosphatidic Acid ◽  
Rank Order ◽  
Acyl Chain ◽  
Dependent Manner ◽  
Acyl Chain Length ◽  
Mitogenic Action

Lysophosphatidic acid (LPA) is a naturally occurring phospholipid with growth-factor-like activities [van Corven, Groenink, Jalink, Eichholtz & Moolenaar (1989) Cell 45, 45-54]. We have examined various structural analogues of LPA for their ability to stimulate DNA synthesis in quiescent fibroblasts. When the acyl-chain length is varied, the rank order of mitogenic potency is: 1-oleoyl LPA congruent to 1-palmitoyl LPA greater than 1-myristoyl LPA greater than 1-lauroyl LPA greater than 1-decanoyl LPA; the last compound shows almost no activity over the concentration range tested (1-100 microM). An ether-linked LPA (1-O-hexadecylglycerol 3-phosphate) has much decreased mitogenic activity as compared with the ester-linked analogue at concentrations less than 25 microM, and becomes cytotoxic at higher concentrations. Hexadecylphosphate, which lacks a glycerol backbone, has negligible activity. On a molar basis, diacyl phosphatidic acid (PA) is about equally potent as the corresponding LPA analogue, showing similar acyl-chain-length dependence; the data argue against the possibility that the mitogenic action of PA is due to contaminating traces of LPA. Although the short-chain analogues of LPA and PA fail to antagonize the action of long-chain (L)PAs, the polyanionic drug suramin inhibits LPA- and PA-induced, DNA synthesis in a reversible and dose-dependent manner, at concentrations [IC50 (concn. giving 50% inhibition) approximately 70 microM] that do not affect epidermal-growth-factor-induced DNA synthesis. Suramin appears to act in the early G0/G1 phase of the cell cycle, blocking immediate responses to LPA such as phosphoinositide hydrolysis. We conclude that both LPA and PA can function as growth-promoting phospholipids, with the fatty acid chain length being a major determinant of mitogenic potency.

scholarly journals Acyl Chain Specificity of Marine Streptomyces klenkii PhosPholipase D and Its Application in Enzymatic Preparation of Phosphatidylserine

2021 ◽  
Vol 22 (19) ◽  
pp. 10580
Author(s):  
Rongkang Hu ◽  
Ruiguo Cui ◽  
Dongming Lan ◽  
Fanghua Wang ◽  
Yonghua Wang
Keyword(s):  
Phospholipase D ◽  
Substrate Binding ◽  
Acyl Chain ◽  
Catalytic Efficiency ◽  
Head Group ◽  
Acyl Chain Length ◽  
Hydrogen Bond Interactions ◽  
Binding Pockets ◽  
Acyl Chains ◽  
Marine Streptomyces

Mining of phospholipase D (PLD) with altered acyl group recognition except its head group specificity is also useful in terms of specific acyl size phospholipid production and as diagnostic reagents for quantifying specific phospholipid species. Microbial PLDs from Actinomycetes, especially Streptomyces, best fit this process requirements. In the present studies, a new PLD from marine Streptomyces klenkii (SkPLD) was purified and biochemically characterized. The optimal reaction temperature and pH of SkPLD were determined to be 60 °C and 8.0, respectively. Kinetic analysis showed that SkPLD had the relatively high catalytic efficiency toward phosphatidylcholines (PCs) with medium acyl chain length, especially 12:0/12:0-PC (67.13 S−1 mM−1), but lower catalytic efficiency toward PCs with long acyl chain (>16 fatty acids). Molecular docking results indicated that the different catalytic efficiency was related to the increased steric hindrance of long acyl-chains in the substrate-binding pockets and differences in hydrogen-bond interactions between the acyl chains and substrate-binding pockets. The enzyme displayed suitable transphosphatidylation activity and the reaction process showed 26.18% yield with L-serine and soybean PC as substrates. Present study not only enriched the PLD enzyme library but also provide guidance for the further mining of PLDs with special phospholipids recognition properties.

scholarly journals Different rates of flux through the biosynthetic pathway for long-chain versus very-long-chain sphingolipids

2020 ◽  
Vol 61 (10) ◽  
pp. 1341-1346
Author(s):  
Iris D. Zelnik ◽  
Giora Volpert ◽  
Leena E. Viiri ◽  
Dimple Kauhanen ◽  
Tamar Arazi ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Chain Length ◽  
Biosynthetic Pathway ◽  
Acyl Chain ◽  
Degree Of Saturation ◽  
Disease States ◽  
Acyl Chain Length ◽  
Long Chain Base ◽  
Acyl Chains ◽  
Long Chain

The backbone of all sphingolipids (SLs) is a sphingoid long-chain base (LCB) to which a fatty acid is N-acylated. Considerable variability exists in the chain length and degree of saturation of both of these hydrophobic chains, and recent work has implicated ceramides with different LCBs and N-acyl chains in distinct biological processes; moreover, they may play different roles in disease states and possibly even act as prognostic markers. We now demonstrate that the half-life, or turnover rate, of ceramides containing diverse N-acyl chains is different. By means of a pulse-labeling protocol using stable-isotope, deuterated free fatty acids, and following their incorporation into ceramide and downstream SLs, we show that very-long-chain (VLC) ceramides containing C24:0 or C24:1 fatty acids turn over much more rapidly than long-chain (LC) ceramides containing C16:0 or C18:0 fatty acids due to the more rapid metabolism of the former into VLC sphingomyelin and VLC hexosylceramide. In contrast, d16:1 and d18:1 ceramides show similar rates of turnover, indicating that the length of the sphingoid LCB does not influence the flux of ceramides through the biosynthetic pathway. Together, these data demonstrate that the N-acyl chain length of SLs may not only affect membrane biophysical properties but also influence the rate of metabolism of SLs so as to regulate their levels and perhaps their biological functions.

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