The gop-beta-cll system was shown to have an antiphage activity in 2022 :ref{doi=10.1016/j.chom.2022.02.018} against Escherichia coli phage lambda and P1.
The gop-beta-cll was first described as a nonessential region of the bacteriophage P4 :ref{doi=10.1128/jvi.64.1.24-36.1990}.
This system is composed of 3 genes: gop, beta and cll.
## Molecular mechanism
As far as we are aware, the molecular mechanism is unknown.
The production of the gop protein without beta is toxic :ref{doi=10.1128/jvi.64.1.24-36.1990} suggesting a toxin antitoxin mechanism :ref{doi=10.1016/j.chom.2022.02.018}.
## Example of genomic structure
The Rst_gop_beta_cll is composed of 3 proteins: beta, cll and gop.