1.C.94 The Thuricin S (Thuricin S) Family
Thuricin S, is a class IId bacteriocin produced by Bacillus thuringiensis subsp. entomocidus HD198. According to cell viability tests, thuricin S exerts a bactericidal effect on sensitive Bacillus thuringiensis subsp. darmastadiensis 10T cells. The use of the fluorescent probe 3,3'-dipropylthiadicarbocyanine iodide as an indicator showed that thuricin S interacts with the cytoplasmic membrane to dissipate the transmembrane potential. Thuricin S acts as a pore-forming bacteriocin, since it allows the nonpermeable stain propidium iodide to enter the cells. The loss of membrane integrity and the morphological changes in sensitive cells have been visualized by scanning electron microscopy (Chehimi et al., 2010).
The sactibiotic subclass of bacteriocins contain characteristic cysteine sulphur to α-carbon linkages mediated through post-translational modifications. They include subtilosin (TC# 1.C.84), thuricin CD, thuricin H, and propionicin F (TC# 1.C.94). Thuricin CD is a narrow spectrum anit-Clostridium difficile sactibiotic. Others target Listeria monocytogenes, Gardnerella vaginalis and other pathogens (Mathur et al. 2015).
The reactions catalyzed by thuricins are:
small molecules (in) ⇌ small molecules (out)
Processed pore-forming thuricin S (allows propidium iodide to enter the cell) (Chehimi et al., 2010).
Thuricin S of Bacillus thuringiensis (P84763)
Full-length thuricin S homologue (thuricin17, thuricin H, TucA1, ThnA1) of 58 aas and 1 TMS, or of 40 aas (B5U2V4) and 1 TMS.
Thuricin S homologue of Bacillus thuringiensis (C3FAQ6)
Uncharacterized protein, Thuricin CD or Trnβ, of 49 aas and 1 TMS.
UP of Bacillus cereus
ThuricinCD or Trnα of 47 aas and 1 TMS
Trnα of Bacillus cereus