Target recognition, resistance, immunity and genome mining of class II bacteriocins from Gram-positive bacteria

Abstract

Due to their very potent antimicrobial activity against diverse food-spoiling bacteria and pathogens and their favourable biochemical properties, peptide bacteriocins from Gram-positive bacteria have long been considered promising for applications in food preservation or medical treatment. To take advantage of bacteriocins in different applications, it is crucial to have detailed knowledge on the molecular mechanisms by which these peptides recognize and kill target cells, how producer cells protect themselves from their own bacteriocin (self-immunity) and how target cells may develop resistance. In this review we discuss some important recent progress in these areas for the non-lantibiotic (class II) bacteriocins. We also discuss some examples of how the current wealth of genome sequences provides an invaluable source in the search for novel class II bacteriocins.

A Stress-Inducible Quorum-Sensing Peptide Mediates the Formation of Persister Cells with Noninherited Multidrug Tolerance

“…In S. mutans, several class II bacteriocins are expressed through the CSP-ComDE quorum-sensing system (16,26,48). Class II bacteriocins are antimicrobial peptides that function to kill competitors by dissipating the proton motive force via pore formation in the cytoplasmic membrane of target cells (23). Interestingly, preliminary work done in our lab demonstrated that inactivation of mutacin V (CipB), but not mutacin IV (NlmAB), completely abolished the increase in persister numbers observed for the WT strain following pretreatment with the CSP pheromone.…”

Genetic characterisation and heterologous expression of leucocin C, a class IIa bacteriocin from Leuconostoc carnosum 4010

“…The immunity proteins do not prevent the formation of bacteriocin-receptor complex by binding to the receptors competitively. (Kjos et al 2011). As a side effect, glucose transport is also blocked, leading to the reduced growth on glucose.…”

“…In immune cells (b), the bacteriocin mediates the same conformational changes, but the pore is blocked by a specific immunity protein (dark blue) which tightly binds to EII t Man -bacteriocin complex. Adapted from Kjos et al (2011).…”

“…Class IIa bacteriocins permeabilise the target cells by forming pores in the cytoplasmic membrane that subsequently leads to the depletion of the intracellular ATP pool, disturbance of the proton motif force and eventually the cell death Suzuki et al 2005). After contacting the receptor molecule mannose phosphotransferase system (PTS) permease EII t Man on cell membrane, the N-terminal halves of these bacteriocins form a three-stranded anti-parallel β-sheet-like structure which stabilises the binding to the receptor on the target cell membrane (Kjos et al 2011). Simultaneously, the helical C-termini penetrate into the receptor protein (Johnsen et al 2005a).…”

ThefsrQuorum-Sensing System and Cognate Gelatinase Orchestrate the Expression and Processing of Proprotein EF_1097 into the Mature Antimicrobial Peptide Enterocin O16

“…Bacteriocins are found in both Gram-positive and Gram-negative bacteria, and together, they constitute a large and diverse group of antimicrobial peptides and proteins. Within the Gram-positive bacteria, particularly LAB, bacteriocins are found abundantly and have been extensively studied with respect to structure, diversity, mode of action, production, and target specificity (5). Bacteriocins have been divided into three classes: class I, lantibiotics, which are small and heavily modified peptides containing lanthionine residues; class II, unmodified bacteriocins, which are small, unmodified peptides or peptides with minor modifications (such as sulfide bridges); and class III, lytic and relatively large proteins (6).…”