Probably the oldest and most widespread antimicrobial strategy in living organisms is the use of antimicrobial peptides. Bacteria secrete such defence peptides, termed bacteriocins, that they use for microbial competitions. Microcins are bacteriocins of less than 10 kDa produced by Escherichia coli and related enterobacteria through the ribosomal pathway. They are synthesized as linear precursors, which can further undergo complex post-translational modifications resulting from dedicated maturation enzymes encoded in the microcin gene clusters, and are processed by proteolytic cleavage. Microcins exert potent bactericidal activities that use subtle and clever mechanisms to cross outer and inner membranes of Gram-negative bacteria. To cross the outer membrane, siderophore-microcins hijack receptors involved in iron acquisition. The lasso-peptide microcin J25, which is characterized by a knotted arrangement where the C-terminal tail is threaded through an N-terminal macrolactam ring, uses a hydroxamate siderophore receptor and the inner-membrane protein SbmA for import in sensitive bacteria, where it inhibits bacterial transcription through binding to RNAP (RNA polymerase). Microcin C produced as a heptapeptide adenylate, requires an outer-membrane porin and an inner-membrane ABC (ATP-binding-cassette) transporter to reach the cytoplasm of target bacteria, where it is processed by proteases into a non-hydrolysable aspartyl-adenylate analogue. Therefore, despite showing different killing mechanisms and the absence of any structural homology, microcins have the common characteristic to use Trojan horse strategies to destroy their competitors. They offer new and promising tracks for further design and engineering of novel efficient antibiotics.
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December 2012
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Conference Article|
November 21 2012
Microcins in action: amazing defence strategies of Enterobacteria
Sylvie Rebuffat
Sylvie Rebuffat
1
1Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Laboratory of Communication Molecules and Adaptation of Micro-organisms, UMR 7245 CNRS-MNHN, CP 54, 57 rue Cuvier, 75005 Paris, France
1emailrebuffat@mnhn.fr
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Publisher: Portland Press Ltd
Received:
August 15 2012
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2012 The Authors Journal
2012
Biochem Soc Trans (2012) 40 (6): 1456–1462.
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Received:
August 15 2012
Citation
Sylvie Rebuffat; Microcins in action: amazing defence strategies of Enterobacteria. Biochem Soc Trans 1 December 2012; 40 (6): 1456–1462. doi: https://doi.org/10.1042/BST20120183
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