This family contains lantibiotic ABC transporter permease subunits which are highly hydrophobic, integral membrane proteins, and part of the bacitracin ABC transport system that confers resistance to the Gram-positive bacteria in which this system operates, particularly to type-A lantibiotics. Lantibiotics are small peptides, produced by Gram-positive bacteria, which are ribosomally-synthesized as pre-peptides and act by disrupting membrane integrity. Genes encoding the lantibiotic ABC transporter subunits are highly organized in operons containing all the genes required for maturation, transport, immunity, and synthesis. For example, in Lactococcus lactis, the lantibiotic nisin is active against other Gram-positive bacteria via various modes of actions; however, its self-protection against the pore-forming nisin is mediated by the ABC transporter composed of NisF, NisE and NisG subunits. This family includes the Lactococcus lactis NisG permease subunit that transports nisin to the surface and expels it from the membrane. This family also includes the lantibiotic ABC transporter permease subunits EpiE, MutE, MutG, and SlvE. Self-protection of the epidermin-producing strain Staphylococcus epidermidis Tu3298 against the pore-forming lantibiotic epidermin is mediated by an ABC transporter composed of the EpiF, EpiE, and EpiG proteins. In the mutacin I-producing strain Streptococcus mutans CH43, self-immunity against mutacin I is mediated by proteins MutF, MutE, and MutG, while in salivaricin D-producing strain Streptococcus salivarius 5M6c, mediation is via ABC transporter proteins SlvF, SlvE, and SlvG.
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",