FS_HEPN_TM
Description
PICIs (Phage-inducible chromosomal islands) are highly mobile genetic elements that reside in the bacterial chromosome in the absence of a helper phage. Following infection by the helper phage, PICIs excise and replicate by hijacking the helper phage machinery. The FS_HEPN_TM system was discovered in S. saprophyticus through the manual search for immune systems in flanking regions of SaPIs (S. aureus pathogenicity islands), a type of PICI (N/A) . It is composed of two uncharacterized genes, one with a Cthe_2314 HEPN (higher eukaryotes and prokaryotes nucleotide-binding) domain ref:{doi=10.1186/1745-6150-8-15} and one hypothetical gene containing a single predicted transmembrane domain. The system was tested against 3 phages (one lytic, two temperate) in S. aureus and protected the bacterial host against 2 unrelated phages (Siphoviridae and Herelleviridae) making FS_HEPN_TM a prototypical member of a new anti-phage system.
Molecular Mechanisms
As far as we are aware, the molecular mechanism is unknown.