RT-nitrilase-Tm (also named UG5-large) is a two genes defense system. It was discovered from P4-like satellites in *E. coli* genomes :ref{doi=10.1016/j.chom.2022.02.01} :ref{doi=10.1093/nar/gkac467}. Its antiphage activity was shown in *E. coli* against phage AL505_P2 (Myoviridae).
The first protein is a reverse transcriptase (RT) fussed with C-N hydrolase domain (nitrilase) ; the second protein is transmembrane protein :ref{doi=10.1093/nar/gkac467}.
The presence of a RT protein allows to draw a parallel between this system and the [DRT defense system](/defense-systems/drt).
## Molecular mechanism
As far as we are aware, the molecular mechanism is unknown.
## Example of genomic structure
## Example of genomic structure
The Rst_RT-nitrilase-Tm is composed of 2 proteins: RT and RT-Tm.
The Rst_RT-nitrilase-Tm is composed of 2 proteins: RT and RT-Tm.