Membrane fusion mediated by ricin and viscumin

Pohl, Peter; Antonenko, Yura N; Evtodienko, Veronika Yu.; Pohl, Elena E.; Saparov, Sapar M.; Агапов, И. И.; Tonevitsky, Alexander G.

doi:10.1016/s0005-2736(98)00024-8

Cited by 29 publications

(23 citation statements)

References 30 publications

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“…These findings raised the question of the presence of another mechanism by which ricin could penetrate the cellular membrane and which was not limited to the lectin activity of RTB. More recent studies also showed that RTB [15] and ricin [16] could induce membrane fusion on liposomes. The ability of ricin and RTB to interact with lipids is Abbreviations used : RSA 60 , 60 kDa Ricinus sanguineus ricin ; RCA 60 , 60 kDa Ricinus communis ricin ; RTA, ricin toxin A-chain ; RTB, ricin toxin Bchain ; ATCL6B, acid-treated cross-linked sepharose 6B ; pNPC 2 , p -nitrophenyl acetate ; pNPC 4 , pNP butyrate ; pNPC 6 , pNP hexanoate ; pNPC 8 , pNP octanoate ; pNPC 10 , pNP decanoate ; pNPC 12 , pNP dodecanoate ; DTNB, 5,5h-dithiobis-(2-nitrobenzoic acid) ; BAL-TC 4 , 2,3-dimercapto-1-propanol tributyrate ; DC 10 , dicaprin ; E 600 , diethyl p -nitrophenylphosphate ; τ, lag time.…”

Section: Introductionmentioning

confidence: 92%

Lipolytic activity of ricin from Ricinus sanguineus and Ricinus communis on neutral lipids

LOMBARD

Helmy

Piéroni

2001

Biochemical Journal

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The present study was carried out with a view of determining ricin lipolytic activity on neutral lipids in emulsion and in a membrane-like model. Using 2,3-dimercapto-1-propanol tributyrate (BAL-TC % ) as substrate, the lipolytic activity of ricin was found to be proportional to ricin and substrate concentrations, with an apparent K m (K m,app ) of 2.4 mM, a k cat of 200 min −" and a specific activity of 1.0 unit\mg of protein. This work was extended to p-nitrophenyl ( pNP) fatty acid esters containing two to twelve carbon atoms. Maximum lipolytic activity was registered on pNP decanoate ( pNPC "! ), with a K m,app of 3.5 mM, a k cat of 173 min −" and a specific activity of 3.5 units\mg of protein.Ricin lipolytic activity is pH and galactose dependent, with a maximum at pH 7.0 in the presence of 0.2 M galactose. Using the monolayer technique with dicaprin as substrate, ricin showed a lipolytic activity proportional to the ricin concentration at 20 mN\m, which is dependent on the surface pressure of the lipid monolayer and is detectable up to 30 mN\m, a surface pressure that is of the same order of magnitude as that of natural cell

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Section: Introductionmentioning

confidence: 92%

Lipolytic activity of ricin from Ricinus sanguineus and Ricinus communis on neutral lipids

LOMBARD

Helmy

Piéroni

2001

Biochemical Journal

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“…This assay has been used continuously in a variety of labs for fusion/reconstruction studies (48)(49)(50)(51)(54)(55)(56)(57)(58)(59)(60). Liposome fusion to planar bilayers was measured using standard electrophysiological equipment (Bilayer Clamp Amplifier model BC-535 or BC-525C, Warner Instruments, Hamden CT).…”

Section: Fusion Assaymentioning

confidence: 99%

“…This and related methods model exocytosis in a protein-free system by using an osmotic gradient to fuse liposomes to a planar lipid bilayer (BLM) (43)(44)(45)(46). A variation of this, the nystatin/ergosterol (nys/erg) fusion assay, was originally developed in our lab (47) to aid in the reconstitution and study of a chloride channel, but now has been used as a model system to study protein (48,49) and lipid (50,51) factors that alter vesicle fusion. With such model systems, it may be possible to bridge the gap between molecular models and cellular studies of how alcohol modulates membrane function during neuronal synaptic transmission.…”

Section: Introductionmentioning

confidence: 99%

Drunken Membranes: Short-Chain Alcohols Alter Fusion of Liposomes to Planar Lipid Bilayers

Paxman

Hunt

Hallan

et al. 2017

Biophysical Journal

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Although the effects of ethanol on protein receptors and lipid membranes have been studied extensively, ethanol's effect on vesicles fusing to lipid bilayers is not known. To determine the effect of alcohols on fusion rates, we utilized the nystatin/ergosterol fusion assay to measure fusion of liposomes to a planar lipid bilayer (BLM). The addition of ethanol excited fusion when applied on the cis (vesicle) side, and inhibited fusion on the trans side. Other short-chain alcohols followed a similar pattern. In general, the inhibitory effect of alcohols (trans) occurs at lower doses than the excitatory (cis) effect, with a decrease of 29% in fusion rates at the legal driving limit of 0.08% (w/v) ethanol (IC 50 ¼ 0.2% v/v, 34 mM). Similar inhibitory effects were observed with methanol, propanol, and butanol, with ethanol being the most potent. Significant variability was observed with different alcohols when applied to the cis side. Ethanol and propanol enhanced fusion, butanol also enhanced fusion but was less potent, and low doses of methanol mildly inhibited fusion. The inhibition by trans addition of alcohols implies that they alter the planar membrane structure and thereby increase the activation energy required for fusion, likely through an increase in membrane fluidity. The cis data are likely a combination of the above effect and a proportionally greater lowering of the vesicle lysis tension and hydration repulsive pressure that combine to enhance fusion. Alternate hypotheses are also discussed. The inhibitory effect of ethanol on liposome-membrane fusion is large enough to provide a possible biophysical explanation of compromised neuronal behavior.

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“…Precisely how type I RIPs which do not have a cell-binding chain inhibit fungi, i.e., how are they internalized, is not known. Both type I and type 2 RIPs show broad activity against a number of plant and human pathogenic fungi as well as toxicity against mammalian cells (some type 2 RIPs are highly toxic to animals, likely because of the presence of the cell-binding B chain) (132,142,146).…”

Section: Fungal Cell Wall Structurementioning

confidence: 99%