Updated mmb_gp29_gp30.md #190

content/3.defense-systems/mmb_gp29_gp30.md

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       doi: 10.1038/nmicrobiol.2016.251
       abstract: |
         Temperate phages are common, and prophages are abundant residents of sequenced bacterial genomes. Mycobacteriophages are viruses that infect mycobacterial hosts including Mycobacterium tuberculosis and Mycobacterium smegmatis, encompass substantial genetic diversity and are commonly temperate. Characterization of ten Cluster N temperate mycobacteriophages revealed at least five distinct prophage-expressed viral defence systems that interfere with the infection of lytic and temperate phages that are either closely related (homotypic defence) or unrelated (heterotypic defence) to the prophage. Target specificity is unpredictable, ranging from a single target phage to one-third of those tested. The defence systems include a single-subunit restriction system, a heterotypic exclusion system and a predicted (p)ppGpp synthetase, which blocks lytic phage growth, promotes bacterial survival and enables efficient lysogeny. The predicted (p)ppGpp synthetase coded by the Phrann prophage defends against phage Tweety infection, but Tweety codes for a tetrapeptide repeat protein, gp54, which acts as a highly effective counter-defence system. Prophage-mediated viral defence offers an efficient mechanism for bacterial success in host-virus dynamics, and counter-defence promotes phage co-evolution.
+contributors:
+    - Hugo Vaysset
+relevantAbstract:
+    - 10.1038/nmicrobiol.2016.251
 ---
 
-# MMB_gp29_gp30
+# MMB gp29-gp30
 
-## To do 
+## Description
+MMB gp29-gp30 is a defense system which was in the MichelleMyBell (MMB) temperate mycobacteriophage. It is an example of prophage-mediated defense :ref{doi=10.1038/nmicrobiol.2016.251}.
+
+## Molecular mechanisms
+To the extent of our knowledge, the precise mechanism of action of MMB gp29-gp30 is not known. The system was shown to protect against lytic infection by temperate phage (e.g. phage Tweety) and does not act through abotive infection. Cells that survive infection tend to become lysogens for the infecting phage. It was also shown that the expression of gp29 alone was toxic in *M. smegmatis* :ref{doi=10.1038/nmicrobiol.2016.251}.
 
 ## Structure
 
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-## Relevant abstract
-::relevant-abstracts
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-items:
-    - doi: 10.1038/nmicrobiol.2016.251
-
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-::