The pore-forming colicin E1 shares the property of all the E colicins in using the vitamin B12 transporter BtuB as its primary receptor in the outer membrane. Mol Gen Genet. ;(1) Cloning of colicin E1 tolerant tolC (mtcB) gene of Escherichia coli K12 and identification of its gene product. Otsuji N, Soejima. The mechanism of export of colicins E1 and E3 was examined. Neither colicin E1 , colicin E3, Nor colicin E3 immunity protein appears to be synthesized as a.

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This arrangement indicates that the transcriptional units for all three genes overlap. The deletion of residues to greatly reduced w1 yield of purified protein relative to the yield of wild-type colicin E1. The resulting plasmid confers immunity to E1 on cells bearing it.

The cytocoxic domain of Colicin E1 is a Pore Formation domain, which forms a channel of colici helices of the protein and phospholipids, in the membrane of the E. Retrieved from ” https: This is in contrast to a model proposed by Zakharov et al. Colicins have a well-defined domain structure, with the killing catalytic or channel-forming domain at the C-terminal coolicin, a receptor-binding R domain in the central part of the molecule, and a translocation T domain encompassing the N-terminal part of the protein Fig.

WikiGenes – pColE1_25 – colicin E1 protein (cea)

The structure of BtuB with bound colicin E3 R-domain implies a translocon. Both E1 and E3 are strongly dependent on TolA 5which is thought to transduce energy from the inner membrane and somehow provide the energy to move the colicin across the outer membrane There is therefore a crucial electrostatic attraction between the positive histadine residue and negative lipids, which when removed at low pH enhances the protein flexibility needed for the channel opening.

As the synthetic T— peptide had no C-terminal histidine tag, unlike all of the tested T domain peptides, the tag was removed from both T— and T57— by thrombin digestion, in order to determine whether the tag sequence was involved in TolC interaction. Antibiotic-sensitive TolC mutants and their suppressors.


To measure killing and protection by T domain in liquid culture, colicin-sensitive E. These results suggest that E1 colocin bind, albeit with relatively low efficiency, to TolC on the outer membrane without first attaching via its R domain to BtuB on the cell surface, and that binding to TolC is sufficient to initiate cplicin of the colicin across the outer membrane.

Colicin E1

Ten-microliter spots cklicin made on lawns of E. But unlike previous results with colicin E1 and TolC and those shown here 172831in vitro binding of the Ia T domain to Cir in planar lipid bilayer membranes could not be demonstrated E. However, it is unique among the E colicins in using TolC, rather than OmpF, as its translocator pathway into the target cell.

Intrinsically disordered protein threads through the bacterial outer-membrane porin OmpF. This weakening of interactions be because a more flexible conformation of the toxin is necessary coilcin membrane insertion – particularly a looser conformation of the membrane-inserted domain induced by neutral or alkaline pH.

This process requires the presence of BtuB, and the OmpT protease, and it is cleaved in the N terminal translocation domain. In addition, the lack of any residues beyond W57 that absorb at nm meant that protein detection during purification was not possible.

When the membrane channel lowers, there is a decrease in channel activity, because of electrostatic interactions strong enough to limit the conformational freedom required to insert the colicin from its surface bound state into the E. Similar binding via T domain alone and subsequent cytotoxicity by colicin Ia have also been demonstrated Open in a separate window. Toolbox Upload file Special pages Printable version Permanent link.

Your Inquiries or Comments. In short, colicin production may only occur in terminally ill cells.

Colicin E1 (microcin) immunity protein (IPR) < InterPro < EMBL-EBI

His is located near to the lipid head groups of the bilayer, and His is in the helix that is translocated to the trans-side of the membrane when the channel is open. A force-activated trip switch triggers rapid dissociation of a colicin from its immunity protein.


Pedigrees of some mutant strains of Escherichia coli K Please review our privacy policy. Mutations of a glycine residue known to face the inside of the TolC channel have been shown to reduce the collcin of killing by colicin E1, implying that passage of the colicin through the channel was obstructed by the bulkier mutant amino acids Two pairs of mutagenic oligonucleotides were used for each pair of histidine-to-leucine mutants Table S1.

TolC is a trimeric protein embedded in the outer membrane of E.

The structural and functional relationships among independently cloned segments of the plasmid ColE1 region that regulates and codes for colicin E1 ceaimmunity imm and the mitomycin C-induced lethality function e have been analysed [ PMID: Until substantial increases in permeability occur, most of the colicin remains cell associated, in the soluble cytosol, rather than in a membrane-associated form.

The open channel changes the rate of increase in the membrane conductance, and this change is maximum at an acidic pH. Store at degrees C. Microbiol Mol Biol Rev Click here to view. Structure and operation of bacterial tripartite pumps. Deletion of either the receptor-binding domain of the colicin or of the bacteria’s BtuB receptor reduces cytotoxicity by three or four orders of magnitude, but it does not totally prevent killing by the colicin.

Further study is required to confirm this.

I thank Alan Finkelstein for many helpful discussions and for critically reading the manuscript. Cilicin colicin operons are generally organized with several major genes. This may simply be a reflection of more efficient translocation of the significantly shorter protein through TolC.

Retaining the colicin plasmid is very important for cells that live with their relatives, because if a cell loses the immunity gene, it quickly becomes subject to destruction by circulating colicin.

The percentage of surviving colonies was calculated from the control culture to which no colicin or T domain was added.