Ion channel forming colicins

Stroud, Robert M.; Reiling, K. Kinkead; Wiener, Michael C.; Freymann, Douglas

doi:10.1016/0959-440x(95)80037-9

Cited by 52 publications

(35 citation statements)

References 27 publications

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“…Consistent with their homology with bacterial toxins, the activity of all these channels is enhanced at low pH. 50 Unlike Bax and Bak, antiapoptotic Bcl-2 family proteins and t-Bid only form large-conductance channels when they are assayed or pre-inserted at low pH (Table 2). 45,48 Importantly, no channel activity has been detected that can be attributed to Bcl-2 in mitochondria of cells overexpressing this protein.…”

Section: Channel-forming Properties Of Bcl-2 Family Proteinsmentioning

confidence: 86%

“…Previously, Antonsson and colleagues 71 identified several derivatives of 2-propanol that blocked cytochrome c release induced by t-Bid in isolated mitochondria; some have IC 50 in the nanomolar range. Recently, two novel agents were found to block the channel activity of recombinant Bax in planar bilayers and inhibit release of cytochrome c induced by t-Bid.…”

Section: Pharmacology Of Mac/bax Channelsmentioning

confidence: 99%

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Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

2006

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Apoptosis is a phenomenon fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Bcl-2 family proteins tightly control this cell death program by regulating the permeabilization of the mitochondrial outer membrane and, hence, the release of cytochrome c and other proapoptotic factors. Mitochondrial apoptosisinduced channel (MAC) is the mitochondrial apoptosisinduced channel and is responsible for cytochrome c release early in apoptosis. MAC activity is detected by patch clamping mitochondria at the time of cytochrome c release. The Bcl-2 family proteins regulate apoptosis by controlling the formation of MAC. Depending on cell type and apoptotic inducer, Bax and/or Bak are structural component(s) of MAC. Overexpression of the antiapoptotic protein Bcl-2 eliminates MAC activity. The focus of this review is a biophysical characterization of MAC activity and its regulation by Bcl-2 family proteins, and ends with some discussion of therapeutic targets.

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Section: Channel-forming Properties Of Bcl-2 Family Proteinsmentioning

confidence: 86%

Section: Pharmacology Of Mac/bax Channelsmentioning

confidence: 99%

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

2006

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“…Following insertion into the inner membrane, the pore-forming colicins, such as colicin E1, A, and N, create a voltage-dependent pore that allows ions to flow out of the cytoplasm, destroying the electrochemical gradients and the protonmotive force (10,11,14). Cellular death results from a loss of K ϩ , as well as a depletion of intracellular ATP and other phosphorylated intermediates (16,30).…”

Section: Discussionmentioning

confidence: 99%

Colicin Concentrations Inhibit Growth of Escherichia coli O157:H7 In Vitro

Callaway

Stahl

Edrington

et al. 2004

Journal of Food Protection

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Escherichia coli O157:H7 is a virulent foodborne pathogen that causes severe human illness and inhabits the intestinal tract of food animals. Colicins are antimicrobial proteins produced by E. coli strains that inhibit or kill other E. coli. In the present study, the efficacy of three pore-forming colicins (E1, N, and A) were quantified in vitro against E. coli O157:H7 strains 86-24 and 933. Colicins E1 and N reduced the growth of E. coli O157:H7 strains, but the efficacy of each colicin varied among strains. Colicin E1 was more effective against both strains of E. coli O157:H7 than colicins A and N and reduced (P < 0.05) populations of E. coliO157:H7 at concentrations <0.1 μg/ml. These potent antimicrobial proteins may potentially provide an effective and environmentally sound preharvest strategy to reduce E. coli O157:H7 in food animals. Disciplines Agriculture | Animal Sciences | Meat Science Comments This article is from Journal of Food Protection 67 (2004): 2603-2607. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. 2603Journal of Food Protection, Vol. 67, No. 11, 2004, Pages 2603-2607 ABSTRACTEscherichia coli O157:H7 is a virulent foodborne pathogen that causes severe human illness and inhabits the intestinal tract of food animals. Colicins are antimicrobial proteins produced by E. coli strains that inhibit or kill other E. coli. In the present study, the efficacy of three pore-forming colicins (E1, N, and A) were quantified in vitro against E. coli O157:H7 strains 86-24 and 933. Colicins E1 and N reduced the growth of E. coli O157:H7 strains, but the efficacy of each colicin varied among strains. Colicin E1 was more effective against both strains of E. coli O157:H7 than colicins A and N and reduced (P Ͻ 0.05) populations of E. coli O157:H7 at concentrations Ͻ0.1 g/ml. These potent antimicrobial proteins may potentially provide an effective and environmentally sound preharvest strategy to reduce E. coli O157:H7 in food animals.

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“…Monomeric and oligomeric forms of these small peptides bind to lipid membranes, forming 19-residue long α-helices lying parallel to the bilayer between polar heads and acyl chains of phospholipids. At high surface densities, δ-toxins associate in bundles of 6-8 antiparallel amphipathic helices which insert into the membrane, forming a hydrophobic channel (Stroud et al, 1998;Dufourcq et al, 1999).…”

Section: Lipids and Pfts (Pore-forming Toxins)mentioning

confidence: 99%

Bacterial protein toxins and lipids: pore formation or toxin entry into cells

Geny

Popoff

2006

Biology of the Cell

120

104

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Lipids are hydrophobic molecules which play critical functions in cells, in particular, they are essential constituents of membranes, whereas bacterial toxins are mainly hydrophilic proteins. All bacterial toxins interact first with their target cells by recognizing a surface receptor, which is either a lipid or a lipid derivative, or another compound but in a lipid environment. Most bacterial toxins are PFTs (pore‐forming toxins) which oligomerize and insert into the lipid bilayer. A common mechanism of action involves the formation of a β‐barrel structure, resulting from the assembly of individual β‐hairpin(s) from individual monomers. An essential step for intracellular active toxins is to translocate their enzymatic part into the cytosol. Some toxins use a translocation mechanism based on pore formation similar to that of PFTs, others undergo a yet unclear ‘chaperone’ process.

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Ion channel forming colicins

Cited by 52 publications

References 27 publications

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

Is MAC the knife that cuts cytochrome c from mitochondria during apoptosis?

Colicin Concentrations Inhibit Growth of Escherichia coli O157:H7 In Vitro

Bacterial protein toxins and lipids: pore formation or toxin entry into cells

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