Fast and slow kinetics of porin channels from <i>Escherichia coli</i> reconstituted into giant liposomes and studied by patch‐clamp

Berrier, Catherine; Coulombe, Alain; Houssin, Christine; Ghazi, Alexandre

doi:10.1016/0014-5793(92)81011-a

Cited by 57 publications

(52 citation statements)

References 22 publications

(29 reference statements)

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“…The electrophysiological characteristics of these channels, documented by two different techniques, can be summarized as follows: 1) the channels that have large conductances are maximally open at or around 0 mV and close at positive and negative voltages, 2) voltage dependence is asymmetric, 3) the channels exhibit both fast and slow kinetics, and 4) the channels exhibit several subconducting states. The same electrophysiological characteristics can be found in eubacterial porins as documented for OmpF and OmpC (20) and PhoE from Escherichia coli 1 and also in mitochondrial porins (reviewed in Ref. 21).…”

Section: Resultssupporting

confidence: 54%

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Besnard

Martinac

Ghazi

1997

Journal of Biological Chemistry

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Membrane vesicles isolated from the cell envelope of the archaebacterium Haloferax volcanii were either reconstituted in giant liposomes and examined by the patch-clamp technique or were fused into planar lipid bilayers. In addition, cell envelope proteins were solubilized by detergent and reconstituted in azolectin liposomes, which were then fused into planar lipid bilayers. Independently of the technique used the predominant channel activity encountered exhibited the following characteristics. Channels were open at all voltages in the range approximately ؊120 to ؉120 mV and exhibited frequent fast transitions to closed levels of different amplitudes. At voltages greater than 120 mV the channels tended to close in a manner characterized by large, slow transitions of variable amplitudes. The tendency to close at high membrane potentials was much stronger at one polarity. The channel gating pattern was complex exhibiting a range of subconductances of 10 -300 picosiemens in symmetric 100 mM KCl. These electrophysiological characteristics are comparable with those of bacterial and mitochondrial porins, suggesting that the archaeal channels may belong to the general class of porin channels. Some channels showed preference for K ؉ , whereas the others preferred Cl ؊ , suggesting the existence of at least two types of porin-like channels in H. volcanii.

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Section: Resultssupporting

confidence: 54%

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Besnard

Martinac

Ghazi

1997

Journal of Biological Chemistry

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“…Slow kinetics were not observed in these studies performed at low membrane potentials. We subsequently reported the existence of both slow and fast kinetics for OmpC and OmpF channels at higher membrane potentials (Berrier et al, 1992). The discrepancy between these studies and others is not likely due to the technique used (patch-clamp of liposomes for our studies and those of Delcour et al vs. planar lipid bilayers).…”

Section: Discussionmentioning

confidence: 82%

“…This may be ascribed to the fact that porins have not generally been considered as ''ion channels'' in the usual sense of the term, but mostly as static open structures whose complex kinetic behavior has little physiological relevance. In studying the OmpF and OmpC porins of E. coli, we previously showed that these channels are governed by both fast and slow kinetics and we distinguished at least three different closed states of the channels (Berrier et al, 1992). We present here a more exhaustive study of the kinetics of the PhoE porin channels reconstituted in giant liposomes and studied by the patch-clamp technique.…”

Section: Introductionmentioning

confidence: 97%

Electrophysiological Characteristics of the PhoE Porin Channel from Escherichia coli. Implications for the Possible Existence of a Superfamily of Ion Channels

Berrier

Besnard

Ghazi

1997

Journal of Membrane Biology

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Purified PhoE porins from Escherichia coli were reconstituted in giant proteoliposomes obtained by dehydration-rehydration, and studied by the patch-clamp technique. The following electrophysiological characteristics were observed. (i) The channels for which the probability of opening is maximum around 0 mV, closed at positive and negative potentials, at voltages higher than +/-120 mV. (ii) The channels behaved asymmetrically in response to positive and negative potentials. (iii) The channels exhibited two types of kinetics (fast and slow) on very different time scales. (iv) The channels had several closed states including a reversible inactivated state and a large number of substates. Similar characteristics have been described for channels other than bacterial porins, in particular mitochondrial porins and maxi-chloride channels of the plasma membrane of animal cells. These characteristics might constitute the electrophysiological fingerprint of a superfamily of ion channels for which the basic structure, rather than sequence, would have been conserved during evolution.

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“…79 In general the formation of high conductance, voltage gated (two state gating of individual channels with closing at both positive and negative applied potentials) channels exhibiting several sub-conductance states and a complex kinetic behavior is a characteristic feature of ` barrel porins. [80][81][82] Experimental evidence of a close similarity between the ion channel characteristics of beta sheet peptides and that of ` barrel porins revealed for the first time the possibility of self-association of several `-sheet peptide units in presence of membranes into a `-barrel-like structure as in the case of `-barrel pore forming toxins (PFTs).…”

Section: B-sheet Peptide Poresmentioning

confidence: 98%

Amyloid Peptide Pores and the Beta Sheet Conformation

Kagan

Thundimadathil²

2010

Advances in Experimental Medicine and Biology

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O ver 20 clinical syndromes have been described as amyloid diseases. Pathologically, these illnesses are characterized by the deposition in various tissues of amorphous, Congo red staining deposits, referred to as amyloid. Under polarizing light microscopy, these deposits exhibit characteristic green birefringence. X-ray diffraction reveals cross-beta structure of extended amyloid fibrils. Although there is always a major protein in amyloid deposits, the predominant protein differs in each of the clinical syndromes. All the proteins exhibit the characteristic nonnative beta-sheet state. These proteins aggregate spontaneously into extended fibrils and precipitate out of solution. At least a dozen of these peptides have been demonstrated to be capable of channel formation in lipid bilayers and it has been proposed that this represents a pathogenic mechanism. Remarkably, the channels formed by these various peptides exhibit a number of common properties including irreversible, spontaneous insertion into membranes, production of large, heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition of channel formation by Congo red and related dyes and blockade of inserted channels by zinc. In vivo amyloid peptides have been shown to disrupt intracellular calcium regulation, plasma membrane potential, mitochondrial membrane potential and function and long-term potentiation in neurons. Amyloid peptides also cause cytotoxicity. Formation of the beta sheet conformation from native protein structures can be induced by high protein concentrations, metal binding, acidic pH, amino acid mutation and interaction with lipid membranes. Most amyloid peptides interact strongly with membranes and this interaction is enhanced by conditions which favor beta-sheet formation. Formation of pores in these illnesses appears to be a spontaneous process and available evidence suggests several steps are critical. First, destabilization of the native structure and formation of the beta-sheet conformation must occur. This may occur in solution or may be facilitated by contact with lipid membranes. Oligomerization of the amyloid protein is then mediated by the beta strands. Amyloid monomers and extended fibrils appear to have little potential for toxicity whereas there is much evidence implicating amyloid oligomers of intermediate size in the pathogenesis of amyloid disease. Insertion of the oligomer appears to take place spontaneously although there may be a contribution of acidic pH and/or membrane potential. Very little is known about the structure of amyloid pores, but given that the amyloid peptides must acquire beta-sheet conformation to aggregate and polymerize, it has been hypothesized that amyloid pores may in fact be beta-sheet barrels similar to the pores formed by alpha-latrotoxin, Staphylococcal alpha-hemolysin, anthrax toxin and clostridial perfringolysin.

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Fast and slow kinetics of porin channels from Escherichia coli reconstituted into giant liposomes and studied by patch‐clamp

Cited by 57 publications

References 22 publications

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Voltage-dependent Porin-like Ion Channels in the Archaeon Haloferax volcanii

Electrophysiological Characteristics of the PhoE Porin Channel from Escherichia coli. Implications for the Possible Existence of a Superfamily of Ion Channels

Amyloid Peptide Pores and the Beta Sheet Conformation

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