Gao_Ppl or Ppl system is a single gene system. This system was discovered among others in :ref{doi=10.1126/science.aba0372}. This single gene system is described with 2 different domains: PHP (Polymerase and Histidinol Phosphatase) which is a putative nuclease and an ATPase domain.
## Molecular mechanism
As far as we are aware, the molecular mechanism is unknown.