Mode of action of colicin Ib Formation of ion-permeable membrane channels

Weaver, Craig A.; Kagan, Bruce L.; Finkelstein, Alan; Konisky, J

doi:10.1016/0005-2736(81)90521-6

Cited by 43 publications

(19 citation statements)

References 23 publications

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“…On the other hand, no current increase was observed when negative and low positive membrane voltages were applied at pH values _> 5. Very similar effects have been described for a series of channel-forming colicins such as colicin A, B, El, Ia, Ib and K (Schein et al 1978;Weaver et al 1981;Bullock et al 1983;Pattus et al 1983;Nogueira and Varanda 1988). It should be emphasized at this point that such a voltage-dependent induction of channel activity is clearly different from the voltage-dependent gating process of incorporated channels (see below).…”

Section: Discussionmentioning

confidence: 53%

“…Colicins of the El-class include colicin A, B, El, I a, I b and K which permeabilize the cytoplasmic membrane, thereby destroying the membrane potential Offprint requests to: E Pattus (Konisky 1982;Lazdunski et al 1988;. These colicins form well-defined voltage-gated ion channels in artificial membranes (Schein et al 1978;Weaver et al 1981;Cleveland et al 1983;Pressler et al t986;Nogueira and Varanda 1988). Channel-forming colicins have become a valuable tool for the study of the basic principles of membrane channels since they offer some advantages in experimental handling.…”

Section: Introductionmentioning

confidence: 99%

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Colicin N forms voltage- and pH-dependent channels in planar lipid bilayer membranes

1990

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The protein antibiotic colicin N forms ion-permeable channels through planar lipid bilayers. Channels are induced when positive voltages higher than +60 mV are applied. Incorporated channels activate and inactivate in a voltage-dependent fashion. It is shown that colicin N undergoes a transition between an "acidic" and a "basic" channel form which are distinguishable by different voltage dependences. The single-channel conductance is non-ohmic and strongly dependent on pH, indicating that titratable groups control the passage of ions through the channel. The ion selectivity of colicin N channels is influenced by the pH and the lipid composition of the bilayer membrane. In neutral membranes the channel undergoes a transition from slightly cation-selective to slightly anion-selective when the pH is changed from 7 to 5. In lipid membranes bearing a negative surface charge the channel shows a more pronounced cation selectivity which decreases but does not reverse upon lowering the pH from 7 to 5. The high degree of similarity between the channel characteristics of colicin A and N suggests that the channels share common features in their molecular structure.

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Section: Discussionmentioning

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Colicin N forms voltage- and pH-dependent channels in planar lipid bilayer membranes

1990

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“…The exact mode of outer-membrane translocation is still unclear but a recent study suggests that two molecules of CirA are required, one for ColIa/ColIb binding, the second one for its translocation [18], [21]. ColIa/ColIb forms a pore in the inner membrane of sensitive bacteria which leads to disruption of the electrochemical membrane gradient and consequent bacterial death [22]. ColIa/ColIb producers protect themselves by expression of the immunity protein ( imm ) which interferes with ColIa/ColIb action in the inner membrane [23].…”

Section: Introductionmentioning

confidence: 99%

Inflammation Fuels Colicin Ib-Dependent Competition of Salmonella Serovar Typhimurium and E. coli in Enterobacterial Blooms

et al. 2014

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The host's immune system plays a key role in modulating growth of pathogens and the intestinal microbiota in the gut. In particular, inflammatory bowel disorders and pathogen infections induce shifts of the resident commensal microbiota which can result in overgrowth of Enterobacteriaceae (“inflammation-inflicted blooms”). Here, we investigated competition of the human pathogenic Salmonella enterica serovar Typhimurium strain SL1344 (S. Tm) and commensal E. coli in inflammation-inflicted blooms. S. Tm produces colicin Ib (ColIb), which is a narrow-spectrum protein toxin active against related Enterobacteriaceae. Production of ColIb conferred a competitive advantage to S. Tm over sensitive E. coli strains in the inflamed gut. In contrast, an avirulent S. Tm mutant strain defective in triggering gut inflammation did not benefit from ColIb. Expression of ColIb (cib) is regulated by iron limitation and the SOS response. CirA, the cognate outer membrane receptor of ColIb on colicin-sensitive E. coli, is induced upon iron limitation. We demonstrate that growth in inflammation-induced blooms favours expression of both S. Tm ColIb and the receptor CirA, thereby fuelling ColIb dependent competition of S. Tm and commensal E. coli in the gut. In conclusion, this study uncovers a so-far unappreciated role of inflammation-inflicted blooms as an environment favouring ColIb-dependent competition of pathogenic and commensal representatives of the Enterobacteriaceae family.

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“…It has been calculated from the single channel conductance values for colicin El, -3 x l06 ions/channel -sec in 0.1 M salt, that a single colicin molecule can dissipate the cellular membrane potential generated by H + pumping [9]. Colicin A has a similar single channel conductance near neutral pH [51] and the values for colicin Ia and Ib are somewhat larger [31,69]. One can thus view the lethal action of these colicins as occurring through the ability of a single molecule to dissipate the bulk phase membrane potential (A~) and thereby de-energize the state of the membrane when A,tz is the dominant component of the electrochemical potential as defined by Mitchell [45].…”

Section: Introductionmentioning

confidence: 99%

Studies on the mechanism of action of channel-forming colicins using artificial membranes

et al. 1984

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Mode of action of colicin Ib Formation of ion-permeable membrane channels

Cited by 43 publications

References 23 publications

Colicin N forms voltage- and pH-dependent channels in planar lipid bilayer membranes

Colicin N forms voltage- and pH-dependent channels in planar lipid bilayer membranes

Inflammation Fuels Colicin Ib-Dependent Competition of Salmonella Serovar Typhimurium and E. coli in Enterobacterial Blooms

Studies on the mechanism of action of channel-forming colicins using artificial membranes

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