Colicin E3
Colicin E3 is a type of Colicin, a 60kDa[1] bacteriocin made by E. coli which acts against other nearby E. coli to kill them with its 16s rRNase activity; it digests the 16s ribosomal subunit, ultimately leading to the death of the cell.
Synthesis and releaseSynthesis and release
The plasmid containing the colicin E3 gene is called ColE3-CA38, which is structurally homologous to that of the Colicin E2 plasmid[2].
When colicin E3 is synthesised, it binds its 10kDa[3] Colicin Immunity Protein, Im3, to its cytotoxic domain in the cytoplasm. This prevents its RNase activity from occurring in the colicinogenic host, so it does not kill it[4]. It is released as this complex into the surrounding area, and Im3 is only released upon binding to a target cell.
Mechanism of uptakeMechanism of uptake
| |||||||||
| 1ujw, resolution 2.75Å () | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Ligands: | , , , , | ||||||||
| Related: | 1nqe, 1jch | ||||||||
| |||||||||
| |||||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
ColE3 initially binds to the BtuB vitamin B12 receptor. Formation of this complex leads to the unfolding of the N terminal receptor binding coiled-coil domain of ColE3. [5]
The structure shows the complex formed between BtuB and the ColE3 translocation domain [6]
Killing ActivitiesKilling Activities
The C terminal domain of colicin E3 kills the cells that it penetrates by actively degrading the 16s rRNA subunit of the cell's 70S ribosome. This prevents the cell from producing any proteins once attacked, which will lead to the death of the cell. This rRNA cleavage is specific in vivo, but random when the rRNA domain is isolated in vitro[7]. The cleavage is unaffected by the presence of cellular ribonucleases[8]. The specific cleavage observed in vivo occurs within the ribosomal decoding A-site, in between A1493 and G1494, resulting in the complete halt of protein biosynthesis, leading to cell death[9].
ReferencesReferences
- ↑ Chak KF. Expression of the ColE3 operon in maxicells. Proc Natl Sci Counc Repub China B. 1993 Apr;17(2):41-7. PMID:7809274
- ↑ Hiraga S, Sugiyama T, Itoh T. Comparative analysis of the replicon regions of eleven ColE2-related plasmids. J Bacteriol. 1994 Dec;176(23):7233-43. PMID:7525540
- ↑ Chak KF. Expression of the ColE3 operon in maxicells. Proc Natl Sci Counc Repub China B. 1993 Apr;17(2):41-7. PMID:7809274
- ↑ Masaki H, Ohta T. Colicin E3 and its immunity genes. J Mol Biol. 1985 Mar 20;182(2):217-27. PMID:3889348
- ↑ Masi M, Vuong P, Humbard M, Malone K, Misra R. Initial steps of colicin E1 import across the outer membrane of Escherichia coli. J Bacteriol. 2007 Apr;189(7):2667-76. Epub 2007 Feb 2. PMID:17277071 doi:10.1128/JB.01448-06
- ↑ Kurisu G, Zakharov SD, Zhalnina MV, Bano S, Eroukova VY, Rokitskaya TI, Antonenko YN, Wiener MC, Cramer WA. The structure of BtuB with bound colicin E3 R-domain implies a translocon. Nat Struct Biol. 2003 Nov;10(11):948-54. Epub 2003 Oct 5. PMID:14528295 doi:10.1038/nsb997
- ↑ Ohno S, Imahori K. Colicin E3 is an endonuclease. J Biochem. 1978 Dec;84(6):1637-40. PMID:368047
- ↑ Meyhack B, Meyhack I, Apirion D. Colicin E3: a unique endoribonuclease. Proc Natl Acad Sci U S A. 1973 Jan;70(1):156-60. PMID:4567332
- ↑ Zarivach R, Ben-Zeev E, Wu N, Auerbach T, Bashan A, Jakes K, Dickman K, Kosmidis A, Schluenzen F, Yonath A, Eisenstein M, Shoham M. On the interaction of colicin E3 with the ribosome. Biochimie. 2002 May-Jun;84(5-6):447-54. PMID:12423788