Multifaceted ABC transporters associated to microcin and bacteriocin export.

Microcins and bacteriocins are ribosomally-synthesized defence peptides produced by Gram-negative and -positive bacteria to target competitors in their niche. Some of them carry posttranslational modifications established by dedicated enzymes. To protect themselves from their own toxic peptides, bacteria use dedicated immunity proteins or expel the toxin using ATP-binding cassette (ABC) transporters. In this last case, this immunity function is associated to export of the antimicrobial peptide out of the producing cells for targeting their competitors. Here we review the characteristics of these ABC-exporters and the mechanisms they use that unexpectedly cover from high promiscuity to high specificity or ensure another function concomitantly. Crown