Colicin

From Proteopedia

Revision as of 20:23, 24 November 2010

Introduction

spinqualitylabelsall models PDB ID 2k5x Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
2k5x, 1 NMR models ()
Gene:	imm, ceiE9 (Escherichia coli), col, cei (Escherichia coli)
Related:	1imq, 1fsj, 1emv
Structural annotation: Resources: InterPro : Ipr000290, Ipr003058, Ipr016128, Ipr003615 Pfam : PF01320
Evolutionary conservation: Toggle Conservation Colors: Rows = identical sequences: Further Information: Caveats, Explanation, Complete Results at ConSurfDB
Resources:	FirstGlance, OCA, PDBsum, RCSB
Coordinates:	save as pdb, mmCIF, xml

Colicins are a type of bacteriocin - peptide and protein antibiotics released by bacteria to kill other bacteria of the same species. Bacteriocins are named after their species of origin; colicins are so-called because they are produced by E. Coli. Because of their narrow killing spectrum which focuses primarily on the species which has made the peptide, bacteriocins are important in microbial biodiversity and the stable co-existence of the bacterial populations.

Colicin peptides are plasmid-encoded. The peptide is released by the cell into the area surrounding it, and then parasitises proteins present in the host cell membrane to translocate across into the host cell. Many protein-protein interactions are involved in the cell entry, and the main system is involved in the grouping of colicins into two families: Group A colicins use the Tol system to enter the host cell, and Group B use the Ton system. Once inside the host cell, the cell killing follows 1st order kinetics - ie one molecule is theoretically sufficient to kill the cell.

The structure of all colicins, of which over 20 have been identified, follows a 3 domain design:
At the N terminus is the Translocation domain (T-)
The Receptor binding domain is at the centre of the peptide (R-)
The C terminus contains the Cytotoxic domain (C-).