Probability of alamethicin conductance states varies with nonlamellar tendency of bilayer phospholipids

Keller, Sarah L.; Bezrukov, Sergey M.; Grüner, Sol M.; Täte, Mark W.; Vodyanoy, Igor; Parsegian, V. Adrian

doi:10.1016/s0006-3495(93)81040-3

Cited by 256 publications

(257 citation statements)

References 27 publications

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“…Because it is quite likely that in fact the more stressed lipids will aggregate around the CCT, we must accept the approximate nature of the model. Reliable experimental values of c 0 , , and A are known for DOPC and DOPE (25,26,32,34) (Table 1), and we are therefore able to fit S (x) for mixtures of these lipids (Fig. 2).…”

Section: Discussion and Analysismentioning

confidence: 84%

Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress

Attard

Templer

Smith

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

243

222

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Section: Discussion and Analysismentioning

confidence: 84%

Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress

Attard

Templer

Smith

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

243

222

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“…Figure 4 shows calcein release in 1:1 mixtures of DOPA with the lipids Me-DOPE or Me 2 -DOPE, whose structures are shown in Table 1; data again fit well to a single-exponential process. The spontaneous curvature for Me-DOPE is the same as that for a 1:2 mixture of DOPC and DOPE (12), and that for Me 2 -DOPE is predicted to be the same as for a 2:1 mixture of DOPC and DOPE (31). When the rates and amplitudes of calcein release in the presence of Me-DOPE and Me 2 -DOPE are plotted as a function of the number of methyl groups, they do not fit on the curves established by the DOPC/DOPE data ( Figure 3).…”

Section: Do Effects Of Zwitterionic Lipids On Mscl Function Correlatementioning

confidence: 87%

Importance of Direct Interactions with Lipids for the Function of the Mechanosensitive Channel MscL

2008

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We have studied the effects of lipid structure on the function of the mechanosensitive channel of large conductance (MscL) from Escherichia coli to determine whether effects follow from direct interaction between the lipids and protein or whether they follow indirectly from changes in the curvature stress in the membrane. The G22C mutant of MscL was reconstituted into sealed vesicles containing the fluorescent molecule calcein, and the release of calcein from the vesicles was measured following opening of the channel by reaction with [2-(triethylammonium)ethyl] methanethiosulfonate (MTSET), which introduces five positive charges into the region of the pore constriction. The presence of anionic lipids in the vesicle membrane changed the rates and amplitudes of calcein release, the effects not correlating with calculated changes in lipid spontaneous curvature. Mutation of charged residues in the Arg-104, Lys-105, Lys-106 cluster removed high-affinity binding of anionic lipids to MscL, and the presence of anionic lipid no longer affected calcein flux through MscL. Changing the zwitterionic lipid from phosphatidylcholine to phosphatidylethanolamine resulted in a large decrease in the rate of calcein release, the change in rate varying linearly with lipid composition, as expected if spontaneous curvature affected the rate of release. However, rates of release of calcein measured in the presence of phosphatidylethanolamine-N-methyl and phosphatidylethanolamine-N,N-dimethyl did not fit the correlation between rate and curvature established for the phosphatidylcholine/phosphatidylethanolamine mixtures. Rather, the effects of zwitterionic lipid headgroup on calcein flux suggested that what was important was the presence of a proton in the headgroup, able to take part in hydrogen bonding to MscL. We conclude that the function of MscL is likely to be modulated by direct interaction with the surrounding, annular phospholipids that contact the protein in the membrane.

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“…The rationale for this study was that when a non-lamellar lipid, such as PE, which spontaneously forms inverted hexagonal phase, is forced into the planar bilayer structure, this results in a significant stress of lipid packing in the region of the acyl chains (Gruner 1985;Keller et al 1993;Bezrukov et al 1998;Cantor 1999;Bezrukov 2000;Brink-van der Laan et al 2004). Estimates show that the difference in the corresponding lateral pressure between PE and PC membranes can reach hundred atmospheres (Bezrukov 2000;Gullingsrud and Schulten 2004).…”

Section: Vdac Regulation By Mitochondrial Lipidsmentioning

confidence: 99%

VDAC regulation: role of cytosolic proteins and mitochondrial lipids

Rostovtseva

Bezrukov

2008

J Bioenerg Biomembr

203

154

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It was recently asserted that the voltage-dependent anion channel (VDAC) serves as a global regulator, or governor, of mitochondrial function (Lemasters and Holmuhamedov, Biochim Biophys Acta 1762:181-190, 2006). Indeed, VDAC, positioned on the interface between mitochondria and the cytosol (Colombini, Mol Cell Biochem 256:107-115, 2004), is at the control point of mitochondria life and death. This large channel plays the role of a "switch" that defines in which direction mitochondria will go: to normal respiration or to suppression of mitochondria metabolism that leads to apoptosis and cell death. As the most abundant protein in the mitochondrial outer membrane (MOM), VDAC is known to be responsible for ATP/ADP exchange and for the fluxes of other metabolites across MOM. It controls them by switching between the open and "closed" states that are virtually impermeable to ATP and ADP. This control has dual importance: in maintaining normal mitochondria respiration and in triggering apoptosis when cytochrome c and other apoptogenic factors are released from the intermembrane space into the cytosol. Emerging evidence indicates that VDAC closure promotes apoptotic signals without direct involvement of VDAC in the permeability transition pore or hypothetical Bax-containing cytochrome c permeable pores. VDAC gating has been studied extensively for the last 30 years on reconstituted VDAC channels. In this review we focus exclusively on physiologically relevant regulators of VDAC gating such as endogenous cytosolic proteins and mitochondrial lipids. Closure of VDAC induced by such dissimilar cytosolic proteins as pro-apoptotic tBid and dimeric tubulin is compared to show that the involved mechanisms are rather distinct. While tBid mostly modulates VDAC voltage gating, tubulin blocks the channel with the efficiency of blockage controlled by voltage. We also discuss how characteristic mitochondrial lipids, phospatidylethanolamine and cardiolipin, could regulate VDAC gating. Overall, we demonstrate that VDAC gating is not just an observation made under artificial conditions of channel reconstitution but is a major mechanism of MOM permeability control.

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Probability of alamethicin conductance states varies with nonlamellar tendency of bilayer phospholipids

Cited by 256 publications

References 27 publications

Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress

Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress

Importance of Direct Interactions with Lipids for the Function of the Mechanosensitive Channel MscL

VDAC regulation: role of cytosolic proteins and mitochondrial lipids

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