Abstract
The misuse of antibiotics during the last decades led to the emergence of multidrug resistant pathogenic bacteria. This phenomenon constitutes a major public health issue. Consequently, the discovery of new antibacterials in the short term is crucial. Colicins, due to their antibacterial properties, thus constitute good candidates. These toxin proteins, produced by E. coli to kill enteric relative competitors, exhibit cytotoxicity through ionophoric activity or essential macromolecule degradation. Among the 25 colicin types known to date, colicin M (ColM) is the only one colicin interfering with peptidoglycan biosynthesis. Accordingly, ColM develops its lethal activity in E. coli periplasm by hydrolyzing the last peptidoglycan precursor, lipid II, into two dead-end products, thereby leading to cell lysis. Since the discovery of its unusual mode of action, several ColM orthologs have also been identified based on sequence alignments; all of the characterized ColM-like proteins display the same enzymatic activity of lipid II degradation and narrow antibacterial spectra. This publication aims at being an exhaustive review of the current knowledge on this new family of antibacterial enzymes as well as on their potential use as food preservatives or therapeutic agents.
Highlights
Among Gram-negative bacteria, the Enterobacteriaceae are the major producers of bacteriocins, which are classified in two categories: low molecular weight bacteriocins or microcins, and high molecular weight bacteriocins including colicins produced by Escherichia coli (25 to 80 kDa)
After lipid II translocation towards the periplasmic side of the inner membrane, the GlcNAc-MurNAc-peptide moiety is incorporated into the nascent peptidoglycan macromolecule and the lipid carrier is recycled into a pyrophosphorylated form (C55 -PP). (For comprehensive reviews about peptidoglycan biosynthesis, see [42,43,44,45])
Among bacteriocins interfering with peptidoglycan metabolism, colicin M (ColM) and its orthologs are particular as their mode of action consisting in lipid II cleavage is unique among colicins
Summary
Bacteriocins are ribosomally synthesized antimicrobial proteins or peptides produced by both Gram-positive and Gram-negative bacteria, which are auto-immune to the effects of their own bacteriocin [1,2] They consist of a large and heterologous group of toxins, displaying generally narrow antimicrobial spectra. Among Gram-negative bacteria, the Enterobacteriaceae are the major producers of bacteriocins, which are classified in two categories: low molecular weight bacteriocins or microcins (less than 10 kDa), and high molecular weight bacteriocins including colicins produced by Escherichia coli (25 to 80 kDa) Both microcins and colicins have a narrow spectrum of activity, being active against bacterial strains phylogenetically related to the producer. The central receptor-binding domain is needed for binding a protein at the surface of the target cell, the N-terminal domain is involved in the translocation through the outer membrane, and the C-terminal domain carries the pore-forming or macromolecule degradation activity [9].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
