Update gao_ppl.md

Modifying Gao_Ppl #211 (closed)

content/3.defense-systems/gao_ppl.md

@@ -9,11 +9,22 @@ tableColumns:
     Sensor: Unknown
     Activator: Unknown
     Effector: Unknown
+contributors:
+  - Florian Tesson
 relevantAbstracts:
-    - doi: 10.1126/science.aba0372
+  - doi: 10.1126/science.aba0372
 ---
 
 # Gao_Ppl
+
+## Description
+
+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.
+
 ## Example of genomic structure
 
 The Gao_Ppl is composed of 1 protein: PplA.
@@ -78,3 +89,4 @@ end
     style Title4 fill:none,stroke:none,stroke-width:none
 </mermaid>
 
+