Enzyme Catalysis Enhances Lateral Lipid Motility and Directional Particle Transport on Membranes

The dynamic interplay between the composition of lipid membranes and the behavior of membrane-bound enzymes is critical to the understanding of cellular function and viability, and the design of membrane-based biosensing platforms. While there is a significant body of knowledge on how lipid composition and dynamics affect membrane-bound enzymes, little is known about how enzyme catalysis influences the motility and lateral transport in lipid membranes. Using enzymes-attached lipids in supported bilayers (SLB), we show catalysis-induced enhanced lateral diffusion of lipids in the bilayer. Enhancing the membrane viscosity by increasing the cholesterol content in the bilayer suppresses the overall diffusion but not the relative diffusion enhancement of the enzyme-attached lipids. We also provide direct evidence of catalysis-induced membrane fluctuations leading to the enhanced diffusion of passive tracers resting on the SLB. Additionally, by using active enzyme patches, we demonstrate the directional transport of tracers on SLBs. These are first steps in understanding diffusion and transport in lipid membranes due to active, out-of-equilibrium processes that are the hallmark of living systems. In general, our study demonstrates how active enzymes can be used to control diffusion and transport in confined 2-D environments.

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The Interaction of Polyene Antibiotics with Thin Lipid Membranes

The Journal of General Physiology ◽

10.1085/jgp.52.2.300 ◽

1968 ◽

Vol 52 (2) ◽

pp. 300-325 ◽

Cited By ~ 90

Author(s):

Thomas E. Andreoli ◽

Marcia Monahan

Keyword(s):

Amphotericin B ◽

Lipid Membranes ◽

Sheep Erythrocyte ◽

Cholesterol Content ◽

Transference Numbers ◽

Ionic Selectivity ◽

Antibiotic Concentration ◽

Polyene Antibiotics ◽

Cyclic Polyene ◽

Membrane Bound

Optically black, thin lipid membranes prepared from sheep erythrocyte lipids have a high dc resistance (Rm ≅ 108 ohm-cm2) when the bathing solutions contain NaCl or KCl. The ionic transference numbers (Ti) indicate that these membranes are cation-selective (TNa ≅ 0.85; TCl ≅ 0.15). These electrical properties are independent of the cholesterol content of the lipid solutions from which the membranes are formed. Nystatin, and probably amphotericin B, are cyclic polyene antibiotics containing ≈36 ring atoms and a free amino and carboxyl group. When the lipid solutions used to form membranes contained equimolar amounts of cholesterol and phospholipid, these antibiotics reduced Rm to ≈102 ohm-cm2; concomitantly, TCl became ≅0.92. The slope of the line relating log Rm and log antibiotic concentration was ≅4.5. Neither nystatin (2 x 10-5 M) nor amphotericin B (2 x 10-7 M) had any effect on membrane stability. The antibiotics had no effect on Rm or membrane permselectivity when the lipids used to form membranes were cholesterol-depleted. Filipin (10-5 M), an uncharged polyene with 28 ring atoms, produced striking membrane instability, but did not affect Rm or membrane ionic selectivity. These data suggest that amphotericin B or nystatin may interact with membrane-bound sterols to produce multimolecular complexes which greatly enhance the permeability of such membranes for anions (Cl-, acetate), and, to a lesser degree, cations (Na+, K+, Li+).

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The Cellular and Chemical Biology of Endocytic Trafficking and Intracellular Delivery—The GL–Lect Hypothesis

Molecules ◽

10.3390/molecules26113299 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3299

Author(s):

Ludger Johannes

Keyword(s):

Lipid Membranes ◽

Tumor Targeting ◽

Chemical Biology ◽

Reverse Genetics ◽

Lateral Diffusion ◽

Intracellular Delivery ◽

Membrane Bound ◽

Delivery Strategies ◽

Synthetic Approaches ◽

Biology Research

Lipid membranes are common to all forms of life. While being stable barriers that delimitate the cell as the fundamental organismal unit, biological membranes are highly dynamic by allowing for lateral diffusion, transbilayer passage via selective channels, and in eukaryotic cells for endocytic uptake through the formation of membrane bound vesicular or tubular carriers. Two of the most abundant fundamental fabrics of membranes—lipids and complex sugars—are produced through elaborate chains of biosynthetic enzymes, which makes it difficult to study them by conventional reverse genetics. This review illustrates how organic synthesis provides access to uncharted areas of membrane glycobiology research and its application to biomedicine. For this Special Issue on Chemical Biology Research in France, focus will be placed on synthetic approaches (i) to study endocytic functions of glycosylated proteins and lipids according to the GlycoLipid–Lectin (GL–Lect) hypothesis, notably that of Shiga toxin; (ii) to mechanistically dissect its endocytosis and intracellular trafficking with small molecule; and (iii) to devise intracellular delivery strategies for immunotherapy and tumor targeting. It will be pointed out how the chemical biologist’s view on lipids, sugars, and proteins synergizes with biophysics and modeling to “look” into the membrane for atomistic scale insights on molecular rearrangements that drive the biogenesis of endocytic carriers in processes of clathrin-independent endocytosis.

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The effect of membrane cholesterol depletion upon erythrocyte membrane-bound enzymes

Canadian Journal of Biochemistry ◽

10.1139/o79-147 ◽

1979 ◽

Vol 57 (9) ◽

pp. 1144-1152 ◽

Cited By ~ 13

Author(s):

J. D. Vickers ◽

M. P. Rathbone

Keyword(s):

Protein Kinase ◽

Enzyme Activities ◽

Membrane Lipids ◽

Cholesterol Content ◽

Erythrocyte Membranes ◽

Membrane Cholesterol ◽

Cholesterol Depletion ◽

Membrane Bound ◽

Membrane Bound Enzymes

The cholesterol content of normal human erythrocyte membranes (ghosts) was reduced by incubation of the ghosts with phosphatidylcholine (PC) liposomes for 4 h at 37 °C. As controls, ghosts were stored at 4 °C, incubated alone or incubated with PC liposomes saturated with cholesterol; none of these treatments altered membrane cholesterol content. The activities of three membrane-bound enzymes, spectrin kinase, band-3 protein kinase, and phospholipid kinase were reduced in cholesterol-depleted ghosts compared with control ghosts (p < 0.02, p < 0.05, and p < 0.01, respectively). Reductions of the protein kinase activities ranged from 5 to 30% and were apparently related to the extent of the reduction of ghost cholesterol content. The reduction of phospholipid kinase activity was greater (30–60%) and showed no correlation with the extent of reduction of ghost cholesterol content. In contrast to the kinase activities, the activity of a fourth enzyme, NADH: cytochrome c oxidoreductase, increased in response to membrane cholesterol depletion. The relationship between the increase in oxidoreductase activity and cholesterol depletion was best described as linear (r = 0.76).The data demonstrate that these enzyme activities are affected by membrane cholesterol content. Since the alterations in the enzyme activities caused by the artificial alterations of membrane cholesterol content were comparable with those observed in vivo in various pathological conditions, we suggest that the observed changes may be due to mechanisms whereby membrane lipids influence membrane enzyme activities in vivo.

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Alterations in the Activities of Rabbit Erythrocyte Membrane-Bound Enzymes Induced by Cholesterol Enrichment and Depletion Procedures

Zeitschrift für Naturforschung C ◽

10.1515/znc-1986-0310 ◽

1986 ◽

Vol 41 (3) ◽

pp. 301-309 ◽

Cited By ~ 3

Author(s):

Elli Kamber ◽

Liudmila Kopeikina-Tsiboukidou

Keyword(s):

Membrane Surface ◽

Cholesterol Content ◽

Inhibitory Effect ◽

Erythrocyte Membranes ◽

Molar Ratio ◽

Inhibition Mechanism ◽

Intact Cells ◽

Egg Lecithin ◽

Membrane Bound ◽

Membrane Bound Enzymes

The effect of cholesterol enrichment and depletion of rabbit erythrocytes on the activities of membrane-bound enzymes, namely (Na+ ,K+)-stimulated ATPase. NAD+ ase and acetylcholinesterase was examined. The cholesterol content of erythrocyte membranes has been modified by incubation of intact cells with sonicated egg lecithin/cholesterol vesicles (cholesterol/phospholipid molar ratio approx. 2) and with egg lecithin vesicles for time intervals up to 10 hours. The cholesterol/phospholipid molar ratio (CH /PL) of untreated rabbit red blood cell membranes was 0 .92-0.94. Linear increase (up to CH/PL molar ratio 1.72-1.9) or decrease (up to CH/PL molar ratio 0.27 - 0.43) in cholesterol content of erythrocyte membranes was observed over the 10 hours of incubation with egg lecithin/cholesterol and egg lecithin liposomes respectively. Fusion of liposom es to the m em brane or their attachment to the membrane surface was not a significant factor in the alteration of CH/PL ratio. (N+,K+ )-stimulated ATPase, NAD+ ase and acetylcholinesterase activities were measured as a function of membrane cholesterol. The specific activities of all three enzymes were progressively decreased with increase in cholesterol content. Partial reversibility of the inhibitory effect of cholesterol was demonstrated by measurements on cells depleted again after cholesterol enrichment. This was confirmed by the fact that a lowering in cholesterol content evoked an analogous activation of enzymes. The possible implications of physicochemical modifications of bulk and annular lipids of membrane-bound enzymes in the inhibition mechanism are discussed.

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Some Aspects of the Polyhexamethyleneguanidine Salts Effect on Cell Cultures

Agricultural science and practice ◽

10.15407/agrisp1.01.062 ◽

2014 ◽

Vol 1 (1) ◽

pp. 62-67 ◽

Cited By ~ 2

Author(s):

M. Mandygra ◽

A. Lysytsia

Keyword(s):

Proliferative Activity ◽

Cell Monolayer ◽

Eukaryotic Cell ◽

Culture Methods ◽

Cellular Processes ◽

Negative Effect ◽

Membrane Bound ◽

Membrane Bound Enzymes ◽

Anion Type ◽

Cell Culture Methods

Aim. To investigate the effect of polyhexamethyleneguanidine (PHMG) to eukaryotic cell culture. Methods. The passaged bovine tracheal cells culture (TCC) and primary culture of chicken embryo fi broblasts (FCE) were used in the experiments. TCC and FCE monolayers were treated with aqueous solutions of PHMG chloride or succinate. The method of PHMG polycation adsorption to the cells’ plasma membrane together with microscopy were applied. Results. The dependence of PHMG effect on the eukaryotic cells on the agent concentration, duration of exposure and the anion type has been fi xed. The PHMG concentration of 10 –5 per cent (0.1 μg/ml) never causes degradation of the previously formed cell monolayer, while the higher concentrations damage it. The conditions of the PHMG chloride and succinate’s negative effect on cell proliferation and inhibition of monolayer formation were determined. The hypothesis that under certain conditions PHMG stimulates the proliferative activity of the cells has been confi rmed. Stimulation may be associated with non-specifi c stress adaptation of cells. In this case, it is due to modifi cations of the cell membrane after PHMG adsorption to it. Conclusions. PHMG polycation binds with the membrane’s phosphoglycerides fi rmly and irreversibly. A portion of the lipids are removed from participation in the normal cellular processes at that. At the same time, the synthesis of new lipids and membrane-bound enzymes is probably accelerated. The phospholip ids’ neogenesis acceleration can stimulate mitosis under certain conditions. The obtained results can be used in the biotechnologies.

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